Epidermotropic Xanthoma Mimicking Balloon Cell MelanomaNorthcutt, Alan D. M.D.American Journal of Dermatopathology: April 2000 - Volume 22 - Issue 2 - pp 176-178 Extraordinary Case Reports Abstract Author Information Xanthomas of the skin may mimic balloon cell melanoma because 1) both lesions may exhibit a diffuse dermal proliferation of cytologically similar large vacuolated or clear cells with distinct cytoplasmic membranes, 2) dermal maturation (smaller deep dermal nuclei) is absent in both lesions, 3) melanin pigment is usually absent in balloon cell melanoma, 4) cellular atypia may be minimal in balloon cell melanoma, and 5) mitoses may be absent or rare in balloon cell melanoma. We report a unique xanthoma, which further simulated melanoma by exhibiting epidermotropism and a pseudonesting pattern at the dermal–epidermal junction. The correct diagnosis was made with an immunohistochemical panel revealing tumor cell positivity for CD68 and negativity for S-100 protein and MART-1. Immunohistochemical studies may be required in the critical differential diagnosis of epidermotropic xanthoma and amelanotic balloon cell melanoma. From the Central Texas Pathology Laboratory, P.A., Waco, Texas, U.S.A. Address correspondence to Alan D. Northcutt, M.D., Central Texas Pathology Laboratory, P.A., 3115 Pine Avenue, Suite 108, Waco, TX 76708, U.S.A. © 2000 Lippincott Williams & Wilkins, Inc.