A case of lepromatous leprosy misdiagnosed as rheumatoid arthritis

Leprosy, a chronic infection of the skin and peripheral nerves caused by Mycobacterium leprae (ML), is endemic in China, with an incidence rate of 0.29 cases/106 of the population in 2020 [1]. Delayed diagnosis may lead to irreversible disability. Here, we report a case of lepromatous leprosy (LL) misdiagnosed as rheumatoid arthritis (RA).

A 37-year-old Chinese man presented with fatigue, appetite loss and multiple chronic ulcers on his extremities. He had been diagnosed with RA two years previously and unsuccessfully treated with non-steroidal anti-inflammatory drugs. He had continued to experience joint pain and developed joint deformities. Further inquiry revealed that for seven years he had experienced: progressive hair loss from the scalp, eyebrows, and eyelashes; anhidrosis in the hands and feet; and a propensity for burning easily. Physical examination showed erythematous papules, plaques, nodules, burn scars, and ulcers on the extremities (figure 1A, B). His hands were deformed, with shortening of the left fifth finger (figure 1C). He had bilateral non-pitting oedema of the feet and loss of eyebrows and eyelashes. Neurological examination revealed hypoesthesia and anhidrosis in the distal extremities. Blood tests showed increased rheumatoid factor (RF) (142.7 IU/mL), IL-8 (51.67 pg/mL) and IL-10 (10.6 pg/mL) levels. A skin biopsy from the edge of an ulcer contained a dense infiltration with lymphocytes, histiocytes and foamy macrophages of blood vessels and subcutaneous fat lobules …