Soft Tissue Masses: Evaluation and Treatment

Suraj Achar; Jarrod Yamanaka; Jennifer Oberstar

SURAJ ACHAR, MD, JARROD YAMANAKA, MD, AND JENNIFER OBERSTAR, MD

Am Fam Physician. 2022;105(6):602-612

Author disclosure: No relevant financial relationships.

Soft tissue masses are a common presentation in family physician offices. Although most lesions, including lipomas, fibromas, and epidermal and ganglion cysts, are benign, rare lesions such as soft tissue sarcomas may have serious consequences. Masses that are deep to the fascia, are 5 cm in diameter or larger, grow rapidly, or present suddenly without explanation should prompt further workup. Imaging for concerning lesions may include ultrasonography, radiography, and sometimes magnetic resonance imaging with contrast. Ultrasonography can be used to assess size, depth, solid or cystic nature, and associated vasculature. Magnetic resonance imaging with contrast provides spatial orientation and delineation of soft tissue sarcomas from surrounding tissues such as muscles. Although less commonly used, computed tomography is an alternative in the initial evaluation of concerning masses and can assist with staging of retroperitoneal and visceral sarcomas. Incisional biopsy of a concerning soft tissue mass can also be useful for establishing a diagnosis. Lipomas and epidermal cysts may be excised if they are painful or if there is concern for malignancy. Because of the high mortality rate of soft tissue sarcomas, evaluation of high-risk masses with magnetic resonance imaging with contrast should be expedited with a referral to orthopedic oncology.

Most soft tissue masses in adults are benign.^1,2 Because benign lipomas and epidermal cysts are less common in children, a greater percentage of these masses in children are malignant and account for nearly 20% of solid malignancies in this population.³

Clinical recommendation	Evidence rating	Comments
Signs that increase the risk of malignancy include tumor size of 5 cm or larger, location on or below the fascia, masses matted to surrounding structures, and rapid growth.⁵	C	Case series of patients referred with sarcoma
Point-of-care ultrasonography can be used to diagnosis abscesses.⁷	A	Systematic review and meta-analysis
Consider initial imaging with radiography before more advanced imaging to evaluate for bony involvement and intratumoral calcifications in osteogenic or synoviosarcomas.⁵⁵	C	American College of Radiology guidelines
When a worrisome mass is found, initial radiography followed by an expedited MRI with contrast are recommended pending radiology recommendation and referral to an orthopedic oncologist.^5,19,65	B	Systematic review

Clinical evaluation of soft tissue masses can be challenging because of nonspecific characteristics. The World Health Organization classifies most soft tissue neoplasms according to the tissue of origin. Common neoplasms include angiosarcoma, fibrosarcoma, leiomyosarcoma, liposarcoma, rhabdomyosarcoma, and synoviosarcoma.⁴ Other non-neoplastic masses may include ganglion cysts, hematomas, plantar fibromas, and vascular lesions. Cross-sectional imaging with magnetic resonance imaging (MRI), computed tomography (CT), or ultrasonography may be required to differentiate benign and malignant lesions.⁵ Table 1^1,6–42 and Table 2^{16,23,34,35,43–52} summarize the most common benign and malignant masses, respectively.

