CYSTIC
LESION OF THE NECK MAY BE A CLINICAL MANIFESTATION OF PAPILLARY THYROID CANCER
AND MIMIC AN APPARENTLY BENIGN CYST
Although
the vast majority of cystic lesions of the neck are benign (such as branchial
cleft cysts, dermoid cysts, teratoma, epidemoid cysts, cystic hygromas etc), occasionally
they may be a clinical manifestation of papillary thyroid cancer (PTC, the most
common type of thyroid cancer). In this case, cystic lesions represent a
metastatically involved lymph node which underwent central liquefaction with
cystic degeneration. This is a common phenomenon in PTC, since approximately 40
% (reported range, 21 – 50 %) of all lymph node metastases have the tendancy to
completely cavitate a lymph node by cystic degeneration and thus may mimic an apparently
benign cyst of the neck. Moreover, in a small but significant percentage of
patients with PTC, lymph node metastases may be the sole or initial
manifestation of the disease (the so-called ‘occult’ thyroid cancer). More
rarely, these ‘cystic lesions’ may be due to cystic degeneration of ectopic
thyroid tissue. Only 5 % of intrathyroid PTCs are cystic, but in this case a
solitary component typically coexists. Fine-needle aspiration (FNA) should be
performed to establish the diagnosis. The fluid aspirated is typically acellular
and therefore cytology is often non-diagnostic. Thyroglobulin concentration (Tg)
should be measured in the aspirate. Detectable or high Tg levels support the
diagnosis of thyroid cancer (cystic degeneration of involved lymph node[-s]).
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