Nuclear enlargement and pleomorphism
Chronic lymphocytic thyroiditis - Case 75
The lack of prominent nucleoli decreases but does not exclude the possibility of an oxyphilic tumor. The risk of an oxyphilic variant of papillary carcinoma can be excluded because there was neither inclusion nor groove present. What about the risk of oxyphilic variant of follicular carcinoma? See case history.

Benign hyperplastic nodule - Case 50
The presence of pycnotic cells and small amount of colloid is the clue to avoid overinterpratation of atypical cells on the smear.

Benign hyperplastic nodule - Case 19
Oxyphilic cells dissociated - this is the cause of concern. But the presence of diffuse colloid and the lack of prominent nucleoli argue against the possibility being the lesion an oxyphilic tumor.

Benign hyperplastic nodule - Case 39
Regular monolayered sheets with vacuolisation and pronounced anisonucleosis. These properties are reassuring. Anisonucleosis itself is not enough to raise the possibility of a thyroid tumor.

   
 
In a hormonally active organ like the thyroid, the usual signs of nuclear atypia, i.e. anisonucleosis and pleomorphism has much less relevance than in other organs. The former has minimal importance in the everyday practice. Moreover, in certain cases even a monomorphous cellular pattern may raise the possibility of a follicular tumor.
As regards the latter, it is evident that malignant cells present more frequently pleomorphismism than benign cells. On the other hand, in contrast with many other organs, pleomorphism itself is not enough to give a malignant diagnosis in the thyroid.
It is essential to being aware of patient history in order to avoid overdiagnosis of atypical cells. Previous thyrostatic or radioiodine therapy, hormonal influences and first of all oxyphilic metaplasia may cause significant change not only in the size but even in the shape of cells. In certain cases to answer a simple question is enough to reach the goal: which type of malignancy could the atypia that can be seen on the smear belong to? Most if not all cases of papillary cancer presents inclusion or groove. The cellular arrangement in a medullary carcinoma lack follicular formation. As regards cases presenting atypia and microfollicular proliferation, consideration of the sonographic pattern is essential to a correct diagnosis.
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