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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