Encapsulated classic and follicular variants of papillary thyroid carcinoma: comparative clinicopathologic study.
To compare the clinicopathologic features of papillary thyroid carcinoma classic variant (PTC-CV) and papillary thyroid carcinoma follicular variant (PTCFV), with a focus on the encapsulated form.



In a retrospective search of computerized pathology files for 1996 to 1998, a cohort of 114 cases (58 cases of PTC-CV and 56 cases of PTC-FV) were selected for this study. Clinicopathologic data and long-term follow-up (serum thyroglobulin measurements, radiologic studies, and additional tissue sampling) through the date of compilation of study data were extracted from the medical records.



The median patient age at initial diagnosis was 46 years for the PTC-CV group and 45.5 years for the PTC-FV group. Complete tumor encapsulation was seen in 40 PTC-CV cases (69%) and in all PTC-FV cases (100%). A higher rate of tumor capsule invasion (CI), lymphovascular invasion (LVI), extrathyroidal extension, and lymph node metastatic lesions was seen in PTC-CV than in PTC-FV: CI, 26% versus 18%; LVI, 17% versus 4%; extrathyroidal extension, 19% versus 7%; and lymph node metastatic lesions, 68% versus 29%. Clinical, radiologic, or pathologic follow-up data were available in 36 PTC-CV cases (62%) and 34 PTC-FV cases (61%). The median duration of follow-up for the PTC-CV group was 10 years and for the PTC-FV group was 9 years. Tumor recurrence was found in 10 patients with PTC-CV (28%) and 2 with PTC-FV (6%). Distant metastatic lesions occurred in 3 patients with PTC-CV (8%) and 1 patient with PTC-FV (3%) (P = .17); of these, 2 cases of PTC-CV were encapsulated and showed CI, LVI, and lymph node metastatic lesions.



Our current study confirms previous reports that both encapsulated PTC-CV and encapsulated PTC-FV are indolent tumors and are associated with very low mortality.
Baloch
Zubair W
ZW
Department of Pathology and Laboratory Medicine, University of Pennsylvania Medical Center, Philadelphia, PA, USA. baloch@mail.med.upenn.edu
Shafique
Khurram
K
Flanagan
Melina
M
Livolsi
Virginia A
VA
D000328:Adult; D002277:Carcinoma; D002291:Carcinoma, Papillary; D018265:Carcinoma, Papillary, Follicular / Q000175:diagnosis*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D000077273:Thyroid Cancer, Papillary; D013964:Thyroid Neoplasms / Q000175:diagnosis