A 7-year-old child with documented pulmonary tuberculosis develops numerous tiny, skin-coloured to slightly hyperkeratotic follicular papules arranged in crops over the trunk. There is no ulceration and the lesions heal without scarring. Acid-fast staining of the biopsy is negative. Which cutaneous tuberculosis entity fits this description?
- A Lupus vulgaris
- B Tuberculous chancre
- C Lichen scrofulosorum ✓
- D Scrofuloderma
Correct answer: C. Lichen scrofulosorum
Explanation
Lichen scrofulosorum is a tuberculid occurring in children with underlying tuberculosis, typically pulmonary or nodal. It presents as groups of minute lichenoid follicular or perifollicular papules on the trunk, representing a hypersensitivity reaction to mycobacterial antigens rather than viable infection. Bacilli are not demonstrable on staining, the Mantoux test is strongly positive, and lesions heal without scarring once the focus is treated. Lupus vulgaris and scrofuloderma show demonstrable bacilli or granulomatous destruction.
Reference: Rook's Textbook of Dermatology, 9th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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