Interstitial granulomatous dermatitis demonstrating small, discrete skin-colored papules

Abstract

We report the case of a 67-year-old female with a rare variant of interstitial granulomatous dermatitis showing multiple skin-colored papules. Clinically, numerous skin-colored or reddish papules were distributed on her back and posterior thighs with itchy scaly erythema on the upper back. After topical steroid application, skin-colored papules still remained after the disappearance of itchy scaly erythema. Histopathologically, perivascular and interstitial infiltration of lymphocytes and histiocytes with occasional multinucleated giant cells were observed in the superficial and mid reticular dermis, accompanied by mild mucin deposition. Interstitial granulomatous dermatitis is similar to interstitial granuloma annulare, but can be differentiated from it by lesser degrees of collagen degeneration with mucin deposition and frequent association with arthritis or rheumatic diseases. As previously reported, multiple asymptomatic skin-colored papules are considered a rare but distinct variant of interstitial granulomatous dermatitis. Although no apparent underlying disorder has developed in the presented case, careful follow-up needs to be continued.