Diagnosis of follicular
carcinoma is almost purely based on the presence of
capsular and/or vascular invasion.
Cytological features are not reliable.
Thus, the entire capsule should be submitted for
evaluation of invasion.
Tangential cut may create artificial capsular invasion
with entrapment of thyroid tissue in the capsule
Prior needle biopsy can cause entrapment of thyroid
tissue in the capsule or "invasion" outside of the main
nodule. Need to review the patient history, and also
look carefully at the possible needle track for
infarct-like glandular necrosis or hemosiderin deposits
It is very difficult to make the
diagnosis of follicular carcinoma on frozen (unless
there is clear evidence of capsular invasion) or FNA