Diffuse plane xanthoma.

Diffuse plane xanthoma is a distinctive and rare dermatologic condition that can signal an underlying, usually hematologic, often malignant condition, including multiple myeloma, monoclonal gammopathy, diffuse histiocytic lymphoma, acute monoblastic leukemia, chronic myelomonocytic leukemia, chronic myeloid leukemia, chronic lymphatic leukemia, adult T-cell lymphoma/leukemia, Sezary syndrome, Waldenstrom's macroglobulinemia, non-Hodgkin's lymphoma, cryoglobulinemia, and Castleman's disease. Diffuse plane xanthoma is clinically characterized by nonpruritic flat, yellowish macules/patches predominantly affecting the face, neck, and upper portion of the body. Histologically, there are lipid-laden macrophages in the dermis that immunohistochemically reveal positive staining for macrophage markers with negative staining for lipid-specific markers. Although there is no specific treatment for diffuse plane xanthoma, treatment of the underlying condition generally reduces or resolves the clinical appearance of the xanthomas.