Type	History	Examination	Imaging	Treatment
Abscess	Progressive, subcutaneous, erythematous swelling with possible drainage⁶	Erythematous mass	Ultrasonography showing focal collection vs. “cobblestoning” with cellulitis⁷	Incision and drainage with ultrasound guidance⁷ Consider antibiotics if recurrent or patient is immunocompromised^8–10
Epidermal inclusion cyst	Nodule under the skin¹¹	Arise in areas with hair follicles Pain and erythema if inflamed¹¹ Mobile subcutaneous masses Hallmark feature is central punctate^1,12	MRI: well-defined T2 hyperintense lesions, may depend on presence of internal debris; ruptured cysts have a more varied appearance¹²	For mildly inflamed epidermal inclusion cysts, incision and drainage with culture¹² Can consider excision if recurrent¹¹
Ganglion cyst	Arises from joint, ligament, or tendon injuries¹³	Most often on hands, wrists, feet, or ankles^13,14	Ultrasonography to distinguish between cystic and solid masses, locate adjacent blood vessels, and distinguish between other diagnoses, including a ruptured Baker cyst and deep venous thrombosis	Observation if no functional impairment¹⁵ Consider aspiration, steroid injection, or surgical excision if functional impairment or recurrent^14,15
Hemangiomas/arteriovenous malformations	Capillary hemangiomas are the most common type^12,16	Soft, compressible masses; diffuse blue or purple skin discoloration¹⁷	Radiography and ultrasonography may reveal lesions containing phleboliths and mixed echogenicity MRI can demonstrate depth of the lesion¹⁶	Conservative treatment can include observation or intravascular sclerotherapy¹⁷ Surgical referral reserved for patients with symptomatic tumors^17*
Hematoma	Rapid onset Should have an explanation (e.g., anticoagulation, trauma)	Fluctuant mass, sometimes with overlying ecchymosis¹⁸	Ultrasonography and MRI can show extent of the hematoma¹⁹	Mainly conservative treatment; evaluate if persisting or enlarging for more than one month²⁰ Consider embolization if progressively expanding²¹
Intramuscular myxoma	Rare (0.12% of soft tissue tumors) Typically occurs in large skeletal muscles Most common between 40 and 70 years of age; slightly more common in women	Palpable mass, most common on the thigh and lower limb girdle²²	MRI: T1 hypointense to muscle, high signal intensity on T2-weighted or fluid-sensitive sequences	Surgical excision in most cases²²
Lipoma	Most common between 40 and 70 years of age and in patients who are obese^16,23 Slightly more common in men²⁴ Some genetic syndromes cause multiple lipomas	Superficial mass that is freely mobile with a doughy consistency²⁴ Deep masses may involve muscle and move with muscle contraction²⁴	Radiographs may appear normal²⁴ Ultrasonography: often isoechoic to adjacent subcutaneous fat²⁴ MRI is required for any deep mass or subcutaneous lesion ≥ 5 cm²⁴ MRI demonstrates fat signal intensity ²⁴	Monitoring for asymptomatic lipomas Consider excision for symptomatic or painful masses, or for cosmetic reasons²⁴
Lymphangioma: capillary, cavernous, or cystic	Appears at birth or by 2 years of age Pain is uncommon unless infection is present Disfigurement can be significant²⁵	Seen on the neck and axilla Soft on palpation Respiratory compromise is the most serious complication²⁵	Chest radiography may be useful in identifying mediastinal extension or pleural effusions Ultrasonography: hypoechoic, multilocular cystic masses²⁵ CT: cystic lymphangioma; thicker septations are delineated	Observation only in the absence of symptoms Excision is the standard treatment Recurrence can be 27% and mortality about 2%²⁵ Intralesional sclerotherapy is first-line treatment for macrocystic lymphangiomas²⁶
Morton neuroma (peripheral nerve sheath tumor)²⁷	Sensation of a “pebble in the shoe” or burning in toes distal to the neuroma²⁷	No visual clues to neuroma Mulder click test (dorsiflexing the foot and squeezing the metatarsals produces a clicking sound)	Radiography to rule out other sources of foot pain Ultrasonography can be used to identify a neuroma and guide injection MRI: neuroma seen on T1 axial slice²⁸	Wide toe box shoes Cortisone injections Surgical excision
Mucous cyst	Finger swelling, pain, tenderness, decreased range of motion 80% occur between 50 and 70 years of age²⁹ Twice as likely in women than men²⁹ Approximate prevalence: thumb 18%, second finger 26%, third finger 38%, fourth finger 9%, fifth finger 8%²⁹	Nail changes Translucent mass adjacent to the nail bed³⁰	Dermoscopic examination has reduced need for ultrasonography and radiography ³⁰	Surgical excision yielded the highest cure rate (mean of 95%) Second-line: sclerotherapy and cryotherapy Third-line: corticosteroid injections, expression of cyst content³¹
Pilar cyst	90% occur on the scalp³² Most common after 15 years of age Slightly more common in women³²	Swelling over the scalp Area of alopecia Well-defined, oval mass Occurs in areas with dense hair follicles³²	Imaging not usually warranted Ultrasonography: internal echogenic foci with demonstrated calcification, cholesterol crystals, or both; no blood flow in the lesion³³ MRI: homogeneous, isointense signal on T1-weighted images; homogeneous, hyperintense signal on T2-weighted images³² CT: well-defined, hypodense masses with occasional calcification³⁴	If benign, treat with simple local excision If malignant, refer for wide local excision and possible Mohs surgery³²
Plantar fibroma	Mild pain that worsens after walking or standing for longer periods Bilateral in 20% to 50% of cases May have had trauma to the area or family history³⁵	Palpable nodule or focal thickening along the plantar fascia	Ultrasonography: fusiform nodules that are hypoechoic to isoechoic without intrinsic vascularity (comb sign)³⁶ MRI: well-defined mass, isointense to muscle on T1-weighted images; well-defined, broad base at the superficial fascia demonstrates a fascial tail from extension of the tumor along the fascial plane	Can locally recur³⁵ Orthotics Intralesional corticosteroid injection Consider subtotal fasciectomy with wide excision if conservative therapies are ineffective³⁶
Myositis ossificans	Common after trauma³⁷	Painful, rock-like mass Commonly affects quadriceps femoris and brachialis muscles Organized calcification within the muscle³⁸	MRI: classic hyperintense mass, calcifications may appear on T2-weighted images Radiography or CT: early detection with typical peripheral zonal ossification³⁷	Self-limiting with prolonged resolution common Consider referral for debilitating cases
Schwannoma in the foot	Swelling along the flexor surface Most common between 30 and 40 years of age Men and women affected equally³⁹ Account for 5% of benign soft tissue tumors⁴⁰ May present similarly to Morton neuroma	Clinical presentation depends on tumor size and location⁴¹ Motor or sensory disturbances along the flexor surface	Radiograph findings are often negative MRI shows lesions along a neurovascular bundle; a nerve may enter or exit a mass	Small asymptomatic tumors may be followed clinically If symptomatic, patient should be referred for biopsy with histologic examination and surgical excision⁴¹
Tenosynovial giant cell tumor	Swelling most often in hands or feet Common between 30 and 50 years of age Slightly more common in women Second finger is most often affected⁴²	Rounded or lobulated mass appears to encase the surface of a tendon	Radiography: bony erosions Ultrasonography: small tumor with blood flow that does not attach to tendon MRI: lesion has low signal compared with muscle on T1-weighted images; hemosiderin deposition on T2-weighted images⁴¹	Surgical resection Recurrence rate as high as 15%⁴⁰

