Post traumatic borderline tuberculoid leprosy over knee in an Indian male

Abstract

A 23-year-old Indian male presented with a 6-month history of asymptomatic, skin lesions over the left knee. There was a history of traumatic injury at the same site. While playing football in his village 2 years ago he fell down on the ground and abraded his left knee. Such injuries are routine while playing football, and as it was a minor one no treatment was sought. Cutaneous examination showed multiple shiny, flat-topped, mildly erythematous, discrete and grouped papular lesions and annular plaques with central atrophy, varying in size from 2–8mm in diameter, distributed in a linear fashion on the medial aspect of the left knee, along with an ill-defined, hypopigmented oval patch in the central part on medial aspect of the knee joint (Figure 1). On sensory testing hypoaesthesia to temperature and pinprick sensation was observed in the plaques and on the hypopigmented patch. There were no other skin lesions, nerve thickening or systemic complaints. There was no hepatosplenomegaly or abnormal systemic finding. The haematological investigations, X-ray chest, high resolution CT thorax, serum calcium and serum ACE levels were normal. Mantoux test was 10mm £ 10mm. Staining and culture for fungus was negative. Slit smear examination from the skin lesions and routine sites including both the ear lobes did not reveal any acid-fast bacilli. Histology of skin biopsy revealed multiple non-caseating lymphohistiocytic granulomas in the upper and mid-dermis along with Langhan’s giant cells (Figure 2), at places linear in distribution along the nerves (Figure 3), which suggested borderline tuberculoid leprosy. The Ziehl-Neelsen stain of the tissue did not reveal any acid-fast bacilli. The patient was diagnosed as a case of borderline tuberculoid leprosy and put on WHO PB-MDT (Pauci Bacillary Multidrug Therapy) with tablet dapsone 100mg. daily and capsule rifampicin 600mg. monthly. The lesions regressed significantly after 6 months of treatment, corroborating the diagnosis.