Objective: The encapsulated follicular variant of papillary carcinoma (FVPC) was recently reported to have genetic alterations and biological behavior closer to follicular adenoma/carcinoma than classic papillary carcinoma and unencapsulated FVPC. The objective of this study is to alert cytologists to this new subtype and to report our experience. Study Design: Cytology of 41 cases of surgery-proven encapsulated FVPC was reviewed and correlated with histopathology and ultrasound findings. These cases were collected over 19 years from 188 aspirates reported as ‘suspicious or atypical, cannot exclude FVPC’ and from 245 aspirates reported as follicular neoplasm. Results: Thirteen aspirates had diffusely atypical nuclei, 20 aspirates had mixed normal and atypical nuclei, and 8 aspirates had no atypical nuclei. On histology, papillary nuclei were distributed focally in the second and third groups. Crowded, oval, clear nuclei occurred in nearly 80% of the cases, nuclear grooves occurred in 12.2%, and nuclear pseudoinclusions occurred in 4.9%. Capsular invasion without angioinvasion was present in 30% of encapsulated FVPCs, with angioinvasion in 17.5% and lymph node metastasis in 7.5%. Most encapsulated FVPCs were benign-appearing on ultrasound with round-to-oval, circumscribed nodules with a hypoechoic rim. Conclusions: Encapsulated FVPC is more difficult to recognize on fine-needle aspiration and ultrasound than unencapsulated FVPC.

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Pituitary carcinoma (PC) is a very rare entity (0.2% of all pituitary tumors), with only about 140 cases reported in English literature. There are no reliable histological, immunohistochemical or ultrastructural features distinguishing pituitary adenoma (PA) from PC. By definition, a diagnosis of PC is made after a patient with PA develops non-contiguous central nervous system (CNS) or systemic metastases. To date, only three cases of PC have been reportedly diagnosed on fine needle aspiration (FNA). Two of the reported cases were diagnosed on FNA of the cervical lymph nodes and one on FNA of the vertebral bone lesion. Herein, we present a case of PC, diagnosed on FNA of the liver lesion. In this case, we describe cytologic features of PC and compare them to histologic features of the tumor in the pituitary. Clinical behavior of tumor, pathogenesis of metastasis and immunochemical and prognostic markers will also be described.