Interstitial granulomatous dermatitis in a patient with chronic hepatitis C and mixed cryoglobulinemia.

A 55-year-old man presented with a history of asymptomatic, bilateral, figurate dermatosis consisting of erythematous, annular, linear, andarciform, indurated nodules and plaques on the lateral walls of thorax, flanks, and hypogastrium. His medical history was positive for chronic hepatitis C. Skin biopsy was compatible with the diagnosisof interstitial granulomatous dermatitis. Additionalinvestigation revealed positive rheumatoid factor, antinuclear antibodies, and cryoglobulins. Thepatient started treatment with high-potency topical corticosteroid. After 12 weeks of treatment there was a partial clinical improvement of thedermatosis. Interstitial granulomatous dermatitis exhibits a distinct histopathological pattern with a diverse clinical appearance, which can be associated with autoimmune systemic diseases, neoplasms, several drugs, and infections. Optimal therapy for this condition is yet to be established, but topical corticosteroids have been a mainstay of treatment.