An unvaccinated toddler develops a firm, painless, punched-out ulcer on the cheek two weeks after a household contact with open pulmonary tuberculosis kissed the site. The regional cervical nodes are enlarged. Ziehl-Neelsen stain of the ulcer edge shows numerous acid-fast bacilli. The most likely diagnosis is:

• A Scrofuloderma
• B Tuberculosis chancre ✓
• C Lupus vulgaris
• D Orificial tuberculosis

Explanation

Tuberculosis chancre is primary inoculation cutaneous tuberculosis in a person without prior immunity, typically a child inoculated by direct contact with infected sputum. It presents as a painless ulcer with regional lymphadenopathy after 2 to 4 weeks, and unlike other forms of cutaneous TB it shows abundant bacilli on smear because immunity has not yet developed. Scrofuloderma spreads from an underlying infected node, lupus vulgaris arises in previously sensitised skin with few bacilli, and orificial TB involves mucosal surfaces.

Reference: Rook's Textbook of Dermatology, 9th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.