| Carbuncle | Painful and tender swelling of the skin caused by bacterial infection (commonly Staphylococcus aureus); may be fluctuant and/or discharge pus; there is often surrounding inflammation or cellulitis |
| Infected sebaceous cyst | Common in hair-bearing skin, especially over the face, neck, and trunk; usually slow-growing and painless but will become painful if infected |
| Hematoma | Associated with a history of trauma and most likely to have a sudden onset of swelling after injury; a surrounding area of ecchymosis may be visible |
| Pott's puffy tumor | Frontal scalp swelling caused by frontal osteomyelitis with a bone defect and an epidural collection; symptoms include headache, fever, nasal drainage, and frontal sinus tenderness; if the condition progresses, neurologic complications may develop |
| Inflammatory cutaneous tuberculosis | Low incidence; most often occurs in endemic areas; more common among immunocompromised patients |