Lymphatic spread in an immunocompetent adult.

Area of Science:

• Dermatology
• Infectious Diseases
• Microbiology

Background:

• Cutaneous tuberculosis (TB) with lymphatic involvement is infrequently documented.
• Tuberculous chancre, a form of TB affecting the skin, is typically associated with direct inoculation.

Observation:

• A 38-year-old immunocompetent woman presented with a four-month-old ulcerated lesion on her left third finger after a prick from a prickly pear.
• Physical examination revealed a linear arrangement of subcutaneous nodules along the arm and an ipsilateral axillary lymph node, indicative of lymphatic spread.
• Histopathology showed granulomatous inflammation, and PCR confirmed Mycobacterium tuberculosis DNA, with no evidence of extracutaneous TB.

Findings:

• The patient was diagnosed with a tuberculous chancre, a rare presentation of cutaneous tuberculosis with lymphatic dissemination.
• Treatment with standard quadruple anti-TB therapy led to significant regression of skin lesions within one month.

Implications:

• This case highlights that tuberculous chancres can occur in immunocompetent adults, not exclusively in immunocompromised individuals or children.
• It underscores the importance of considering cutaneous TB in the differential diagnosis of persistent skin lesions with lymphatic spread, even in the absence of systemic symptoms.
• Early diagnosis and appropriate anti-TB treatment are crucial for managing this rare manifestation of tuberculosis.