Erythema nodosum. A review.

Erythema nodosum is not an uncommon dermatologic entity. Sarcoidosis and streptococcal infection have become the two most common causes, while tuberculosis was the predominant etiology prior to the use of isoniazid. Histoplasmosis and coccidioidomycosis are two important geographic considerations. Laboratory tests should include a PPD test, chest x-ray, throat culture for beta-streptococcus, and ASO titer determination as a minimum. Symptomatic treatment remains unsatisfactory in many cases, although recent success has been reported with oral potassium iodide.