METHODS
Preoperative diagnosis of a hydatid cyst of thyroid origin can be
challenging, as they can mimic tumors, abscesses, and other
space-occupying thyroid lesions such as thyroglossal cysts and branchial
cleft cysts (4) (9).
Complete blood count(CBC), thyroid function test, renal function test,
blood sugar, erythrocyte sedimentation rate (ESR), and C-reactive
protein (CRP) were within normal limits. Ultrasonography (USG) of neck
revealed a large multiloculated heterogeneous, anechoic lesion measuring
8.1 cm x 4 cm x 5 cm in left thyroid lobe and was designated a TI-RADS
(Thyroid Imaging Reporting and Data System) -3 lesion[Figure
1 ]. The other lobe and lymph nodes were normal. With a differential
of thyroid nodule, Fine needle aspiration cytology (FNAC) was performed
which yielded 18 ml of granular to clear watery fluid. Post FNAC period
was uneventful. Cytocentrifuged Giemsa stained and unstained smears
showed multiple protoscolices having rostellum containing rows of
refractile hooklets[Figure 2 ]. Numerous free hooklets,
fragmented laminated membranes of ectocyst and germinative layer were
identified. Refractile hooklets had claw-like appearances with pointed
one end and bifid another end[Figure 2 ]. Enzyme-Linked
Immunosorbent Assay (ELISA) was positive for Echinococcus with
serum IgG levels of 13 Net Titers Units (NTU). Detailed computed
tomography (CT) scan showed lesions that were limited to the thyroid. On
detailed questioning, the patient gave no past history of hydatid cyst
disease or similar symptoms in family members. A final diagnosis of the
primary hydatid cyst of the thyroid was made.