Pitfalls of Frozen Section Diagnosis for Paraganglioma: A Clinicopathologic Analysis and Review of the Literature.

Few paraganglioma (PG) cases include frozen section diagnoses, and therefore, the accuracy of frozen section diagnosis for PG remains unknown. To better understand the histologic characteristics and pitfalls of frozen section findings for PG, 15 PG cases with frozen section diagnoses were selected from 12 articles through PubMed (1984-2015). In addition, we included 3 cases of PG for which intraoperative consultations were requested during a 5-year period (2012-2016) in 2 hospitals. Seven PGs were from the thyroid; 2 from the pancreas; 4 from the mediastinum, retroperitoneum, or mesentery; 1 from the middle ear; and 4 from the urinary bladder (UB). Out of 18 PGs, correct diagnoses were rendered in only 2 cases, and no thyroid or UB PGs were correctly diagnosed on intraoperative consultation. Thyroid PGs were frequently misdiagnosed as medullary thyroid carcinomas (4/7, 57%) and UB PGs were frequently misdiagnosed as malignancies.