Leprous osteitis presenting as bone cyst and erosions.

A 30-year-old man presented to the Hansen outpatient department with swelling and ulceration of toes for 2 months and swelling of the right fifth and fourth fingers and the left second finger for 1 month. In addition to skin lesions of lepromatous leprosy (subpolar type), there was nontender, non-fluctuant swelling of the right fifth and fourth fingers and left second finger. Skin over the right fifth finger showed sinus-like openings with associated purulent discharge. He also had swelling and ulceration of second left toe. Slit-skin smear (SSS) showed a bacterial index of 6+ from the ear lobes and cutaneous nodules, 4+ from the patch, and 3+ from normal skin. Modified Ziehl-Neelsen staining of the discharge extruding from the sinuses on the right fifth finger also showed abundant acid-fast bacilli. Radiography of the hands and feet showed lytic lesions in the distal epimetaphyseal region o proximal phalanx of the right fifth finger and left second finger and erosion of distal end of proximal phalanges of both second toes. Histopathological examination of biopsy specimen from the patch (back) showed features of lepromatous leprosy, and Fite-Faraco stain for tissue acid-fast bacteria (AFB) was strongly positive. Fine-needle-aspiration cytology (FNAC) from the lytic lesion in the bone also showed predominantly foamy macrophages with strongly positive staining for AFB with a few interspersed lymphocytes, epithelioid cells and Langhans giant cells. On the basis of these features, a clinical diagnosis of subpolar lepromatous leprosy with leprous osteitis was made. In today's clinical era of improved case detection and prompt treatment with effective multidrug regimens, advanced bone changes are rarely encountered. We describe this case of lepromatous leprosy that developed cavitating lesions of the phalanges of the hand, seen on x-ray as well-defined bone cyst and erosions.