Type	History	Examination	Imaging	Treatment
Dermatofibrosarcoma protuberans	Median age of presentation is 20 to 59 years Equally common in men and women⁴³ Lesion is slow-growing and present for years Account for 1% of all soft tissue sarcomas	Pink plaque⁴⁴ Approximate prevalence of nodules: trunk 50% to 60%, upper limbs 25%, head and neck 10% to 15%⁴⁴ Untreated lesions may ulcerate or bleed	Ultrasonography shows tentacle-like projections, hypervascularity⁴⁵ MRI or CT is useful for recurrent disease or large and atypical primary lesions⁴⁵	Referral to orthopedic oncology for core needle biopsy and excision Wide excision with negative margins Mohs surgery for lesions that have wide margins or for cosmetic reasons^43,44
Leiomyosarcoma^46,47	Patients may report abdominal or back pain More common in adults older than 55 years In younger age groups, leiomyosarcoma is more common than liposarcoma	Enlarging mass on the limbs but can also occur on the head, neck, and retroperitoneum Palpable abdominal mass or symptoms of bowel obstruction⁴⁶	CT with contrast shows heterogeneous mass MRI can be used for patients with contrast allergies or for further investigation of muscle or bone involvement if equivocal on CT	Referral to orthopedic oncology for core needle biopsy and surgery⁴⁶
Liposarcoma	Accounts for about 17% of all soft tissue sarcomas⁴⁸ Painless, rapidly enlarging soft tissue mass Most common between 50 and 60 years of age Equally common in men and women⁴⁹ Rare in children; in young children, more likely to be lipoblastoma⁵⁰	Fullness or asymmetry, mobile unless attached to bone, nontender Lymph node examination is required	Radiography shows fat-attenuation or soft-tissue masses; calcifications or ossification in 10% to 32% of cases²³ MRI findings can vary significantly depending on subtype and grade^50,51 Large tumor size with thick septa and nodular or patchy nonadipose components are indicative of well-differentiated liposacromas⁵¹	Referral to orthopedic oncology for core needle biopsy and resection
Rhabdomyosarcoma	Painful cervical mass Commonly seen in children younger than 10 years Rare in adults⁵²	Approximate prevalence: head and neck region near orbit 40%, urinary or reproductive organs 30%, extremities 15%, other locations 15%⁴⁷	Ultrasonography is the first-line imaging study for investigating soft tissue masses in children³⁴ Imaging findings vary depending on location	Referral to orthopedic oncology
Synoviosarcoma	Slow growing Most common in adults 30 to 40 years of age^16,47	Mass size typically between 3 cm and 10 cm May be painful	Radiography shows calcification in 33% of cases³⁵ Ultrasonography: heterogeneous mass with areas of necrosis and eccentric calcifications with variable vascularity⁴⁷ MRI: well-demarcated mass, isointense to muscle on T1-weighted images⁴⁷ Extrinsic bone erosion in 11% to 20% of cases	Diagnosis can be delayed because of slow growth Referral to orthopedic oncology for core needle biopsy and resection

History and Physical Examination

Malignant masses may grow over weeks to years depending on the aggressiveness of the tumor.⁵ Both benign and malignant masses can be painless, but those that present suddenly without explanation or are firm, deep, and adhere to surrounding structures are more concerning for malignancy.⁵ Sarcomas do not fluctuate in size, whereas masses such as hemangiomas and ganglion cysts often do.

