SECTION EDITOR: MARY S. STONE, MD; ASSISTANT SECTION EDITORS: SOON BAHRAMI, MD; CARRIE ANN R. CUSACK, MD; SENAIT W. DYSON, MD; MOLLY A. HINSHAW, MD; ARNI K. KRISTJANSSON, MD
Histopathologic evaluation revealed a diffuse infiltration of the dermis by atypical cells with medium-size nuclei and prominent nucleoli, with many cells exhibiting pseudonuclear inclusions and mitoses. Immunoperoxidase staining of the atypical cells was strongly positive for S-100 protein (Figure 3), microphthalmia transcription factor (Figure 4), and NKI/C3, focally weakly positive for Melan-A, and negative for HMB-45. The atypical cells showed no staining for CD3, CD20, cytokeratin 5/6, AE1/AE3, CD1a, and protein gene product 9.5. The lesions were determined to be an unusual pattern of metastatic melanoma in the form of a “leukemiclike” infiltrate of the dermis.
Erythematous Annular Plaques on the Trunk—Diagnosis. Arch Dermatol. 2012;148(4):531–536. doi:10.1001/archderm.148.4.532-b