Download MBBS Dermatology PPT 19 Mycobacterial Infections Cutaneous Tuberculosis Lecture Notes

Download MBBS (Bachelor of Medicine, Bachelor of Surgery) Dermatology PPT 19 Mycobacterial Infections Cutaneous Tuberculosis Lecture Notes

Mycobacterial Infections:

Cutaneous tuberculosis

Learning objectives

? Classification of cutaneous TB
? Description of various clinical presentations
? Diagnostic principles
? Treatment and other related factors
Epidemiology

? Cutaneous tuberculosis occurs worldwide; incidence

of different forms varying global y

? A form of extrapulmonary TB
? < 1% of al TB cases and about 15% of

extrapulmonary

? Cutaneous tuberculosis- Usual y not a marker of

immunosuppression and, rarely, associated with HIV
infection/AIDS

? In India, scrofuloderma is common in children; lupus

vulgaris commoner in adults

Aetiology

? Term `mycobacterium' in 1896, group of bacteria

producing mouldlike pel icles when grown on liquid

media

? Caused by M. tuberculosis

? Spectrum of cutaneous changes induced by M.

tuberculosis depend upon:

?Route of infection
?Immunological state of the host
?Size of inoculum
?Mere presence of Mycobacteria in the skin does not

lead to the clinical disease
Routes of infection
? Exogenous

? From an external source, through breach in the

skin at the site of trauma

? Endogenous

? Through contiguous involvement of skin

? Through lymphatic spread

? Through haematogenous dissemination

? Auto-inoculation

? Eruptive

Classification

? Inoculation tuberculosis (exogenous source)

? Secondary and haematogenous tuberculosis

(endogenous source)

? Eruptive tuberculosis (tuberculids)
Classification
? Exogenous source

? Tuberculosis chancre (occasional y)

? Warty tuberculosis (Tuberculosis verrucosa cutis)

? Lupus vulgaris (some cases)

Classification
? Secondary tuberculosis (endogenous source)

? Contiguous spread: Scrofuloderma

? Auto-inoculation: Orificial tuberculosis

? Haematogenous tuberculosis

? Acute miliary tuberculosis

? Lupus vulgaris (some)

? Tuberculous gumma


Classification
? Eruptive tuberculosis (tuberculids)

? Micropapular

? Lichen scrofulosorum

? Papular

? Papulonecrotic tuberculid

? Nodular

? Erythema induratum (Bazin)

? Erythema nodosum
Tuberculous chancre

? Occurs fol owing M. tuberculosis inoculation through

breach in the skin of a previously non-infected

individual (a na?ve host)

? Initial y, a smal papule, scab, nodule or a poorly

healing wound

? Gradual y - a painless ulcer with a shal ow, granular

or haemorrhagic base and undermined edges

? Spontaneous healing within 3 to 12 months, with

atrophic scar

Tuberculosis verrucosa cutis

(Warty tuberculosis)

Pathogenesis

? Previously infected individual with moderate to high

immunity

? Accidental superinfection from exogenous sources:

butchers, anatomists (anatomists' wart)

? Common sites

? Adults - fingers and hands

? Children - ankles and buttocks
Tuberculosis verrucosa cutis
?Clinical features
?Smal , solitary, indurated, red or brown, papule or

nodule

?Verrucous plaque (finger-like projections; fissured

surface)

?Regional lymph nodes may enlarge due to secondary

bacterial infection

Tuberculosis verrucosa cutis
Course

? Verrucous lesions persist; but seldom ulcerate

? Usual y chronic course

? Lesions may involute spontaneously, resulting in

sunken, atrophic scars
Lupus vulgaris
Pathogenesis

? Most common form of cutaneous tuberculosis

? Occurs in sensitized individuals with moderate to

high immunity

? Affects al age groups

Lupus vulgaris
Clinical features
?Smal , solitary reddish-brown nodule

?Plaque: Elevated, infiltrated, deep brown in colour

?Slowly expands at one end; heals with scarring at

the other end

?Asymptomatic lesions, commonly affects the

buttocks and trunk
Lupus vulgaris
Clinical presentations

? Plaque

? Ulcerative and mutilating

? Vegetating

? Tumor-like lesions

Lupus vulgaris
Course

? Untreated lesions- Chronic, indolent, over years

? Lesions undergo ulceration and superficial scarring

? Characteristical y thin, white, smooth scars; may

break down or become keloidal

? Complications- contractures, tissue destruction,

development of squamous cel carcinoma in the

scars (8%) ? may take up to 25-30 years; rarely basal

cel carcinoma
Scrofuloderma

(Tuberculosis col iquativa cutis)

