Leprosy in a rheumatology setting: a challenging mimic to expose.

Leprosy can manifest arthritis both as a complication and a comorbid disorder and can be a challenging differential diagnosis in rheumatology practice due to several common features. Uncommonly, it may present as acute severe polyarthritis with skin lesions and neurological deficit or a digital vasculitis and gangrene. We demonstrate this profile in a retrospective case series analysis of 33 patients (13 females, median age 55 years) in a community-based clinic setting over the period 1998-2012; an electronic search of case records of 41,000 patients was carried out. Rheumatoid arthritis (RA) coexisted in seven patients (three lepromatous, two tuberculoid, and two polyneuritic). Serological rheumatoid factor and antinuclear antibody were often false positive. Several patients of RA were on long-term supervised methotrexate. Rheumatologists should be aware of this clinical mimic to avoid errors in diagnosis and management.