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Cutaneous
Leishmaniasis:
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1.
Acute lesions:
Present as a papule or nodule. The
lesion may ulcerate and heal leaving a scar.
Clinical differential diagnosis : Deep fungal infection and atypical
mycobacteria.
Microscopic feature:
- Dense dermal infiltrate of
lymphocytes, plasma cells, histiocytes, epithelioid cells and
occasionally eosinophils and giant cells. Sometimes neutrophils are
present throughout the reticular dermis.
- Numerous parasitized macrophages. The organisms are round to oval
basophilic structures with eccentrically located kinetoplast.
- The parasites lack capsule (D/D Histoplasma capsulatum)
- Organisms located at the periphery of the macrophages-"marquee"sign
- Oedema in the upper part of the dermis (+/-).
- Epidermis- Shows hyperkeratosis & acanthosis but sometimes
atrophy. May be ulcerated.
2. Chronic lesions:
Usually single sometimes multiple,
non ulcerated raised plaques. Persists for 1 to 2 years.
Microscopic
features:
- Parasitized macrophages are reduced in number
- Small tuberculoid granulomas composed of epithelioid cells ,
histiocytes and occasional giant cells.
- Epidermis shows atrophy
- Mild to moderate mononuclear infiltrate (lymphocytes & plasma cells)
near the granuloma together with fibrosis and telangiectasia.
Differential
diagnosis:
i) Lupus vulgaris ; ii)
Tuberculoid leprosy - Granulomas are elongated-present along
neurovascular plexuses.
3. Recidivous (lupoid) form:
Erythemous papules often present at
the periphery of a scar of a healed acute lesion.
Clinically resemble lupus vulgaris.
Microscopic
features:
Consists of tubercles surrounded by lymphocytes, histiocytes & giant
cells. There is no necrosis.
Occasional plasma cells. Organisms are fewer in number and found only
after careful examination of the section.
Differential
diagnosis :
Lupus vulgaris & tuberculoid leprosy.
4. Disseminated
anergic form:
Primary diffuse cutaneous
leishmaniasis.
Clinical presentation: Widespread nodules and macules without
ulceration.
There no involvement of other viscera.
Microscopic
features:
Consists of dense diffuse dermal
mixed inflammatory cellular infiltrate together with numerous
parasitized macrophages.
Differential
diagnosis:
Lepromatous leprosy- Consists of histiocytes
with bluish gray cytoplasm-confirmed by Fite's stain.
Mucocutaneous
Leishmaniasis
Initially lesions
resemble cutaneous leishmaniasis.
In some cases destructive ulcerative lesions develop at the
mucocutaneous junctions of larynx, nasal septum, anus and vulva.
Microscopic
features:
Parasitized macrophages are reduced in number. There may be occasional
tuberculoid granulomas.
Presence of necrosis with reactive response is a favourable prognostic
feature.
Visceral
Leishmaniasis (Kala-azar):
Parasites invade
macrophages throughout the reticuloendothelial system and cause severe
systemic marked by hepatomegaly, lymphadenopathy, pancytopenia, fever
and weight loss. Often there is hyperpigmentation of the skin in the
extremities. 'Kala-azar' is a Hindi word meaning black fever. Post-
kala-azar dermal leishmaniasis (PKDL) develops in about 5% of cases of
visceral leishmaniasis.
It is mainly seen in Sudan and India.
PKDL follows visceral leishmaniasis after an interval of 0-6months in
Sudan and 2-3 years in India.
The patient presents with areas of erythema (face), macules (trunk)
and nodules (face and limbs). The rash starts around the mouth and
then spreads to the rest of the body.
Clinically the differential diagnosis is leprosy (no loss of sensation
in PKDL). Cases have also been reported in HIV (+) patients.
Microscopic
features: A dense infiltrate of inflammatory cells composed of lymphocytes,
plasma cells, macrophages, epithelioid cells.
Occasionally neutrophils and eosinophils are present. In nodular
lesions the inflammatory infiltrate may be
present throughout the reticularis dermis.
The parasites (Leishman Donovan bodies) can be easily detected by
Giemsa stain.
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