Pathogenesis

? Contiguous involvement of the skin overlying a

tuberculous focus, usual y a lymph node, an infected

bone or joint

? Common in children, adolescents and aged; may

affect al age groups

? Sites - Usual y affects the face and neck, often

bilateral y

? Commonly involves the cervical, parotid,

submandibular and supraclavicular lymph nodes;

less commonly, axil ary and inguinal

Scrofuloderma

Clinical features
?Initial y, a firm, subcutaneous nodule, fixed to the

overlying skin

?`Cold' abscess formation [lacks the intense

inflammation]

?Secondary ulceration, sinus tract formation

?Ulcer - undermined edges with granulation
Scrofuloderma
Course

? Numerous sinus tracts and fistulae develop over a

period of several months

? Spontaneous healing may occur, with puckered and

cord-like scars

? Scar tracts - bridge the areas of ulceration or even

normal skin

Orificial tuberculosis
? A rare form of tuberculosis of the mucous

membrane and skin adjoining the orifices

? Presents as a nodule which ulcerates with

undermined edges
Orificial tuberculosis
? Site affected depends on the site of internal

tuberculosis:

? Pulmonary tuberculosis: mouth

? Tuberculosis of pharynx, larynx: lips

? Intestinal tuberculosis: external genitalia; anus;

perianal

? Genitourinary tuberculosis in women: vulva

? Prognosis: poor due to internal disease

Acute miliary tuberculosis of the skin
? Rare fulminating form due to haematogenous

dissemination of Mycobacteria into the skin

? Focus - from a meningeal or pulmonary source

? Crops of numerous, minute, erythematous to bluish,

macules, papules, vesicles, pustules or purpuric

lesions

? Occur on al parts of the body, especial y the trunk

? Usual y occurs in infants, young children, or

fol owing viral infections e.g. measles
Tuberculous gumma (Metastatic tuberculous

abscess)
? Haematogenous dissemination of mycobacteria

from a primary tuberculous focus, during periods of

lowered resistance

? Commonly involves the trunk, extremities or head

? Lesions arise as a single or multiple, firm

subcutaneous nodule or fluctuant abscess

? Ulcers with undermined edges, sinuses and fistulae

may occur

? Healing occurs with cord-like and puckered scarring

Tuberculids (eruptive)

? Occur as a hypersensitivity reaction M. tuberculosis or

its products in a patient with moderate to high

immunity

? Main features:

? A positive tuberculin test

? Evidence of current or past tuberculosis

? A positive response to anti-tuberculous therapy
Tuberculids

Types
Micropapular

? Lichen scrofulosorum
Papular

? Papulonecrotic tuberculid
Nodular

? Erythema induratum (Bazin)

? Erythema nodosum

Erythema induratum of Bazin

(Nodular tuberculid)

? A chronic, recurrent, nodular and ulcerative disorder

? Commonly affects young, or middle-aged, obese

women; men affected occasional y

? Predominantly affects calves; may also occur on upper

limbs, thighs, buttocks and trunk

? The nodules run an indolent course and form ulcers

? Ulcers are ragged, irregular and shal ow, with bluish

edge
Diagnosis of cutaneous TB

? Chronicity of lesions
? Characteristic morphology
? Pathologic feature - caseating granuloma
? Other investigations

Treatment

? Same as TB of other organs
? Rifampin, Isoniazid, Pyrazinamide, Ethambutol x 2 months
? Rifampin, Isoniazid, Ethambutol x 4 months
? Given daily
? Drug resistance in cutaneous ? relatively rare
? Response ? 6 weeks