The biopsy specimen showed a dense, diffuse infiltrate of large cells located in the entire dermis and subcutis, sparing the epidermis. The infiltrating neoplastic cells had a polyhedral shape, central pale nuclei, and abundant clear cytoplasm. Periodic acid–Schiff–positive granules were detected within the cytoplasm of the cells before but not after digestion with diastase, and immunohistochemical staining was positive for AE1/AE3 cytokeratins. These findings were consistent with the diagnosis of cutaneous metastasis, although the patient did not have a history of cancer.
A 2-Year History of an Asymptomatic Scalp Nodule—Diagnosis. Arch Dermatol. 2003;139(11):1497-1502. doi:10.1001/archderm.139.11.1497-a