Synonym: primary cutaneous tuberculous complex
Clinical features:
(1) The lesion occurs in a person previously unexposed to tuberculosis, so the tuberculin skin test may be negative or show recent conversion.
(2) The lesion develops at a site of direct inoculation of Mycobacterium tuberculosis into the skin.
(3) There is a subsequent formation of a skin nodule that often ulcerates, forming a chancre.
(4) Lymphangitis with proximal lymphadenopathy may develop.
where:
• The presence of a primary lesion and distended lymphatics draining to one or more enlarged lymph nodes is similar to a Ghon's complex in pulmonary tuberculosis.
A biopsy of the skin or lymph node will show granulomatous inflammation, often with numerous acid fast bacilli (AFB).
A culture of the lesion or molecular marker is needed to confirm the presence of Mycobacterium tuberculosis. Other mycobacteria can cause similar lesions.
Complications:
(1) caseation within the lymph node, with draining of the lymph node to the skin, resulting in scrofuloderma
