Thyroid Paraganglioma: “Naked” Nuclei as a Clue to Diagnosis on Imprint Cytology

Abstract

A cytologic diagnosis of paraganglioma of the thyroid is difficult to make because the thyroid gland is an unusual location for such a tumor and the cytologic findings overlap with other benign and malignant thyroid tumors. We report the case of a 28-year-old female presenting with a solitary mass of the right thyroid gland. A diagnosis of paraganglioma was made on the resected specimen. At the time of tumor resection, imprint cytology was performed. The imprint was hypercellular with cohesive sheets of round cells showing anisokaryosis and anisocytosis. Moreover, there was a second cell type consisting of oval nuclei with dispersed nuclear chromatin present within the sheets and separate as "naked" nuclei. By immunohistochemistry, the cohesive round cells were positive for chromogranin A, indicating chief cells. The naked nuclei were positive for S-100 protein, indicating sustentacular cells. To the best our knowledge, this is the first case report describing naked nuclei as a cytologic feature of paraganglioma. Identification of sustentacular cells provides a clue for the cytologic diagnosis of paraganglioma.

Thyroid paraganglioma: A diagnostic pitfall in thyroid FNA

“…On immunohistochemistry, HTT is positive for TTF-1, thyroglobulin, and paired box 8 (PAX-8) and shows membranous expression of Ki-67. 23 Intranuclear…”

“…24 On immunohistochemistry, papillary thyroid carcinoma would be positive for TTF-1, thyroglobulin, PAX-8, CK19, and HBME, whereas paraganglioma would be negative. 23 Of note, most thyroid paragangliomas may also be misdiagnosed on intraoperative frozen sections as follicular carcinoma, Hurthle cell carcinoma, MTC, metastatic carcinoma, or they may end up being deferred. 25,26 Three cases in our series that had an intraoperative frozen section were incorrectly reported as a follicular lesion, cellular lesion best deferred to permanent sections, and suspicious for MTC.…”

Thyroid paraganglioma accompanied by lymph node metastasis or trachea invasion: A case report

“…TP is supposed to be derived from the inferior laryngeal paraganglion and then migrate into the thyroid lobe with embryologic development ( 17 ). This embryologic origin explains that the cytologic characteristics of TP are similar to other neuroendocrine lesions of the thyroid, including C-cell tumors (C-cell hyperplasia and MTC) and follicular-derived tumors (follicular and papillary thyroid carcinoma) ( 5 , 16 ).…”

Comparative study of imprint cytology and histopathology of soft tissue tumors

“…reported that the sustentacular cells that surround the nests of tumor cells in paraganglioma appear as naked nuclei in cytologic smears and they may provide a valuable clue to the diagnosis. [ 14 ]…”