What are the characteristic cytological features of papillary thyroid carcinoma?

In papillary thyroid carcinoma, the characteristic cytological features include a microfollicular growth pattern. This type of pattern is characterized by the presence of small follicles that may vary in size but are often accompanied by thin, delicate fibrous stroma. The architecture seen in this carcinoma can also exhibit branching or papillary structures, which are distinct and contribute to the diagnosis.

Additionally, while nuclear features such as nuclear grooves, inclusions, and overlapping are crucial in identifying papillary thyroid carcinoma, the mention of microfollicular arrangements specifically highlights the disorganized and irregularly arranged follicles that are typical of this malignancy. This contrasts with other options, where increased mitotic figures are not prominent in this tumor type, signet-ring cells are associated with other neoplasms (like gastric tumors), and rosette formation is seen in neuroendocrine tumors rather than thyroid carcinomas.

Understanding the microfollicular pattern helps pathologists and clinicians accurately differentiate papillary thyroid carcinoma from other thyroid lesions, reinforcing its significance in diagnosing this common endocrine malignancy.