[1267] Poorly Differentiated Oncocytic (Hurthle Cell) Follicular Carcinoma: An Institutional Experience

Shuting Bai, Zubair W Baloch, Kathleen T Montone, Virginia A LiVolsi. Hospital of the University of Pennsylvania, Philadelphia, PA

Background: According to Turin criteria, poorly differentiated thyroid carcinoma (PDTC) is defined based on growth pattern (solid and trabecular) and high grade features (nuclear pleomorphism, mitoses, and coagulative tumor necrosis). However, the cases reviewed in that study did not include oncocytic follicular carcinoma/Hurthle cell carcinoma (OFC/HCC). OFC/HCC is considered an oncocytic variant (OV) of follicular carcinoma characterized by large size (majority > 4.0 cm) tumors occurring at older age, frequent angioinvasion and distant metastases. In this study, we report our institutional experience with 15 cases of OV-PDTC.
Design: We examined a cohort of 324 cases of OFC/HCC (institutional pathology and consultation files searched from 1/2004 to 7/2012) and identified 15 cases (12 primaries and 3 neck recurrence) of OV-PDTC based on Turin criteria. Histologic slides were reviewed in all cases. Clinical follow-up was obtained from electronic medical records.
Results: The 15 cases of OV-PDTC occurred in 7 male and 8 female patients with average age of 70 yrs (range form 44 to 84 yrs). The primary size was available in 11 cases and 80% were larger than 4.0 cm (average 4.5 cm). In the primary thyroid tumors examined, 6 were encapsulated and 6 were widely invasive; lymph node metastases were seen in 3 and distant metastases in two patients at the time of thyroid resection. Extensive vascular invasion (5-15 foci) was noted in all cases. All tumors showed an admixture of oncocytic or Hurthle cells arranged on solid and trabecular growth pattern and aggregates of cells of small size with minimal eosinophilic cytoplasm; comprising 10-20% of the entire tumor mass. Immunohistochemistry was performed in 7 cases and the poorly differentiated component demonstrated minimal to weak staining for thyroglobulin. Clinical follow-up was available in 11 cases and ranged from 6 to 120 months (average 41 months). Distant metastases (lung, liver, brain, and bone) to one or more sites were seen in 9/11 (82%) patients; 2 (18%) of them had lung metastases at the time of thyroid surgery and 4 patients (36%) subsequently developed cervical lymph node metastases. Two patients had cervical lymph node recurrence only. Two patients died of the disease and 5 are alive either with tumor or free of tumor. The remaining patients are lost to follow-up.
Conclusions: The OV-PDTC is a distinct entity which can be identified on the basis of Turin criteria and the presence of a distinct “small cell” component. It is frequently associated with regional recurrence, distant metastases and can lead to tumor related demise.
Category: Head & Neck

Tuesday, March 5, 2013 9:30 AM

Poster Session III # 144, Tuesday Morning


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