A laboratory technician sustains a needle prick while handling material from a known pulmonary tuberculosis patient. Three weeks later she develops a painless, indurated nodule at the puncture site that later ulcerates, along with regional axillary lymphadenopathy. She is otherwise well and the Mantoux test converts to positive. This presentation represents:

• A Tuberculous chancre (primary inoculation tuberculosis) ✓
• B Scrofuloderma
• C Tuberculosis verrucosa cutis
• D Metastatic tuberculous gumma

Explanation

Tuberculous chancre results from direct inoculation of M. tuberculosis into the skin of a person without prior sensitisation, producing an indurated nodule that ulcerates with painless regional lymphadenopathy after about 2 to 4 weeks, mimicking syphilitic chance. Verruca necrogenica differs because it occurs in previously sensitised individuals and forms warty plaques rather than an ulcerating nodule. Scrofuloderma arises from contiguous spread of an underlying focus.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.