Papular xanthoma: a clinicopathological study of 10 cases

Papular xanthoma (PX) is one of several clinicopathologic variants of normolipemic cutaneous non-Langerhans cell histiocytoses (n-LCH). PX represents a monomorphous reaction pattern of n-LCH characterized by the presence of predominantly xanthomatized macrophages.

The purpose of this study was to identify the clinical, histological and immunohistochemical characteristics of PX.

A series of 10 cases of PX was identified and the results compared with the other histologic subtypes, namely the polymorphous and the remaining other monomorphous reaction patterns in n-LCH.

In this clinicopathologic study, papular xanthoma presented clinically mainly as solitary papule, with a male to female ratio of4 : 1, in an age range from 13 to 57 years and a biphasic occurrence: in the young adolescence and middle ages. It was predominantly located on the trunk, the extremities, and rarely on the head. Clinically, PX was described as xanthoma, 'cutaneous tumor', but also as atheroma, keloid, histiocytoma, Spitz's nevus or clear cell acanthoma. Histology showed moderately well circumscribed exoendophytic papules with a regular epidermis and a dense infiltration of xanthomatized macrophages interspersed by numerous Touton type giant cells. Immunohistochemically mono- and multinucleated macrophages were consistently positive with KiM1p; while only giant cells were labeled with KP1 (CD68), the reactivity with HAM 56 was much more variable. Up to 50% of the xanthomatized cells labeled positive for the lectin peanut agglutinin. In one case the xanthomatized cells stained positive for CD34. Staining for factor XIIIa and CD1a were negative.

This series confirms PX as a rare, but distinguished clinicopathologic entity in the spectrum of n-LCH of the skin.