Histopathologic examination revealed a dense dermal infiltrate, predominantly composed of large histiocytes and multinucleated giant cells with a granular eosinophilic cytoplasm, some of which had a ground glass appearance. Neutrophils, lymphocytes, and a few eosinophils were interspersed among the histiocytic cells. Leukophagocytosis and collagenophagocytosis were present in some areas. Immunohistochemically, the mononucleated and multinucleated histiocytes stained positively for KP1 (CD68), but were negative for CD1a and S100 protein.
Asymptomatic Nodule on the Upper Lip—Diagnosis. Arch Dermatol. 2003;139(3):381-386. doi:10.1001/archderm.139.3.381-a