POEMS syndrome with xanthomatous cells. Polyneuropathy Organomegaly Endocrinopathy M-protein Skin changes

A diffuse xanthomatous infiltration was detected on a biopsy of the hyperpigmented patches in a 40-year-old man with POEMS (Polyneuropathy, Organomegaly, Endocrinopathy, M-protein, Skin changes) syndrome. Multiple biopsies of the hyperpigmented patches showed diffuse or perivascular foamy histiocytes in the upper and mid dermis, a sparse infiltrate of lymphocytes, fibrosis, hyperpigmentation of the basal layer, and capillary proliferation. The foamy cells were positive for periodic acid-Schiff (PAS) with diastase, oil red-O, and CD68. To our knowledge, this is the first case with foamy histiocytes without xanthomatous-appearing skin lesions in POEMS syndrome. It would be worth searching for xanthomatous histiocytes in the hyperpigmented skin of patients with POEMS syndrome.