An 8-year-old boy presents with well defined annular lesion over the buttock with central scarring that is gradually progressive over the last 8 months. The diagnosis is

B i.e. Lupus vulgarisAnnular plaque with central scarring - Typically seen in Lupus vulgaris.Most common sites in India = Buttocks and face.Cause:The underlying focus of TB (bone, joint or lymph node).Contiguous extension of disease from underlying affected tissue.By hematogenous or lymphatic spread.Arise after exogenous inoculation.A complication of BCG vaccination.Features & manifestations:Cutaneous TB more commonly affects buttocks & extremities rather than the face.Such a pattern is usually due to reinoculation and may relate to playing without clothing or shoes.Lesions:Becomes flat plaques with a serpiginous or polycyclic outline & a smooth surface or psoriasiform scaling: there may be erosions, ulceration, and scarring.Hyperophic forms appear as a soft mass with a nodular, hyperkeratotic surface.