Cutaneous Tuberculosis

Introduction:

Cutaneous tuberculosis-is the chronic granulomatous disease of skin caused by M.Tuberculosis.It is highly variable in its clinical presentation, depending on the immunologic status of the patient and the route of inoculation of mycobacteria into the skin.M. tuberculosis is anaerobic, non-spore forming, non-motile bacillus with a high cell wall content of high-molecular weight lipids (up to 60% dry weight content).  Cell division occurs from 15-20hours Share the staining characteristic known a acid-fastness: red stain seen upon application of acid-alcohol stain 

Etiology: The obligate human pathogenic mycobacteria: M.tuberculosis, M. bovis, and occasionally, bacillus Calmette-Guérin (BCG)

Mode of Transmission:

In most cases, the organism reaches the skin via lymphatic or hematogenous spread. Inoculation may cause cutaneous tuberculosis.

Some examples of common types of Cutaneous tuberculosis:

1.Lupus vulgaris, 2. Tuberculosis verrucosa cutis, 3.Scrofuloderma,;

4.Erythema induratum [Bazin disease]    ,5. Papulonecrotic tuberculid,

6.Lichen scrofulosorum.

Lupus vulgaris (LV) : lupus vulgaris occurs predominantly on the face

Approximately half of such cases will have evidence of TB elsewhere, so a complete evaluation is mandatory. Because lupus vulgaris is associated with moderately high immunity to TB, most patients will have a positive tuberculin test.Lupus vulgaris typically is a single erythematous plaque composed of grouped red–brown papules, which, when blanched by diascopic pressure, have a pale brownish yellow or “apple-jelly” color.

Tuberculosis Verrucosa Cutis(TVC): Tuberculosis verrucosa cutis occurs predominately on the hands and foot. Clinically the lesion begins hyperkeratotic verrucous papules and plaque resembling as wart. Tuberculin test strongly positive.

Diagnosis of cutaneous tuberculosis

CBC- ESR , Hb

CXR – P/A view

♣MT test (Tuberculin Test) usully positive in most of the cases.

♣Skin Biopsy for histopathological examination

Tubercle /tubercular granuloma/Tuberculoma may be found in the dermis -Central focus of caseation necrosis surrounded by epitheloid cells, occasional langhan’s giant cells, rimmed by lymphocytes, fibroblast .Bacilli may be found in few cases.

Culture

PCR

Treatment

For all forms of cutaneous TB, multi drug chemotherapy is recommended.

Surgical excision is useful for the treatment of isolated lesions of lupus vulgaris and tuberculosis verrucosa cutis, and surgical intervention also may benefit some cases of scrofuloderma.

Medical treatment; Remember notes IREP

INH (5mg/kg/day) + Rifampicin(10mg/kg/day) + Ethambutol(15mg/kg/day +Pyrazinamide(20mg/kg/day)         for 2 months

Followed by INH (5mg/kg/day) + Rifampicin (10mg/kg/day)     for next 4 months

Side effects: All anti-TB drugs are hepatotoxic

INH : Peripheral neuropathy

Rifampicin: orange colour of urine

Ethambutol: Optic neuritis

Pyrazinamide: Precipitating Gout & most hepatotoxic