Based on strong evidence, lesions that are 5 cm in diameter or larger should be evaluated with advanced imaging or the patient referred because of a higher risk of malignancy.^5,52 However, smaller size does not exclude malignancy because approximately 10% of malignant soft tissue masses are smaller than 5 cm when diagnosed.⁵³ Because of the high mortality rate of soft tissue sarcomas and the potential to miss a small sarcoma, any mass that is not definitively diagnosed should be closely monitored or the patient referred to orthopedic oncology.⁵

Examination includes inspection of the skin and palpation of the mass to assess its depth, mobility, and adherence to deeper structures. Measurement can be difficult, but using a 4- to 5-cm golf ball as a reference can be helpful.

Familiarity with the specific features that can differentiate soft tissue masses can be useful for diagnosis and avoiding unnecessary treatment. When the diagnosis is uncertain, family physicians should refer patients to a multidisciplinary treatment center. Table 3 lists coding resources for the use of point-of-care ultrasonography and other skin procedures in the evaluation of soft tissue masses. Figure 1 is an algorithm for the evaluation of soft tissue masses.

Biopsy
https://www.aafp.org/fpm/2019/0300/p15.html

Ganglion cyst aspiration
https://www.aafp.org/afp/2003/0215/p745.html

Point-of-care ultrasonography
https://www.aafp.org/fpm/2020/1100/p33.html

Imaging Studies

ULTRASONOGRAPHY

A detailed ultrasound examination of soft tissue masses often uses a high-resolution (9 to 17 MHz) linear transducer. Ultrasonography can assist in evaluating tumor characteristics such as size, margins, vascularity, cystic nature, and encroachment into surrounding tissues.^2,54 Advantages of using traditional or point-of-care ultrasonography include low cost, no radiation exposure, and the ability to evaluate compressibility and assess real-time blood flow. Point-of-care ultrasonography can be used for follow-up in the clinic to evaluate changes.

RADIOGRAPHY

The accuracy of plain radiography for diagnosing soft tissue tumors is limited. Radiography should be considered before advanced imaging to evaluate for bony involvement and intratumoral calcifications in osteogenic or synoviosarcomas.⁵⁵

MAGNETIC RESONANCE IMAGING

MRI is the most accurate modality for diagnosing soft tissue masses because it can provide further information regarding adjacent anatomic structures, presence of necrosis, border definition, signal intensity, and penetration of fascial planes.^2,35 Although an initial MRI scan can be performed without contrast, noting any concern for malignancy in the description of the imaging order helps the radiologist to select the most appropriate modality.²⁴

COMPUTED TOMOGRAPHY

Although less commonly used, CT can help identify lesion density, bony reactive changes, calcifications, and vascular involvement.⁵⁶ CT is especially helpful when a patient has a medical device that is incompatible with MRI, large body habitus, deep retroperitoneal mass, or a high-risk metallic foreign body.^56,57

Biopsy

If there is a concern for malignancy, biopsy should be performed by the orthopedic oncologist who would manage the potential diagnosis and possible seeding of the biopsy site.^5,24 The location of the biopsy and possible local spread of the malignancy can affect management.⁵ If there is confidence in the diagnosis, benign masses such as epidermal inclusion cysts and lipomas can be removed en bloc by the family physician.^58,59 Tissue from a removed mass should be sent to pathology to confirm the diagnosis. If the diagnosis is in question, imaging should be considered before a procedure.

Laboratory Studies

Although a tissue biopsy may establish a diagnosis, there are no recommended laboratory studies to evaluate a soft tissue mass.⁵⁶

Sarcomas

Soft tissue sarcomas are a broad and heterogenous group of tumors that are most common in adults older than 55 years, although they can occur at any age.⁶⁰ Malignancy in children is rare; however, sarcomas represent up to 15% of childhood malignancies, 60% of which occur in the extremities.⁶¹ Family physicians should be vigilant because patients with sarcomas have a high mortality rate and often do not seek care right away. Nearly one-half of patients diagnosed with sarcomas wait at least one month from recognition of the mass to see a health care professional.⁶¹

Most soft tissue sarcomas begin as a gradually enlarging painless mass without constitutional symptoms such as fever or weight loss. Paresthesia can be present if the mass causes nerve compression. A soft tissue sarcoma should be considered if an apparent hematoma lasts more than one month.^19,20 Although survival has markedly improved, the overall five-year survival rate is only about 60%.^61,62 Signs that suggest malignancy include tumor size of 5 cm (about the size of a golf ball) or larger, location on or below the fascia, matted to surrounding structures, rapid growth, or recurrence of a mass after prior excision^63,64 (Figure 2). When a worrisome mass is found, initial radiography followed by an expedited MRI with contrast are recommended pending radiology recommendation and referral to an orthopedic oncologist.^5,19,65

