Pediatric Thyroid Carcinomas of Follicular Cell Origin: A Clinico-Pathologic Study of 42 Cases
Sadana Balachandar, Michael Rivera, Michael LaQuaglia, R Michael Tuttle, Charles Sklar, Ronald Ghossein. Memorial Sloan-Kettering Cancer Center, New York, NY
Background: Pediatric thyroid carcinomas (TC) of follicular cell origin are rare. Our aims are 1) to assess the prognostic value of histologic subtyping and other morphologic parameters in pediatric TC 2) Correlate the histologic findings with the presence of metastatic disease.
Design: 42 cases of pediatric TC of follicular cell origin presenting in children < 18 years old without history of radiation exposure were included. All tumors were subjected to a meticulous histopathologic examination.
Results: There were 31 (74%) females and 11 (26%) males with a median age of 13.4 years. The tumor histotype was distributed as follows: 17 (40%) classical papillary thyroid carcinoma (PTC), 7 (17%) encapsulated follicular variant (FV) PTC, 6 (14%) diffuse sclerosing variant (DSV) PTC, 5 (12%) tall cell variant PTC, 1 (2.5%) infiltrative FV PTC, 1 (2.5%) solid variant PTC, 1 (2.5%) unclassifiable PTC, 1 (2.5%) minimally invasive follicular carcinoma and 3 (7%) poorly differentiated (PD)TC. At presentation, cervical lymph node metastases (LNM) were found in 24 (57%) of cases and distant metastases (DM) in 8 (19%) of individuals. While age did not affect the LNM and DM rates, male patients had a higher incidence of LNM (p=0.0122) and DM (p=0.0195). DSV had a higher DM rate (4/6, 67%) than the remaining TC (4/36, 11%, p=0.0079). The LNM frequency was also more elevated in the DSV (6/6, 100%) compared to the rest of the TC (18/32, 50%; P=0.0292). Infiltrative TC had a very high LNM rate (24/26, 92%) while encapsulated non-infiltrative tumor lacked nodal metastases (0/16, p=0.0001). Distant metastases were present in 8 of 26 (31%) of infiltrative tumors while absent in encapsulated neoplasms (0/16, 0.0159).The presence of a positive margin and extensive extra-thyroid extension (ETE) strongly correlated with the presence of LNM (p<0.01) and DM (p<0.01). Primary tumor >4 cm had a higher DM rate (p=0.03). With a median follow up of 3.7 years, only 2 patients recurred: 1 infiltrative classical PTC with extensive extra-thyroid extension and metastatic PD in the LN; and 1 encapsulated FV PTC with focal angioinvasion and extensive capsular invasion. All 8 encapsulated TC without vascular invasion did not harbor metastases or recur.
Conclusions: DSV, infiltration, male gender, positive margins, extensive ETE and large tumor size are associated with the presence of DM in pediatric TC 2) Encapsulated TC without vascular invasion appear to behave in an indolent fashion in children.
Monday, March 4, 2013 2:00 PM
Proffered Papers: Section H, Monday Afternoon