A UNIQUE NON-LANGERHANS CELL HISTIOCYTOSIS WITH SOME FEATURES OF GENERALIZED ERUPTIVE HISTIOCYTOMA

A symmetric eruption of hundreds of coalescent small red macules and a few slightly elevated papules sparing the flexures was observed in a 73-year-old man. Light microscopic examination showed loose aggregates of small and large histiocytic cells. Electron microscopy showed an a bsence of Langerhans cell granules and lipid droplets. Features shared with generalized eruptive histiocytoma were the symmetry of the erupt ion sparing the flexures, the blue-red coloration, and the absence of lipid-containing foam cells and multinucleated giant cells. However, t he primary occurrence of macules rather than papules or nodules, the t endency of the macules to coalesce, and the dimorphic histiocytoid inf iltrate are not found in generalized eruptive histiocytoma. Neverthele ss, immunohistochemistry confirmed that this unique condition is a for m of MS-1(+) cutaneous non-Langerhans cell histiocytosis.