Common Soft Tissue Masses

ABSCESS

Skin and soft tissue abscesses are common, with increasing incidence.⁶⁶ They can present anywhere on the body but are more often found at sites of skin damage.⁶⁶ Risk factors for progression from cellulitis to abscess include delay in treatment, male sex, smoking, and alcoholism.⁶ Point-of-care ultrasonography is more accurate than clinical examination for diagnosing abscesses and can assess exact size, depth, and presence of loculi within the abscess.⁷ In addition to characterizing an abscess, ultrasonography can guide incision and drainage procedures.⁶⁷

Treatment includes incision and drainage, and concurrent antibiotic therapy can reduce treatment failure.^8,9 Cultures are not recommended for simple, uncomplicated abscesses but can be useful for individuals who are immunocompromised or have recurrent abscesses.¹⁰

LIPOMA

Lipomas are soft, fatty deposits (Figure 3) that account for approximately one-half of benign soft tissue masses.^{1,16,23,50,68–70} Lipomas can develop at any age, with a predilection for the trunk and proximal extremities, although they are most common in patients who are 40 to 70 years of age or obese.^16,23 Presentation in children is often varied and nonspecific, and lesions can grow rapidly during periods of weight gain.⁵⁰ Patients who have family members with multiple lipomas may have a genetic condition called familial multiple lipomatosis, which presents with multiple benign lipomas on the extremities or trunk.²³ Because some lipomas are deep to the fascia, they can be larger than what is felt on palpation.

Common lipoma characteristics visible on ultrasonography include an elongated and well-circumscribed solid mass that may contain a fibrous capsule (Figure 3B). Approximately one-third of benign lipomas may also contain fatty necrosis with calcifications, making a benign lipoma difficult to differentiate from the rare liposarcoma.^69,71

Lipomas are usually benign and can be treated with monitoring. Lipomas that are 5 cm or larger in diameter or have atypical features on MRI, such as septations thicker than 2 mm or nodular soft tissue changes, should be evaluated for surgical excision.³⁵ Excision can be considered for lipomas that are painful or fast growing and for cosmetic reasons. Lipomas have a low rate of recurrence after excision, but possible complications include adhesions, scarring, muscle injury, and permanent nerve damage.^37,58

EPIDERMAL INCLUSION CYST/PILAR CYST

Epidermal inclusion cysts, also called epidermoid cysts and formerly called sebaceous cysts, are dome-shaped masses that arise in areas with hair follicles. These masses contain keratin debris and are encapsulated by a wall of stratified squamous epithelium, with a hallmark central punctum on the skin.^1,12 Epidermal inclusion cysts can present as mobile subcutaneous masses that are as small as a few millimeters to 5 cm in diameter.¹ Multiple epidermal inclusion cysts can be associated with Gardner syndrome.⁵⁹

A rapidly growing epidermal inclusion cyst or recurrence after surgical excision warrants further investigation for malignancy. Epidermal inclusion cysts should be removed en bloc because they can recur if not completely removed. Ruptured cysts may become infected and often require antibiotic treatment.^15,59

The most common scalp cyst, known as a pilar cyst or trichilemmal cyst, arises from the outer root sheath and occurs in areas with dense hair follicles.³² Imaging with ultrasonography or MRI is rarely indicated. Treatment for benign pilar cysts can be simple local excision.

GANGLION CYST

Ganglion cysts (Figure 4) arise from joint, ligament, or tendon injuries. The capsule contains hyaluronic acid and mucopolysaccharides, which are highly viscous.¹⁴ Symptoms can include pain, swelling, and stiffness of the joint.^13,14 Common sites include hands, wrists, feet, and ankles.⁷²

Observation is recommended for mildly symptomatic or asymptomatic cysts that do not cause functional impairment.¹⁴ Aspiration requires a large 18-gauge needle to remove the thick gelatinous fluid, and recurrence is common.⁷² Aspiration should be avoided when neurovascular structures surround the cyst such as with radial-sided volar wrist cysts. Open or arthroscopic excision is suggested if initial conservative therapy is ineffective, and the cyst remains bothersome.¹⁴

BAKER CYST

A Baker cyst is a ganglion cyst of the posterior knee that is located between the semimembranosus and medial gastrocnemius muscles.⁷³ These cysts can be more pronounced during a flare-up of knee arthritis. They may be found incidentally on MRI or ultrasonography. Treatment includes monitoring, aspiration, corticosteroid injection, aspiration with ultrasound-guided fenestration of cyst walls, and arthroscopic cystectomy.⁷³

PLANTAR FIBROMA

Plantar fibromas (Figure 5) are nodular masses arising in the plantar aponeurosis of the foot. They are the second most common type of soft tissue mass in the foot and ankle after ganglion cysts.³⁵ Although the etiology is unclear, past trauma to the foot, Dupuytren contracture, Peyronie disease, and family history increase the risk of plantar fibroma.^35,74

