Scalloped cell xanthogranuloma.

Abstract

We describe nine cases of scalloped cell xanthogranuloma, a distinct solitary variant of non-Langerhans cell histiocytoses. In this retrospective clinicopathological study scalloped cell xanthogranuloma mostly occurred on the back or head and neck of young adult males diagnosed as a xanthogranuloma, naevus, or basal cell carcinoma. Histology characteristically revealed a sheet-like infiltrate of predominantly scalloped histiocytes (> 79% of all cell types) in the upper dermis. Other mononuclear (vacuolated, xanthomatized, spindle-shaped, oncocytic) and multinucleate (foreign body, ground glass and Touton) histiocytes were also regularly seen. Immunohistochemically, all cases exhibited a macrophage/dendritic cell lineage positive with KP1 (CD68), KiM1p, HAM 56 and factor XIIIa. Ultrastructurally, numerous intracytoplasmic dense, occasionally also myeloid bodies were present. No associated systemic disease, hyperlipidaemia or recurrence were seen during follow-up. These findings are similar to those of early lesions of xanthoma disseminatum: thus, scalloped cell xanthogranuloma could be regarded as a solitary counterpart of xanthoma disseminatum, and, moreover, fits neatly into a unifying concept of non-Langerhans cell histiocytoses.