A laboratory technician sustains a needle prick while handling tuberculous material on her finger. Three weeks later she develops a painless indurated nodule at the site that breaks down into a clean-based ulcer with regional axillary lymphadenopathy. Mantoux test is initially negative and turns positive over subsequent weeks. What is the diagnosis?

• A Lupus vulgaris from endogenous reactivation
• B Metastatic tuberculous abscess
• C Orificial tuberculosis
• D Tuberculous chancre (primary inoculation tuberculosis) ✓

Explanation

Tuberculous chancre is primary inoculation cutaneous tuberculosis in a person without prior immunity to M. tuberculosis. Two to four weeks after inoculation through broken skin, a painless nodule ulcerates with regional lymphadenopathy, resembling a syphilitic chancre. The initial negative Mantoux that converts later supports primary infection. Orificial tuberculosis arises from autoinoculation in patients with advanced internal tuberculosis and involves mucocutaneous junctions. Metastatic abscesses occur in severely immunosuppressed patients with disseminated disease.

Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.