A case of necrobiotic xanthogranuloma without paraproteinemia presenting as a solitary tumor on the thigh

A 82‐year‐old Korean woman had had a 6‐month history of an asymptomatic, flat, hard, red to brown tumor on her right thigh. This lesion had been slowly enlarging with an advancing margin. She had noted gradually developing pain associated with necrosis and ulceration on the lesion. Examination revealed a solitary, 8 × 7.5 cm, yellow to dark red, telangiectatic tumor with multiple areas of punched out ulceration and a peripheral elevated yellowish margin on the right inner upper thigh ( Fig. 1 ). No clinically similar lesions on the periorbital area or other sites were seen. Histologic examination revealed a massive palisading granulomatous infiltration with several layers of extensive bands of necrobiotic zone in the entire dermis and deep subcutaneous tissue ( Fig. 2a ). In the granulomatous infiltrate in the dermis and subcutis, many various‐shaped, some bizarre, angulated, foreign‐body type multinucleated giant cells, many Touton giant cells, and a few Langhans giant cells were found to be scattered ( Fig. 2b ). There were numerous xanthomatized histiocytes. Dense infiltration of lymphoplasma cells was seen in the periphery of the granuloma and perivascularly. Conspicuous granulomatous panniculitis composed of lymphoplasma cells, polymorphonuclear cells, foam cells, and Touton and foreign‐body giant cells was also seen. However, cholesterol clefts and lymphoid follicles were not seen. Subcutaneous septae were widened by necrobiotic change and fibrosis with thrombosed large vessels. Gram, Gomeri‐methenamine silver and acid‐fast stains were negative. The necrobiotic areas were positive to alcian blue. Laboratory investigation revealed elevated white blood cell counts, anemia and elevated erythrocyte sedimentation rate. The following parameters were within the normal range: lipids, glucose, renal and liver function tests, serum complements, serum immunoglobulins, cryoglobulins and antinuclear antibodies. The findings of chest X‐ray, skull X‐ray and ectorcardiography were normal. Serum electrophoresis and serum immunoelectrophoresis revealed no abnormality. The patient was diagnosed as having necrobiotic xanthogranuloma without paraproteinemia. She was treated with oral steroid (0.5–0.6 mg/kg) and NSAIDS for 1 month with partial improvement of pain and the lesion ceased to enlarge. In the following 1 year of follow‐up, with only intermittent NSAIDS, her lesion did not progress and there were no signs of systemic involvement or new skin lesions. (a) A solitary, red to brown plaque with multiple ulcerations and a peripheral elevated yellowish margin on the inner upper thigh image (a) A dermal and subcutaneous massive xanthogranulomatous infiltrate with zonal necrobiosis of collagen (× 20). (b) Prominent infiltrate of xanthomatized histiocytes and giant cells with perivascular lymphoplasma cells (H&E, × 100) image