Leprosy, the Great Imitator of Rheumatic Diseases: A Case Study

A 68-year-old Hispanic man was referred to our center for cutaneous vasculitis of the lower extremities, diagnosed via skin biopsy. He had a 10-year history of erythematous plaques complicated by persistent, non-healing ulcers previously treated with prednisone and hydroxychloroquine. Laboratory testing was significant for positive U1-ribonucleoprotein antibody, antinuclear antibody human epithelial-2, and an elevated erythrocyte sedimentation rate. A repeat skin biopsy revealed nonspecific ulcerations. The patient was diagnosed with a mixed connective tissue disease with features of scleroderma. Mycophenolate was initiated, and prednisone was tapered. After two years of relapsing ulcerations on his lower extremities, a third skin punch biopsy showed dermal granulomas with numerous acid-fast organisms, and a polymerase chain reaction identified Mycobacterium lepromatosis, indicating polar lepromatous leprosy with an erythema nodosum leprosum reaction. After three months of minocycline and rifampin therapy, his lower extremity ulcerations and erythema resolved. Our case highlights the variable and elusive nature of this disease, which can mimic many systemic rheumatologic conditions.