Cutaneous Tuberculosis

Tuberculosis (TB) is a chronic granulomatous infection caused by species of mycobacteria, most commonly Mycobacterium tuberculosis (Mtb). TB has a worldwide distribution that is heavily weighted toward developing countries and is encountered infrequently in developed parts of the world. Mycobacteria are acid-fast, aerobic bacilli capable of affecting any organ, though the lungs are most commonly involved. Cutaneous tuberculosis (CTB) is a rare form of extrapulmonary TB, accounting for 1.5% to 3% of cases. Mtb is responsible for a majority of CTB cases, Mycobacterium bovis, and bacillus Calmette-Guerin (BCG) are rare causes of the disease.TB is an ancient infectious disease dating back millennia. The first report of CTB is attributed to Rene Laennec, who, in 1826, described a lesion on his hand caused by direct inoculation resulting from the dissections he performed. The causative organism was not identified until 1882, when Robert Koch discovered Mtb. This activity will present clinical categories, epidemiology, pathophysiology, and the approach to diagnosis and treatment of CTB. Classification CTB is polymorphous. Lesion characteristics can appear as nodules, ulcers, infiltrated plaques, abscesses, verrucous papules and nodules, and a combination of the above. The classification of CTB is based on the route and propagation of infection, as well as the host's immune status. Depending on Mtb strain pathogenicity, previous exposure, and host immunity, CTB lesions can be multibacillary or paucibacillary and are categorized as true cutaneous TB or tuberculid. Within each of these categories, varying characteristic forms have been identified, including: True cutaneous TB. Exogenous cutaneous tuberculosis (inoculation TB). Tuberculous chancre [No prior TB exposure]. Tuberculosis verrucosa cutis [Previous TB immunity]. Lupus vulgaris [Previous TB immunity]. Post-BCG vaccination. Subcutaneous abscess. Regional lymphadenopathy. Ulceration. Keloid. Lupus vulgaris. Scrofuloderma. Endogenous cutaneous tuberculosis (originating from a primary site of TB). Contiguity or autoinoculation [Low TB immunity]. Scrofuloderma: arising from contiguous focus (eg, lymph node, bone, joint, epididymis). Tuberculous orificialis: arising from autoinoculation of mucocutaneous tissues (eg, oral, nasal, anogenital) from a primary TB focus. Lupus vulgaris. Hematogenous dissemination (low TB immunity). Lupus vulgaris. Tuberculous gumma (ie, abscess). Acute miliary TB. Tuberculid (hypersensitivity id like reaction to Mtb antigens). Papulonecrotic tuberculid. Lichen scrofulosorum. Erythema induratum of Bazin .