Patients often present with a painful nodular lesion in the midsubstance or superficial aspect of the plantar fascia that is worsened with walking or standing. Plantar fibromas are bilateral in 20% to 50% of cases.³⁵ Examination may reveal a focal thickening along the plantar fascia or a palpable nodule.³⁶ On ultrasonography, plantar fibromas appear as fusiform nodules that are hypoechoic to isoechoic without intrinsic vascularity (comb sign).^5,36

Treatment rarely requires excision, and many plantar fibromas can be managed conservatively with shoe padding or modifications. Corticosteroid injections (under ultrasound guidance if possible) can relieve pain and decrease the size of the fibroma.^36,72 If orthotics and intralesional corticosteroid injections are ineffective, a subtotal fasciectomy with wide excision can be considered.³⁶

Data Sources: Essential Evidence Plus, PubMed, the Cochrane database, and Scopus were searched using the terms soft tissue masses, sarcoma, cyst, ganglion cyst, plantar fibroma, vascular lesions, epidermal cyst, and pilar cyst. Search dates: February 2021 to March 2022.

Wagner JM, Rebik K, Spicer PJ. Ultrasound of soft tissue masses and fluid collections. Radiol Clin North Am. 2019;57(3):657-669.

Gruber L, Gruber H, Luger AK, et al. Diagnostic hierarchy of radiological features in soft tissue tumours and proposition of a simple diagnostic algorithm to estimate malignant potential of an unknown mass. Eur J Radiol. 2017;95:102-110.

Howlader N, Noone AM, Krapcho M, et al. (eds). SEER cancer statistics review, 1975–2018. National Cancer Institute. April 2021. Accessed March 19, 2022. https://seer.cancer.gov/csr/1975_2018/

WHO Classification of Tumours Ed. Board. Soft Tissue And Bone Tumours. 5th ed. Lyon International Agency for Research on Cancer; 2020.

Styring E, Billing V, Hartman L, et al. Simple guidelines for efficient referral of soft-tissue sarcomas. J Bone Joint Surg Am. 2012;94(14):1291-1296.

Picard D, Klein A, Grigioni S, et al. Risk factors for abscess formation in patients with superficial cellulitis (erysipelas) of the leg. Br J Dermatol. 2013;168(4):859-863.

Subramaniam S, Bober J, Chao J, et al. Point-of-care ultrasound for diagnosis of abscess in skin and soft tissue infections. Acad Emerg Med. 2016;23(11):1298-1306.

Gottlieb M, DeMott JM, Hallock M, et al. Systemic antibiotics for the treatment of skin and soft tissue abscesses: a systematic review and meta-analysis. Ann Emerg Med. 2019;73(1):8-16.

Vermandere M, Aertgeerts B, Agoritsas T, et al. Antibiotics after incision and drainage for uncomplicated skin abscesses. BMJ. 2018;360:k243.

Stevens DL, Bisno AL, Chambers HF, et al. Practice guidelines for the diagnosis and management of skin and soft tissue infections: 2014 update by the IDSA. [published correction appears in Clin Infect Dis. 2015;60(9):1448]. Clin Infect Dis. 2014;59(2):147-159.

Meister H, Taliercio M, Shihab N. A retrospective chart review of inflamed epidermal inclusion cysts. J Drugs Dermatol. 2021;20(2):199-202.

Higgins JC, Maher MH, Douglas MS. Diagnosing common benign skin tumors. [published correction in Am Fam Physician. 2016;94(6):419b]. Am Fam Physician. 2015;92(7):601-607.

Meyerson J, Pan YL, Spaeth M, et al. Pediatric ganglion cysts: a retrospective review. Hand (N Y). 2019;14(4):445-448.

Bontempo NA, Weiss APC. Arthroscopic excision of ganglion cysts. Hand Clin. 2014;30(1):71-75.

Head L, Gencarelli JR, Allen M, et al. Wrist ganglion treatment: systematic review and meta-analysis. J Hand Surg Am. 2015;40(3):546-553.e8.

Blacksin MF, Ha DH, Hameed M, et al. Superficial soft-tissue masses of the extremities. Radiographics. 2006;26(5):1289-1304.

Legiehn GM, Heran MKS. Venous malformations: classification, development, diagnosis, and interventional radiologic management. Radiol Clin North Am. 2008;46(3):545-597.

Dohan A, Darnige L, Sapoval M, et al. Spontaneous soft tissue hematomas. Diagn Interv Imaging. 2015;96(7–8):789-796.

Imaizumi S, Morita T, Ogose A, et al. Soft tissue sarcoma mimicking chronic hematoma. J Orthop Sci. 2002;7(1):33-37.

