Clinical Features Of Leprosy Notes

Clinical Features Of Leprosy Notes

Clinical Features:

The two main forms of leprosy show distinctive clinical features:

1. Lepromatous leprosy:

• The skin lesions in LL are generally symmetrical, multiple, slightly hypopigmented and erythematous macules, papules, nodules or diffuse infiltrates. The nodular lesions may coalesce to give leonine facies appearance.

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• The lesions are hypoaesthetic or anaesthetic but the sensory disturbance is not as distinct as in TT.

2. Tuberculoid leprosy:

• The skin lesions in TT occur as either single or as a few asymmetrical lesions which are hypopigmented and erythematous macules.
• There is a distinct sensory impairment.

Long term cases of either type may develop secondary amyloidosis. Anti-leprosy vaccines have been developed but are undergoing human trials yet. Since the incubation period of leprosy is quite long, the efficacy of such vaccines will be known after a number of years.

Leprosy:

• Leprosy or Hansen’s disease is a chronic infectious disease that affects mainly the coolerb parts of the body such as the skin, mouth, respiratory tract, eyes, peripheral nerves, superficial lymph nodes and testis.
• The disease is caused by Mycobacterium leprae which closely resemble Mycobacterium tuberculosis but is less acid-fast and has characteristic neurotropism.
• The disease spreads by close contact for a long duration, often lasting for several years. Based on clinical, pathologic and immunologic features, leprosy is classified in to polar tuberculoid (high resistance), polar lepromatous (low resistance), and borderline towards either type.
• A few variants are reactional (type I upgrading and downgrading, type II or ENL) histoid, and pure neural leprosy.
• The lepromatous type has foam cell granulomas (multibacillary on lepra stain) while the tuberculoid type has epithelioid cell granulomas (paucibacillary on lepra stain).

Syphilis:

Syphilis is a venereal (sexually-transmitted) disease caused by spirochetes, Treponema pallidum, characterised by episodes of active disease interrupted by periods of latency.

Other treponemal iseases are yaws, pinta and bejel. The word ‘syphilis’ is derived from the name of the mythological handsome boy, Syphilus, who was cursed by Greek god Apollo with the disease.

Causative Organism:

T. pallidum is a coiled spiral filament 10 µm long that moves actively in fresh preparations.

The organism cannot be stained by the usual methods and can be demonstrated in the exudates and tissues by:

• Dark ground illumination (DGI) in fresh preparation,
• Fluorescent antibody technique
• Silver impregnation techniques, and
• Nucleic acid amplification technique by PCR.

The organism has not been cultivated in any culture media but experimental infection can be produced in rabbits and chimpanzees. The organism is rapidly destroyed by cold, heat, and antiseptics.

Incidence:

Since the advent of penicillin therapy in 1943, syphilis has shown a decline in incidence. However, the disease continues to be a global health problem. Most commonly affected regions in the world are in Sub-Saharan Africa, South America, China and South East Asia.

Male homosexuals are at greater risk in many European countries. Syphilis in pregnant women and adverse outcome of pregnancy (e.g. stillbirths, neonatal and early foetal death, and baby born with syphilis) are significant health problems in some countries such as China.

Immunology And Tests:

T. pallidum does not produce any endotoxin or exotoxin. The pathogenesis of the lesions appears to be due to host’s immune response.

Besides direct demonstration of the organism discussed above, there are two types of serological tests for syphilis: treponemal and non-treponemal.

1. Treponemal serological tests: 

These tests measure antibody to T. pallidum antigen and are more useful and sensitive for the diagnosis of syphilis:

• Fluorescent treponemal antibody-absorbed (FTA-ABS) test.
• Agglutinin assays for example Microhaemagglutination assay for T. pallidum (MHA-TP), and
• Serodia TP-PA; the latter is more sensitive.
• T. pallidum passive haemagglutination (TPHA) test.

2. Non-treponemal serological tests:

These tests measure non-specific reaginic antibodies IgM and IgG immunoglobulins directed against cardiolipin-lecithin-cholesterol complex and are more commonly used. These tests are as under:

• Reiter protein complement fixation (RPCF) test: Test of choice for rapid diagnosis.
• Venereal Disease Research Laboratory (VDRL) or Rapid Plasma Reagin (RPR) test:
• Wassermann described a complement fixing antibody against antigen of human syphilitic tissue.

This antigen is used in the Standard Test for Syphilis (STS) in Wassermann complement fixing test and VDRL test.

Mode Of Transmission:

• Syphilitic infection can be transmitted by the following routes:
• Sexual transmission (heterosexual or homosexual) is the most common route of infection and results in lesions on glans penis, vulva, vagina, cervix and rectum.
• Intimate person-to-person contact with lesions on lips, tongue or fingers.
• Transfusion of infected blood.
• Materno-foetal transmission in congenital syphilis if the mother is infected.

In view of similarity in mode of transmission and high-risk population, HIV infection and syphilis frequently coexist.

