High Rates of Synchronous Oncocytic Neoplasms and Papillary Thyroid Carcinomas: Are We Missing Something?

Papillary thyroid carcinoma (PTC) incidence in cadaveric and benign disease studies is 9%-15%, but coexistence of PTC and oncocytic neoplasms (ONs) has not been described. We hypothesized that rates of PTC concurrently with ON would be similar to the general population. If a difference in rates is detected, we hypothesized that tumor proximity could signal etiologic influences predisposing dual neoplasia.

A single-institution database was queried for patients who underwent surgery and were found to have oncocytic carcinoma (OC) or oncocytic adenoma (OA) between 2012 and 2022 (n = 310). Concurrent PTC was classified by location relative to the oncocytic tumor as homotopic (same anatomic locus) or heterotopic (different locus). Because the database is restricted to ON, all comparisons were conducted within the oncocytic cohort; patients with OA or OC without concurrent PTC served as internal comparators for clinical, pathologic, and molecular characteristics across groups. Multivariable logistic regression assessed associations between concurrence and age, sex, oncocytic subtype, tumor size, and homotopy/heterotopy.

Twenty-six point seven percent of the 86 OC patients had concurrent PTC, which did not differ significantly from the 25.7% concurrence rate among the 225 OA patients (P = 0.89). The median PTC size was 0.4 cm (0.2-0.9) and did not differ between OC and OA (P = 0.45). Homotopic versus heterotopic distribution showed no significant differences in prevalence among patients with ON (P = 0.42). In multivariable logistic regression adjusting for age, oncocytic tumor size, and OC versus OA, male sex was associated with higher odds of concurrent PTC and homotopic PTC, while age, tumor size, and oncocytic subtype were not significant predictors. Mutation profiles and calculated risk of malignancy did not differ by concurrence with PTC, OA versus OC, or by tumor location.

Concurrent PTC occurred in ∼26% of ON, substantially higher than the 9%-15% expected in the general population. Concurrence does not appear dependent on tumor type (OA versus OC) or proximity (homotopy versus heterotopy). Further research into this synchronous relationship and molecular or environmental drivers is warranted.