Erythema nodosum.

This self-limiting disease is characterized by painful, red, cutaneous and subcutaneous nodules, and is often a manifestation of a systemic illness. Sarcoidosis, tuberculosis, coccidioidomycosis, streptococcal infections, inflammatory bowel disease and several drugs can be associated. The lesions, usually on the lower extremities, evolve from raised and tender nodules to a bruised appearance to complete resolution. The prognosis of the skin lesions is excellent, but the clinician's attention must be directed toward the presence of an underlying disease process.