ARTICLE
Leishmaniasis is a protozoan disease with different
clinical manifestations depending both on the infecting species of Leishmania
and the immune response of the host. The infection, transmitted by the
bite of a sand fly infected with Leishmania parasites, may be restricted
to the skin in cutaneous leishmaniasis, limited to the mucous membranes
in mucosal leishmaniasis, or spread internally in visceral leishmaniasis
[1].
Cutaneous Leishmaniasis is endemic in the Mediterranean Basin. The typical
cutaneous lesion is the "Oriental Sore", an asymptomatic, solitary, erythematous
papule, which tends to become a nodule, centrally covered by yellow scabs,
although many clinical varieties of cutaneous leishmaniasis are known,
including impetiginoid, erysipeloid, vegetant, tuberous, verrucosus, nodular,
necrotic, lymphangitic or sporotrichoid forms [2].
The diagnosis of cutaneous leishmaniasis is established on the basis
of a typical lesion, a history of exposure and demonstration of the parasite.
Molecular methods, usually based on kinetoplast DNA, are being developed
and used increasingly to diagnose and type the infecting organism [3].
Although pentavalent antimonials remain a drug widely used in the treatment
of all forms of leishmaniasis, a great variety of both topical and systemic
treatments have been used in cutaneous leishmaniasis; however, the majority
of these modalities have been tested in non-controlled studies, with only
a few subjects, and the interpretation of results is usually difficult
due to the lack of a standard and well-accepted cure definition [4].
The authors describe an unusual clinical presentation of cutaneous leishmaniasis
occurring in an atopic subject and discuss the possible pathogenetic mechanisms
with particular attention to the role of nitric oxide in the immunological
control against intracellular parasites.
Case report
An 8-year-old otherwise healthy girl presented with a 4-month history
of a slowly growing, erythematous-edematous-infiltrative plaque with superficial
desquamation, involving all the nose skin surface (except for the root),
left upper eyelid and both zigomatic areas (Fig.
1).
The lesion was originally described as a small (about 1 cm in diameter),
round, asymptomatic, erythematous-infiltrative papule, localized in the
middle of the nose bridge. Patient's history was significant for personal
and familiar atopy.
Routine blood exams, including LDH, SGOT and CPK, were within normal
limits. Serum levels of total IgE, IgG and IgM were also normal. Search
for a number of serum autoantibodies (antinuclear, anti ENA, anti JO1
and anti Scl70) was negative.
Nailfold capillaroscopy and chest x-ray examination showed no alterations.
Histologic examination revealed a granulomatous infiltrate in the dermis,
consisting of lymphocytes, histiocytes and multinuclear giant cells; the
overlying epidermis appeared hyperkeratotic (Fig.
2).
Microscopic examination of the touch preparation from the biopsy specimen
(Giemsa stain, original magnification x 1,000) showed Leishmania amastigotes
as many small round-ovoid cells, with thin membranes, relatively large
nuclei and distinct rod-shaped kinetoplasts. The amastigotes were seen
within the histiocytes as well as extracellularly (Fig.
3).
Cutaneous leishmaniasis was diagnosed; the patient received therapy
with N-methylglucamine antimoniate, 1 ml twice a week, intralesionally,
with a gradual and progressive reduction of the swelling.
Physical examination 1 month later showed only a light erythematous
state of the left zigomatic area, followed by a complete resolution of
skin lesions.
Discussion
Cutaneous leishmaniasis is a relatively frequent pathology in the Mediterranean
basin and particularly in Sicily, caused by parasites of the genus Leishmania
carried by specific species of sandflies [5, 6]. In this region the disease
is mostly due to Leishmania infantum and vectors are the females of Phlebotomus
perniciosus [7].
The main reservoir of these parasites is represented by dogs and rodents,
so leishmaniasis tends to occur in rural areas. It usually affects unclothed
parts of the body, easily bitten by the sandfly, including the face, neck
and arms [8, 9].
The typical cutaneous lesion is an asymptomatic, solitary, erythematous
papule, which tends to become a nodule, centrally covered by yellow scabs.
The fully evolved manifestation remains substantially stable for some
weeks; spontaneous healing may occur, usually starting in the center of
the lesion and slowly spreading centrifugally.
Although many clinical varieties of cutaneous leishmaniasis are known,
including impetiginoid, erysipeloid, vegetant, tuberous, verrucosus, nodular,
necrotic, lymphangitic or sporotrichoid forms [2], the clinical presentation
together with a history of exposure is usually distinctive enough to suggest
the diagnosis in endemic areas; however it should be confirmed by demonstrating
the protozoa in a skin biopsy and/or in tissue smears.
We present this case because of its quite unusual clinical features,
possibly related to the reactivity of the atopic subject and the anatomic
characteristics of the affected area.
The specific immune response to Leishmania infection
is dependent on CD4+ lymphocytes; in particular, infected mice,
that naturally resolve their infectious Leishmania lesions, exhibit dominant
Th1 cell response [10]. Recent immunological studies, both in vitro
and in vivo, have demonstrated the role of nitric oxide (NO) as
an effector mechanism in the immunological control against intracellular
parasites. NO production depends on activation by IFNgamma synthesized
by TH1 cell whereas it is inhibited by IL-4, produced by the TH2 cell.
The altered balance between TH1 and TH2, typical of atopy, with consequent
production of IL-4, might contribute to the high susceptibility to opportunistic
infections and to the unusual clinical presentation [11].
Moreover, the laxity of the tissue and the great vascularization may
enhance cutaneous expression of the Leishmania infestation, producing
new aspects which add to the difficulty of diagnosis [12, 13].
Clinical differential diagnosis include lupus vulgaris, entomodermatosis,
dermatomyositis and urticaria. With regard to our patient, despite the
unusual clinical presentation, the origin from an endemic area, the localization
on an unclothed part together with the results of laboratory and instrumental
exams, especially histologic findings and microscopic evaluation of touch
imprint, are consistent with the diagnosis of cutaneous angio-lupoid leishmaniasis
[14, 15].
Several drug therapies are effective in the treatment of cutaneous leishmaniasis,
mostly using antimonials in localized forms [4, 16]. In our experience,
intralesional meglumine antimoniate is useful and manageable, with little
discomfort for patients and rapid clinical response. The selective mechanism
of inhibition of many enzymes, involved in parasite anaerobic metabolism,
and the low toxicity, when administered exclusively in the lesional area,
make it a safe, cheap and effective cure for this pathology [13].
.Article accepted on 22/7/02
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