Case 41 Male, 42 years. Papule, skin of backShow diagnosis & comments
Desmoplastic Spitz naevus
Although most desmoplastic Spitz naevi occur on arms and legs of females, exceptions are not uncommon. The histological feratures of this lesion are typical. Desmoplastic melanoma is not a consideration here (compare with cases of desmoplastic melanoma in the slide set of melanoma subtypes): cells and their nuclei are plump rather than long and slender; there is some clustering in upper parts whereas in deeper parts cells are more dispersed; no mitotic activity was identified; the lesion is small and occurs in non-sundamaged skin. The presence of some perivascular round-cell infiltrates is, in view of the other positive and negative findings mendtioned, of no concern.
Kiuru M, Patel RM, Busam KJ. Desmoplastic melanocytic nevi with lymphocytic aggregates. J Cutan Pathol. 2012; 39: 940-4.