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Abstract
Purpose:
The follicular variant of papillary thyroid carcinoma (FVPTC) is difficult to diagnose due to pathologic features. There is also debate on the optimal extent of surgery. We separated FVPTC into two groups and compared the clinical features in an attempt to apply the treatment.
Methods:
All 40 patients with FVPTC who were diagnosed between 1990 and 2009 were reviewed and separated into two groups, an encapsulated group and an infiltrative group, based on whether a capsule was formed or infiltration occurred. These two different subtypes of FVPTC were compared on the traits of sensitivity of diagnosis and clinicopathologic features.
Results:
After review by a pathologist, 21 of 40 patients (55%) were found to have encapsulated tumors, and 18 patients (45%) had infiltrative tumors. There was no difference in age, sex, or size. Patients with encapsulated FVPTC had a significantly lower rate of lymph node metastasis (4.5%), multicentric tumors (18.2%), and thyroid capsular invasion (9.1%) compared with the infiltrative tumor group (50%, 50% and 50%, P＜0.05). There was no difference in FNA sensitivity between the two groups, but the sensitivity to frozen biopsy was higher in the infiltrative group. There was no recurrence in the encapsulated group, but 4 patients (22.2%) experienced recurrence in the infiltrative group.
Conclusion:
FVPTC can be separated into two subgroups by histologic features, and there are some clinicopathologic differences between the two groups. Patients who had encapsulated FVPTC had a lower rate of lymph node metastasis, multicentric tumors, and thyroid capsular invasion. They also showed a lower rate of recurrence than the infiltrative group. It is suggested that the encapsulated group can be treated with limited surgery and the infiltrative group needs aggressive treatment.
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Fig. 1
Histologic section of FVPTC. (A) FVPTC shows nuclear features of PTC, (B) FVPTC shows follicle formation. FVPTC = follicular variant of papillary thyroid carcinoma.
Fig. 2
Histologic findings according to subgroups of FVPTC. (A) Encapsulated type tumor is surrounded by a capsule, (B) Infiltrative type shows no capsule and invasive pattern. FVPTC = Follicular variant of papillary thyroid carcinoma.
Table 1.
Comparison of clinicopathological features according to histologic subgroups of the FVPTC
Table 2.
Diagnosis of FNA according to histologic subgroup of FVPTC
Table 3.
Diagnosis of frozen biopsy according to histologic subgroups of FVPTC
Table 4.
Treatment of histologic subgroups of FVPTC
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