Tuberculosis & Leprosy
Tuberculosis
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Mycobacterium tuberculosis is most common
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Mycobacterium bovis,rare, spread to humans by
milk
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Dormant tuberculosis of the skin can also be
reactivated by systemic corticosteroids,
immunosuppressants and new anti-TNF
biological agents.
Inoculation tuberculosis
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Inoculation into skin causes a wart-like lesion at
the site
lupus vulgaris
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Systemic spread to the skin (lupus vulgaris) from an
underlying infected lymph node, or from a
pulmonary lesion.
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reddish-brown scaly plaque slowly enlarges, and can
damage deeper tissues such as cartilage, leading to
ugly mutilation which may cause scarring and
contractures.
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Lesions occur most often around the head and neck.
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Diascopy shows up the characteristic brownish
‘apple jelly’ nodules.
The clinical diagnosis should be confirmed by biopsy.
Scrofuloderma
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mixture of lesions (irregular puckered scars, fistulae
and abscesses) of skin overlying a tuberculous
lymph node or joint , most commonly seen in the
neck.
Tuberculides
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Papulonecrotic tuberculides – By finding
mycobacterial DNA by polymerase chain reaction
(PCR)- are recurring crops of firm dusky papules,
which may ulcerate, favouring the points of the
knees and elbows.
Erythema induratum (Bazin’s disease)
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deep purplish ulcerating nodules occur on the backs of the lower legs,
usually in women with a poor ‘chilblain’ type of circulation.
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Erythema nodosum may also be the result of tuberculosis elsewhere.
Investigations
Biopsy for:
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microscopy (tuberculoid granulomas)
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bacteriological culture
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detection of mycobacterial DNA by PCR
Mantoux test
Chest X-ray
Treatment
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The treatment of all types of cutaneous
tuberculosis should be with a full course of a
standard multidrug antituberculosis regimen.
Prevention
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Bacillus Calmette–Guérin (BCG) vaccination of
schoolchildren, immunization of cattle and
pasteurization of milk.
Leprosy
Cause
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Caused by Mycobacterium leprae
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main route of infection is through nasal droplets
from cases of lepromatous leprosy, rarely from
eating infected armadillos.
Presentation
depends upon the immune response of the patient
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Those with a high resistance develop a
paucibacillary tuberculoid type
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Those with low resistance a multibacillary
lepromatous type
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between the extremes lies a spectrum of
reactions classified as ‘borderline’
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Nerve thickening is earlier and more marked in
the tuberculoid than lepromatous type.
The spectrum of leprosy: tuberculoid to lepromatous
Differential diagnosis
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Leprosy is a great imitator
Tuberculoid leprosy
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vitiligo
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pityriasis versicolor
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pityriasis alba
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post-inflammatory depigmentation of any cause
Borderline leprosy
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Sarcoidosis
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Granuloma annulare
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necrobiosis lipoidica.
Lepromatous leprosy
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Widespread leishmaniasis
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neurofibromatosis
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mycosis fungoides
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multiple sebaceous cysts
Investigations
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Biopsy of skin or sensory nerve.
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Skin or nasal smears, with Ziehl–Neelsen or
Fité stains, will show up the large number of
organisms seen in the lepromatous type.
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Lepromin test, of no use in the diagnosis of
leprosy but, once the diagnosis has been made, it
will help to decide which type of disease is
present (positive in tuberculoid type).
Treatment
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The emergence of resistant strains of M. leprae
means that it is no longer wise to treat leprosy with
dapsone alone.
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Dapsone in combination with rifampicin, and also
with clofazimine for lepromatous leprosy.
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Rifampin is rapidly bactericidal, making patients
non-infectious and able to return to the community.
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Tuberculoid forms are usually treated for 6 months;
multibacillary leprosy needs treatment for at least 1
year.
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Special care is needed with the two types of lepra
reaction that can occur during treatment.
Type 1 (reversal) reactions
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seen mainly in BT disease
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Lesions become red and angry, and pain and paralysis
follow neural inflammation.
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Treatment is with salicylates, chloroquine, nonsteroidal
and steroidal anti-inflammatory drugs.
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Nerve palsies need prompt treatment with
corticosteroids to preserve function.
Type 2 reactions
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common in lepromatous leprosy
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include erythema nodosum, nerve palsies,
lymphadenopathy, arthritis, iridocyclitis, epididymo-
orchitis and proteinuria.
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They are treated with the drugs used for type 1 reactions,
and also with thalidomide.
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The household contacts of lepromatous patients
are at risk of developing leprosy and should be
followed up.
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Child contacts may benefit from prophylactic
therapy and BCG inoculation.
The End