Lepromatous leprosy presenting with polyarthritis, myositis, and immune-complex glomerulonephritis

A Pakistani man aged 19 years was admitted to a rheumatological unit in the United Kingdom with acute widespread polyarthritis accompanied by night sweats and fever. Preliminary examination suggested Reiter's disease, but further investigation showed acute glomerulonephritis with uraemia. The possibility of periarteritis nodosa, and the prominence of muscle tenderness in the legs, led to biopsies of striated muscle and skin, in both of which were changes typical of lepromatous leprosy, with many Mycobacterium leprae on Ziehl-Neelsen staining. Serum showed IgG-IgM cryoglobulinaemia without antiglobulin activity, and in the recovery phase renal biopsy showed a resolving proliferative glomerulonephritis with linear IgG and IgM immunofluorescence and granular deposits of C3. Clinical signs subsided rapidly under steroid treatment and subsequent progress on anti-leprosy drugs was uneventful. The term erythema nodosum leprosum is inadequate and misleading as a title for a common and important immune-complex reaction of lepromatous leprosy, in which numerous body systems may be involved.