Kontogeorgakos VA, Martinez S, Dodd L, et al. Extremity soft tissue sarcomas presented as hematomas. Arch Orthop Trauma Surg. 2010;130(10):1209-1214.

Touma L, Cohen S, Cassinotto C, et al. Transcatheter arterial embolization of spontaneous soft tissue hematomas: a systematic review. Cardiovasc Intervent Radiol. 2019;42(3):335-343.

Rachidi S, Sood AJ, Rumboldt T, et al. Intramuscular myxoma of the paraspinal muscles. Oncol Lett. 2016;11(1):466-470.

Murphey MD, Carroll JF, Flemming DJ, et al. From the archives of the AFIP: benign musculoskeletal lipomatous lesions. Radiographics. 2004;24(5):1433-1466.

Johnson CN, Ha AS, Chen E, et al. Lipomatous soft-tissue tumors. J Am Acad Orthop Surg. 2018;26(22):779-788.

Sonmez K, Karabulut R, Turkyilmaz Z. Macrocystic lymphangioma in children treated by sclerotherapy with bleomycin. J Craniofac Surg. 2020;31(3):e250-e251.

Giguére CM, Bauman NM, Smith RJH. New treatment options for lymphangioma in infants and children. Ann Otol Rhinol Laryngol. 2002;111(12 pt 1):1066-1075.

Bhatia M, Thomson L. Morton's neuroma – current concepts review. J Clin Orthop Trauma. 2020;11(3):406-409.

Torres-Claramunt R, Ginés A, Pidemunt G, et al. MRI and ultrasonography in Morton's neuroma. Indian J Orthop. 2012;46(3):321-325.

Jabbour S, Kechichian E, Haber R, et al. Management of digital mucous cysts: a systematic review and treatment algorithm. Int J Dermatol. 2017;56(7):701-708.

Chae JB, Ohn J, Mun JH. Dermoscopic features of digital mucous cysts: a study of 23 cases. J Dermatol. 2017;44(11):1309-1312.

Ferreli C, Caravano M, Fumo G, et al. Digital myxoid cysts: 12-year experience from two Italian dermatology units. G Ital Dermatol Venereol. 2018;153(6):847-854.

Satyaprakash AK, Sheehan DJ, Sangüeza OP. Proliferating trichilemmal tumors: a review of the literature. Dermatol Surg. 2007;33(9):1102-1108.

He P, Chen W, Zhang Q, et al. Distinguishing a trichilemmal cyst from a pilomatricoma with ultrasound. J Ultrasound Med. 2020;39(10):1939-1945.

Kawaguchi M, Kato H, Matsuo M. CT and MRI features of scalp lesions. Radiol Med. 2019;124(10):1049-1061.

Hochman MG, Wu JS. MR imaging of common soft tissue masses in the foot and ankle. Magn Reson Imaging Clin N Am. 2017;25(1):159-181.

Young JR, Sternbach S, Willinger M, et al. The etiology, evaluation, and management of plantar fibromatosis. Orthop Res Rev. 2018;11:1-7.

Zhuang KD, Tandon AA, Ho BCS, et al. MRI features of soft-tissue lumps and bumps. Clin Radiol. 2014;69(12):e568-e583.

Mayerson JL, Scharschmidt TJ, Lewis VO, et al. Diagnosis and management of soft-tissue masses. J Am Acad Orthop Surg. 2014;22(11):742-750.

Angelini A, Bevoni R, Biz C, et al. Schwannoma of the foot: report of four cases and literature review. Acta Biomed. 2019;90(1-S):214-220.

Kitagawa Y, Takai S. Optimal treatment for tenosynovial giant cell tumor of the hand. J Nippon Med Sch. 2020;87(4):184-190.

Bancroft LW, Pettis C, Wasyliw C. Imaging of benign soft tissue tumors. Semin Musculoskelet Radiol. 2013;17(2):156-167.

Fotiadis E, Papadopoulos A, Svarnas T, et al. Giant cell tumour of tendon sheath of the digits. a systematic review. Hand (N Y). 2011;6(3):244-249.

Paradisi A, Abeni D, Rusciani A, et al. Dermatofibrosarcoma protuberans: wide local excision vs. Mohs micrographic surgery. Cancer Treat Rev. 2008;34(8):728-736.

Allen A, Ahn C, Sangüeza OP. Dermatofibrosarcoma protuberans. Dermatol Clin. 2019;37(4):483-488.

Zou MH, Huang Q, Yang T, et al. Role of ultrasound in the diagnosis of primary and recurrent dermatofibrosarcoma protuberans. BMC Cancer. 2021;21(1):909.

Mestiri S, Elghali MA, Bourigua R, et al. Soft tissue leiomyosarcoma— diagnostics, management, and prognosis. Rare Tumors. 2019;11 :2036361318820171.