Stages Of Acquired Syphilis:

Acquired syphilis is divided into 3 stages depending upon the period after which the lesions appear and the type of lesions. These are: primary, secondary and tertiary syphilis.

Primary Syphilis:

• A typical lesion of primary syphilis is chancre which appears on the genitals or at extra-genital sites in 2-4 weeks after exposure to infection . Initially, the lesion is a painless papule which ulcerates in the centre.
• The fully-developed chancre is an indurated lesion with central ulceration accompanied by regional lymphadenitis. The chancre heals without scarring, even in the absence of treatment.

Histologically: The chancre has the following features:

• Dense infiltrate of mainly plasma cells, some lymphocytes and a few macrophages.
• Perivascular aggregation of mononuclear cells, particularly plasma cells (periarteritis and
  endarteritis).
• The proliferation of vascular endothelium.

Antibody tests are positive in 1-3 weeks after the appearance of chancre. Spirochetes can be demonstrated in the exudates by DGI.

Secondary Syphilis:

• Inadequately treated patients of primary syphilis develop mucocutaneous lesions and painless lymphadenopathy in 2-3 months after the exposure.
• Mucocutaneous lesions may be in the form of the mucous patches on mouth, pharynx and vagina, and generalised skin eruptions and condyloma lata in the anogenital region.

Antibody tests are always positive at this stage. Secondary syphilis is highly infective stage and spirochetes can be easily demonstrated in the mucocutaneous lesions.

Tertiary Syphilis:

After a latent period of appearance of secondary lesions and about 2-3 years following first exposure, tertiary lesions of syphilis appear. Lesions of tertiary syphilis are much less infective than the other two stages and spirochaetes can be demonstrated with great difficulty.

These lesions are of 2 main types :

1. Syphilitic gumma:

It is a solitary, localised, rubbery lesion with central necrosis, seen in organs like liver, testis, bone and brain. In the liver, the gumma is associated with scarring of hepatic parenchyma (hepar located).

Histologically: The structure of gumma shows the following features:

• Central coagulative necrosis resembles caseation but is less destructive so that outlines of necrosed cells can still be faintly seen.
• Surrounding zone of palisaded macrophages with many plasma cells, some lymphocytes, giant cells and fibroblasts.

2. Diffuse lesions of tertiary syphilis: 

The lesions appear following widespread dissemination of spirochetes in the body. The diffuse lesions are predominantly seen in cardiovascular and nervous systems.

Briefly, these lesions are as under:

• Cardiovascular syphilis It mainly involves thoracic aorta. The wall of aorta is weakened and dilated due to syphilitic aortitis and results in aortic aneurysm, incompetence of aortic valve and narrowing of mouth of the coronary ostia.
• Neurosyphilis It may manifest as:
  • Meningovascular syphilis affects chiefly the meninges, tabes dorsalis affecting the spinal cord, and
  • General paresis affecting the brain.

Congenital Syphilis:

Congenital syphilis may develop in a foetus of more than 16 weeks gestation who is exposed to maternal spirochetaemia.

Following major morphologic features are seen either at birth or develop subsequently:

• Saddle-shaped nose deformity due to destruction of bridge of the nose.
• Characteristic ‘Hutchinson’s teeth’ which are small, widely spaced, peg-shaped permanent teeth.
• Mucocutaneous lesions of acquired secondary syphilis.
• Bony lesions like epiphysitis and periostitis.

• Interstitial keratitis with corneal opacity.
• Diffuse fibrosis in the liver.
• Interstitial fibrosis of lungs.
• If the foetus with congenital syphilis is born dead, it is premature, with macerated skin, enlarged spleen and liver, and with syphilitic epiphysitis.

Histologically:

The basic morphology of lesions in syphilis is seen in all the affected organs i.e. perivascular plasma cell-rich inflammatory infiltrate and endothelial cell proliferation. Many spirochetes can be demonstrated in involved tissues.

Syphilis:

• Syphilis is a venereal (sexually-transmitted) disease caused by spirochetes, Treponema pallidum, transmitted most often by sexual route.
• The organism can be demonstrated directly in tissue fluids by dark ground immunisation, fluorescent method. Supportive laboratory tests are antibody tests such as VDRL, STS, FTA.
• Syphilis has 3 clinicopathologic stages: primary, secondary and tertiary. A characteristic feature in these lesions is plasma cell-rich microscopic morphology.
• Typical lesion of primary syphilis is chancre which appears on genitals or at extra-genital sites in 2-4 weeks after exposure to infection. These lesions are positive for spirochetes.
• Secondary syphilis has mucocutaneous lesions and painless lymphadenopathy. Spirochetes may be seen in the lesions.
• Tertiary stage occurs after a latent period lasting 2-3 years and its lesions are in form of gummas (in the liver or testis), and as diffuse lesions (cardiovascular and neurosyphilis).
• Newborn babies with congenital syphilis have saddle nose deformity and may develop widely-spaced teeth later.