An unusual form of localized papulonodular cutaneous histiocytosis in a 6-month-old boy.

Abstract

We report a 6-month-old boy with an unusual form of cutaneous histiocytosis. The lesions were noticed shortly after birth, and there was no evidence of systemic disease. This histiocytic disorder could not be classified according to the Histiocyte Society classification, and was therefore designated an 'unclassified' group II histiocytic disorder. The clinical picture was characterized by dark-red papulonodules with a tendency to coalesce into plaques. Histologically, the infiltrate was characterized by non-epidermotropic histiocytes showing varying degrees of differentiation, eosinophils and lymphocytes, and by the absence of foamy cells and Touton giant cells. As a most conspicuous feature, electron microscopic examination revealed laminated dense bodies, whereas Birbeck granules and comma-shaped bodies were absent. This further distinguished this uncommon variant from the well-known class II histiocytoses. During a 6-month follow-up period all the lesions showed marked regression.