Warty Tuberculosis

PATHOGENESIS

Tuberculosis verrucosa cutis is a paucibacillary disorder caused by exogenous re-infection (inoculation) in previously sensitized individuals with high immunity.

Inoculation occurs at sites of minor wounds or, rarely, from the patient's own sputum. Members of professional groups handling infectious material are at risk. Children may become infected playing on contaminated ground.

CLINICAL MANIFESTATIONS AND COURSE

Lesions usually occur on the hands or, in children, on the lower extremities as a small asymptomatic papule or papulopustule with a purple inflammatory halo. They become hyperkeratotic and are often mistaken for a common wart. Slow growth and peripheral expansion lead to the development of a verrucous plaque with an irregular border . Fissures discharging pus extend into the underlying brownish red to purplish infiltrated base. The lesion usually is solitary, but multiple lesions may occur. Regional lymph nodes are rarely affected.

Lesions progress slowly and, if untreated, persist for many years. Spontaneous involution eventually occurs, leaving an atrophic scar.

HISTOPATHOLOGY

The most prominent histopathologic features are pseudoepitheliomatous hyperplasia with marked hyperkeratosis, a dense inflammatory infiltrate, and abscesses in the superficial dermis or within the pseudoepitheliomatous rete pegs. Epithelioid cells and giant cells are found in the upper and middle dermis. Typical tubercles are uncommon, and the infiltrate may be non-specific.