Renn A, Adejolu M, Messiou C, et al. Overview of malignant soft-tissue sarcomas of the limbs. Clin Radiol. 2021;76(12):940.e1-940.e16.

Henze J, Bauer S. Liposarcomas. Hematol Oncol Clin North Am. 2013;27(5):939-955.

Gupta P, Potti TA, Wuertzer SD, et al. Spectrum of fat-containing soft-tissue masses at MR imaging. Radiographics. 2016;36(3):753-766.

Sheybani EF, Eutsler EP, Navarro OM. Fat-containing soft-tissue masses in children. Pediatr Radiol. 2016;46(13):1760-1773.

Ohguri T, Aoki T, Hisaoka M, et al. Differential diagnosis of benign peripheral lipoma from well-differentiated liposarcoma on MR imaging. AJR Am J Roentgenol. 2003;180(6):1689-1694.

Jawad N, McHugh K. The clinical and radiologic features of paediatric rhabdomyosarcoma. Pediatr Radiol. 2019;49(11):1516-1523.

Datir A, James SLJ, Ali K, et al. MRI of soft-tissue masses: the relationship between lesion size, depth, and diagnosis. Clin Radiol. 2008;63(4):373-378.

Hung EHY, Griffith JF, Yip SWY, et al. Accuracy of ultrasound in the characterization of superficial soft tissue tumors: a prospective study. Skeletal Radiol. 2020;49(6):883-892.

Kransdorf MJ, Murphey MD, Wessell DE, et al.; Expert Panel on Musculoskeletal Imaging. ACR appropriateness criteria soft-tissue masses. J Am Coll Radiol. 2018;15(5S):S189-S197.

Mayerson JL, Scharschmidt TJ, Lewis VO, et al. Diagnosis and management of soft-tissue masses. Instr Course Lect. 2015;64:95-103.

Panicek DM, Gatsonis C, Rosenthal DI, et al. CT and MR imaging in the local staging of primary malignant musculoskeletal neoplasms: report of the Radiology Diagnostic Oncology Group. Radiology. 1997;202(1):237-246.

Salam GA. Lipoma excision. Am Fam Physician. 2002;65(5):901-904.

Zuber TJ. Minimal excision technique for epidermoid (sebaceous) cysts. Am Fam Physician. 2002;65(7):1409-1412.

Nystrom LM, Reimer NB, Reith JD, et al. Multidisciplinary management of soft tissue sarcoma. ScientificWorldJournal. 2013:852462.

Weaver R, O'Connor M, Carey Smith R, et al. The complexity of diagnosing sarcoma in a timely manner. BMC Health Serv Res. 2020;20(1):711.

Jacobs AJ, Michels R, Stein J, et al. Improvement in overall survival from extremity soft tissue sarcoma over twenty years. Sarcoma. 2015:279601.

Buvarp Dyrop H, Vedsted P, Rædkjær M, et al. Routes to diagnosis for suspected sarcoma: the impact of symptoms and clinical findings on the diagnostic process. Sarcoma. 2016:8639272.

Sinha S, Peach AHS. Diagnosis and management of soft tissue sarcoma. BMJ. 2010;341:c7170.

Miller BJ. Use of imaging prior to referral to a musculoskeletal oncologist. J Am Acad Orthop Surg. 2019;27(22):e1001-e1008.

Taira BR, Singer AJ, Thode HC, et al. National epidemiology of cutaneous abscesses: 1996 to 2005. Am J Emerg Med. 2009;27(3):289-292.

Russell FM, Rutz M, Rood LK, et al. Abscess size and depth on ultrasound and association with treatment failure without drainage. West J Emerg Med. 2020;21(2):336-342.

Zhang J, Li Y, Zhao Y, et al. CT and MRI of superficial solid tumors. Quant Imaging Med Surg. 2018;8(2):232-251.

Lisson CS, Lisson CG, Beer M. Radiological diagnosis of soft tissue tumors in adults. Rofo. 2019;191(4):323-332.

Myhre-Jensen O. A consecutive 7-year series of 1331 benign soft tissue tumours. Acta Orthop Scand. 1981;52(3):287-293.

Chan LP, Gee R, Keogh C, et al. Imaging features of fat necrosis. AJR Am J Roentgenol. 2003;181(4):955-959.

Kennedy JG, Ross KA, Smyth NA, et al. Primary tumors of the foot and ankle. Foot Ankle Spec. 2016;9(1):58-68.

Van Nest DS, Tjoumakaris FP, Smith BJ, et al. Popliteal cysts: a systematic review of nonoperative and operative treatment. JBJS Rev. 2020;8(3):e0139.

Carroll P, Henshaw RM, Garwood C, et al. Plantar fibromatosis: pathophysiology, surgical and nonsurgical therapies: an evidence-based review. Foot Ankle Spec. 2018;11(2):168-176.