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Bangladesh Journal of Medical Science Vol. 13 No. 01 January’14

Introduction
Among other tropical diseases, filariasis is a major
public health problem in the African and Asian sub-
continent. It is transmitted by the Culex mosquito
and is caused by two closely related nematodes:
Wuchereria bancrofti and Brugia malayi. Filariasis
affects the lymphatic system with a predilection for
lower limbs, retroperitoneal tissues, spermatic cord,
and epididymis1. Filaria can affect other sites rarely.
Though single or small number of cases on microfi-
laremia at various sites as lymphnode, breast lump,
bone marrow,bronchial aspirates, nipple secretion,
pleural and pericardial fluid, ovarian cyst fluid and
cervico vaginal smear have been reported, thyroid is
another site from which microfilaria has been isolat-
ed. So far only nine case reports are available. It is
estimated that approximately 600 million people are
living in areas endemic for lymphatic filariasis
Southeast Asia Region. There are approximately 60
million people infected in the region and approxi-
mately 31 million people have the clinical manifes-
tation of this disease2.
Here we present a patient with filariasis of the thy-
roid detected by Fine needle aspiration cytology
(FNAC) of thyroid gland.

Case Presentation
A 36-year-old female presented with a slowly
enlarging painless swelling of thyroid gland over a
period of two years. Clinically patient had no other
complain. Thyroid function was normal. On exami-
nation a 3×3 cm, firm, non-tender thyroid nodule
was palpable over left lobe. No cervical lymph node
was palpable. Fine-needle aspiration of the thyroid
nodule revealed blood mixed colloid. Slides were
stained with Leishman-Giemsa stain. 
Microscopic examination of the smear showed the
presence of microfilarial larvae with few mono-lay-
ered clusters of benign follicular cells in the back-
ground of blood mixed colloid. The microfilariae
had blunt head and pointed tail with a sheath project-
ed slightly beyond the extremities of the embryo
(Fig.1).  Somatic cells or nuclei appeared as granule
in the central axis of the body and were absent at the
tip of the tail. All the features distinguish M. ban-
crofti from the other sheathed larvae.

Discussion
Filariasis is a global problem. It is also a major
health problem in India3 .This patient also presented
as euthyroid state similar to the findings of  Kundu

Case report:
A rare case of microfilaria in thyroid  aspirate

Mondal RK1, Ray R2, Kawsar H3, Ali MS4.

Abstract
Filariasis is a major health problem in the Indian Subcontinent. Due to its nocturnal periodici-
ty it may be difficult even to demonstrate in the blood. In heavy parasitic load they may appear
in the blood, urine with chyle and at times in scrotal aspirates. It is very rare and unusual to
find microfilaria in thyroid aspirate. 
This case report of presence of microfilaria in thyroid aspirate suggest that careful screening is
important for thyroid lesions as patients may present with thyroid enlargement other than usual
thyroid lesions. 

Key words: microfilaria, thyroid, FNAC

Corresponds to: Dr.Rajib Kumar Mondal, Assistant Professor, Dept. of Pathology, Vill-Barjora,
Schooldanga, Po+ps-Barjora, Dist-Bankura, WestBengal, Pin-722202, India,
Email: rajibkmondal@yahoo.co.in

1. Mondal Rajib Kumar, Assistant Prof,BSMCH
2. Ray Rudranarayan, Assistant Prof,BSMCH
3. Kawsar Hena, PGT, BSMCH
4.Ali Md. Sadakkas, Resident Surgeon, NRS Medical College, Kolkata

DOI: http://dx.doi.org/10.3329/bjms.v13i1.14217
Bangladesh Journal of Medical Science Vol. 13 No. 01 January '14 Page 99-100



et al, Kar D.K. et al and Mohanti et al4,5,6. In no
case reported previously suspect of microfilaria was
made. All the cases were sent for FNAC for diagno-
sis of other primary lesions similar to our case2.
The clinical manifestations of lymphatic filariasis
may range from asymptomatic microfilariasis to
hydrocele, lymphangitis, lymphadenitis with high-
grade fever (filarial fever), and lymphatic obstruc-
tion7. In our case it presented with asymptomatic
thyroid swelling, similar findings have been noted
by study of  Mohanti et al and  Vargese et al6,8.
Microfilaria of thyroid has never been suspected in
any case reports including those cases where high
eosinophilia has been reported2.
There are eight identified species of filarial parasite
among them only three (i.e., W. Bancrofti, B. Malayi,

and Brugia timori) are known to cause lymphatic
filariasis . These are sheathed species. In India
microfilariae bancrofti and microfilariae malayi are
the commonly prevalent species. Species diagnosis
is made on the basis of morphology of the microfi-
laria. Microfilariae of B. Malayi are smaller than
those of W. bancrofti, possess secondary kinks
instead of a smooth curve, and unlike the latter, the
tip is not free of the nuclei9.

Conclusions
In conclusion, filariasis of the thyroid is an uncom-
mon condition and need a high index of suspicion
and careful screen of FNA smears especially in
asymptomatic patients belonging to endemic zones,
so as not to miss this incidental finding  especially in
patients from endemic areas .

References
1. Faust EC, Russell PF, Jung RC. Craig and Faust's

Clinical Parasitology, 8th ed. Philadelphia: Lea &
Febiger; 1970.

2. Chowdhary M, Langer S, Aggarwal M, Agarwal C.
Microfilaria in thyroid gland nodule. Indian J Pathol
Microbiol. 2008 ; 51(1):94-6  PMid:18417874
http://dx.doi.org/10.4103/0377-4929.40415

3. Park K.Textbook of Preventive and Social Medicine.
21st ed. Jabalpur: Banarsidas Bhanotn; 2011.

4. Kundu AK, Giri A, Ghosh G, Saha SR. Microfilaria in
a thyroid nodule which resolved on treatment.Trop
Doct. 2002 ;32(4):248  PMid:12405321

5. Kar DK, Agarwal G, Krishnani N, Mishra SK.
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PMid:11892028 

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PMid:18064692 

8. Varghese R, Raghuveer CV, Pai MR, Bansal R.
Microfilariae in cytologic smears: A report of six
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h t t p : / / d x . d o i . o r g / 1 0 . 1 1 5 9 / 0 0 0 3 3 3 7 5 5
PMid:8629415

9. Chatterjee KD. Parasitology. 13th ed. New Delhi: CBS
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