Adult Onset of Xanthelasmoid Mastocytosis: Report of a Rare Entity

Xanthelasmoid or pseudoxanthomatous mastocytosis is an extremely rare variant of diffuse cutaneous mastocytosis. Herein, we describe an adult male with cutaneous mastocytosis showing multiple widespread yellowish ovoid papules like eruptive xanthoma. A 60-year-old male visited our outpatient clinic with a 1-year history of generalized yellowish, ovoid, and skin color papular eruption located on the trunk, groin, extremities, with the modest pruritus. Vital signs were stable, and Darier's sign was negative. No other subjective and objective signs were detected during the examination. No abnormality was detected in his diagnostic laboratory tests. Skin biopsy was taken, and histopathologic examination revealed proliferation of mast cells with ovoid and spindle nuclei with distinct cytoplasm borders around the capillaries, which was compatible with mastocytosis. Antihistamine was prescribed for pruritus control which was successful, but eruptions were persistent, and even 1-year phototherapy was not useful.