Histological sections of both biopsy specimens showed a lichenoid infiltrate of mononuclear cells with abundant eosinophilic cytoplasm and reniform vesicular nuclei within the papillary dermis. Some of the neoplastic cells had a longitudinal groove, giving them a "coffee bean" appearance. Occasional multinucleate cells were seen, in addition to scattered eosinophils and numerous lymphocytes. Epidermotropism was focally present. The overlying epidermis was focally eroded within the scalp biopsy specimen and extensively ulcerated within the labial biopsy specimen. The mononuclear neoplastic cells were confirmed to be Langerhans cells by exhibiting strong immunohistochemical staining for S100 protein and CD1a.
Papular Eruption of the Scalp Accompanied by Axillary and Vulvar Ulcerations. Arch Dermatol. 2001;137(9):1241-1246. doi: