To differentiate the leprosy agents Mycobacterium leprae and Mycobacterium lepromatosis and correlate them with geographic distribution and clinicopathologic features.
Leprosy is a chronic granulomatous infection caused by Mycobacterium leprae with predominant involvement of skin and nerves. We present a 70-year-old man with leprosy whose initial presentation resembled rheumatologic disease, due to leprae reaction. He presented with an 8-week history of worsening neuropathic pain in the right forearm, associated with necrotic skin lesions on his fingers that had ulcerated. Physical examination revealed two tender necrotic ulcers at the tip of the right middle finger and the dorsal aspect of the left middle finger. The patient had right wrist tenosynovitis and right elbow bursitis. Apart from raised inflammatory markers, the investigations for infection, connective tissue disease, vasculitis, thromboembolic disease and malignancy were negative. During the fourth week of hospitalization, we noticed a 2-cm hypoesthetic indurated plaque on the right inner arm. Further examination revealed thickened bilateral ulnar, radial and popliteal nerves. A slit skin smear was negative. Two skin biopsies and a biopsy of the olecranon bursa revealed granulomatous inflammation. He was diagnosed with paucibacillary leprosy with neuritis. He responded well to multidrug therapy and prednisolone; his symptoms resolved over a few weeks. This case illustrates the challenges in diagnosing a case of leprosy with atypical presentation in a non-endemic country.