FINE-NEEDLE
ASPIRATION CYTOLOGY
WHEN THE
CLINICIAN SHOULD NOT TRUST A BENIGN RESULT
Fine-needle
aspiration (FNA) cytology – in association with ultrasonography (US) – are currently
the ‘gold-standard’ in the diagnostic evaluation of the patient with thyroid
nodule(-s) (TN). The false-negative rate for FNA ranges between 1 % and 3 %. However,
this problem may be more significant in the following clinical scenarios:
1.In large TNs
(> 4 cm). In this case, false-negative rate increases significantly (to 10 –
15 %). For this reason, FNA is not recommended in patients with large TNs.
2.In
patients with:
-a family history of thyroid cancer
-history of radiation exposure of the neck, in
particular during childhood
-cystic degeneration of the TN
3.When FNA
is not performed under ultrasonographic guidance (rare scenario today).
Ultrasonographic (US) guidance can confirm that the TN is actually being
sampled and target the most suspicious parts of the TN (i.e. the solid component
of a mixed [solitary and cystic] nodule). US guidance is especially important
for nonpalpable or posteriorly located TNs.
4.In the
presence of suspicious US findings, such as microcalcifications, irregular borders,
increased (chaotic) internal vasculature, cervical lymphadenopathy, ‘taller-than-wide’
morphology, etc
5.When
primary thyroid lymphoma is suspected (rapid enlargement of the thyroid, within
the last 1 – 3 months, with pressure symptoms from the aerodigestive tract,
hoarseness, superior vena cava syndrome etc). In these cases, diagnosis is
typically not possible based on the results of FNA and open (surgical) or –
alternatively – trucut biopsy will be required to establish the diagnosis.
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