The most common differential diagnoses of encapsulated thyroid lesions are macrofollicular adenoma, adenomatoid nodule
, follicular adenoma, follicular variant of papillary carcinoma and an encapsulated follicular carcinoma.
Thirteen (15.47%) were males, 33 (39.29%) had follicular adenoma, 38 (45.24%) had micro follicular adenomatoid nodule, 9 (10.71%) had micro follicular adenomatoid nodule in background of thyroiditis while 4 (4.76%) had follicular carcinoma.
Microfollicular adenomatoid nodule and follicular adenoma are the frequent thyroid gland lesions presenting with follicular pattern on routine histopathological examination.
Benign Adenomatoid nodule
, colloid nodule 106 (58.88) Hashimoto's thyroiditis 17 (9.44) Subacute thyroiditis 2 (1.11) III.
Diagnostic errors of thyroid FNA can also be caused by the mistakes of cytopathologists and the inherent nature of thyroid nodules due to overlapping cytologic criteria among hyperplastic adenomatoid nodule
in goiter, follicular adenoma, well-differentiated follicular carcinoma, and follicular variant of papillary carcinoma .
Follicular carcinoma must be distinguished from follicular adenoma, adenomatoid nodules
, the follicular variant of thyroid papillary carcinoma, medullary carcinoma, and other clear-cell tumors (parathyroid adenoma/carcinoma) or metastatic renal cell carcinoma.
Cytology specimen showing multinodular process with intervening colloid-rich thyroid tissue is often seen not only in follicular neoplasm but also in benign adenomatoid nodules
[1, 31], which may have been a cause for false-negative results.
Inconclusive FNAC results and diagnostic errors are unavoidable due to overlapping cytological features, particularly among hyperplastic adenomatoid nodules
, follicular neoplasms, and follicular variants of papillary carcinoma.
Fortunately, the vast majority of these nodules are benign (adenomas and adenomatoid nodules of multinodular goiters); approximately 2% to 12% are found to represent malignancy upon further work-up.
Pathologically, these follicular lesions consist of follicular adenomas, carcinomas, and cellular adenomatoid nodules. As these cannot be reliably distinguished by cytologic evaluation, surgical excision is required to make the distinction between these entities.
Metastatic deposits are identified at a higher frequency in abnormal glands--that is, those with adenomatoid nodules
, thyroiditis, and follicular neoplasms.
Many neoplasms are considered in the differential diagnosis, but the principal ones are follicular adenoma, follicular carcinoma, and medullary carcinoma; nonneoplastic considerations are diffuse hyperplasia (Graves' disease) and adenomatoid nodules