Microscopic examination revealed a dermal, amelanotic spindle cell proliferation arranged in whorls, infiltrating the entire reticular dermis. The fascicles had no contact with the overlying epidermis. Higher magnification showed nuclear pleomorphism, hyperchromatism, scattered mitoses, and marked stromal desmoplasia with a focal lymphoid inflammatory infiltrate. The depth of invasion of the tumor was Clark level IV, while the Breslow thickness was 3 mm. Immunohistochemical stains were positive for S100 protein, HMB-45, and vimentin. Stains for other markers, such as actin, cytokeratin, desmin, and epithelial membrane antigen, were all negative.
Dome-Shaped Lesion on the Nose—Diagnosis. Arch Dermatol. 2003;139(9):1209-1214. doi:10.1001/archderm.139.9.1209-a