302 Bombay Hospital Journal, Vol. 54, No. 2, 2012
Anita Sharma*, Sudhamani S.**, Ajita Pandit***, V. M. Kiri****
*Lecturer, **Asso. Professor, ***Professor, ****Professor Head, Dr. D. Y. Patil Medical College, Navi Mumbai - 400705
Microfilariae in Lymph Node Aspirate
Abstract
Lymphatic filariasis is a major public health problem in India. It is unusual to find
microfilariae in fine needle aspiration cytology (FNAC) smears of lymph nodes
inspite of very high incidence in India. It is estimated that about 553.7 million 1people are at risk of lymphatic filariasis infection in 243 districts across India.
In the absence of clinical features of filariasis, FNAC may help in the diagnosis of
lymphatic filariasis. We present this case because of unusual occurrence of isolated
lymph node filariasis (occult filariasis) without microfilaraemia.
Introduction
ilariasis is largely confined to tropics Fand subtropics. Diagnosis is
conventionally made by demonstrating the
microfilaria in three consecutive night
blood samples. In early stages, fine needle
aspiration cytology (FNAC) of the enlarged
lymph nodes is a useful diagnostic tool and
may reveal the parasite.
Microfilaria in our case has been an
incidental finding on FNAC of cervical
lymph nodes without any clinical features
of f i lariasis or peripheral blood
microfilaraemia.
Case Report
A thirteen year old female student came with
complaints of dry cough and multiple cervical lymph
node swellings. There was no history of fever or
generalised lymphadenopathy. Provisional clinical
diagnosis was tuberculosis. On examination, the
lymph nodes were in the posterior triangle of right
side neck, firm, matted, each 3 x 3cms. There was no
local rise of temperature or skin changes.
Aspirate was thick creamy white. Papanicolaou
smears were prepared and they showed scattered
coiled microfilariae in a background of reactive
lymphoid cells and neutrophils (Figs. 1 and 2).
Multiple peripheral blood smears taken for
consecutive three nights showed no evidence of
microfilaria, but eosinophilia (13%) was noted.
Careful histopathological search of the lymph nodes
failed to show microfilaria.
Based on the above findings, a diagnosis of lymph
node filariasis in the absence of microfilaraemia was
made.
Fig. 1: 40X Pap smear showing partially coiled microfilaria in a background of inflammatory cells.
Fig. 2: 40X Pap smear showing coiled microfilaria.
Bombay Hospital Journal, Vol. 54, No. 2, 2012 303
Discussion
Microfilariasis is caused by nematodes
inhabiting blood vessels, lymphatic
system, connective tissues and serous
cavities of man and animals. The adult
females are viviparous giving birth to larva
known as microfilaria in the lymphatics of
man, the definitive host. The most
common species found in India is
Wucheria Bancrofti. Species diagnosis is 2by the study of larval forms.
Wucheria Bancrofti, also known as
Bancroft's filaria is a sheathed periodic
microfilaria with tail tip free from nuclei.
But in our case, the tail tip is not visualised
properly as the microfilariae are coiled and
therefore species identification was not
possible. The injurious effect by the larvae
on the human host is in the form of
lymphangitis which is the basic lesion in
classic filariasis. Filariasis is seen apart
from lymph nodes in lungs, liver and 2spleen.
Diagnosis of Filariasis is by either
direct evidence or by indirect immuno
allergic tests. Limited reports are available
in the literature attesting the importance
of FNAC as a diagnostic tool in the
diagnosis of filariasis in the early stages.
Histopathological examination may not 3demonstrate microfilaria. Microfilariae
may not be seen in peripheral blood due to
elephantiasis, lymphangitis, and early
stages of allergic manifestations and in 2occult filariasis.
It is said that in early allergic stage
microfilariae do not appear in peripheral
blood and hence diagnosis depends on
lymph node FNAC or biopsy adjacent to
the area of lymphangitis and/or by
2immunologic tests.
Even though rare case reports of
microfilariae found in the FNAC smears of 4other sites such as thyroid nodule,
pericardial fluid, bronchial aspirate and
breast lesions are available in literature,
majority were found in the axillary lymph 3,5nodes as incident finding. In our case,
there were multiple cervical lymph nodes
as the initial presentation without
evidence of lymphangitis.
Imaging studies of the lymph nodes
are of little help in the diagnosis of
microfilaria as the findings may not be 6conclusive.
In conclusion, absence of microfilaria
in peripheral blood does not rule out
filariasis. Histopathology of lymph nodes
may not always show microfilaria or adult
worm, as in our case. Therefore, FNAC is
recommended as an invaluable tool in the
diagnosis of lymphatic filariasis, even in
the absence of clinical features of filariasis.
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