Follicular variant of papillary thyroid carcinoma: clinical-pathological characterization and long-term follow-up.
OBJECTIVE
Questions arise concerning the behavior and prognosis of the follicular variant of papillary thyroid carcinoma.


METHODS
Between 1990 and 2003, 92 patients with follicular variant of papillary carcinoma (group A) were enrolled in a long-term study and compared with control groups of follicular thyroid carcinoma (group B, 40 cases) and pure papillary thyroid carcinoma (group C, 99 subjects).


RESULTS
Gender (female/male), age, and follow-up duration (years, mean+/-standard error) in groups B, A, and C were 36/4, 43+/-3, 11+/-1.1; 79/13, 46+/-2, 9.5+/-0.7; and 82/17, 44+/-1, 10+/-0.6, respectively. At the time of diagnosis, the rates of extensive extra thyroidal local spread, bilateral lesions, and vascular invasion were higher in group A than in group C. The rate of metastasis tumors was higher in group A than in group C and was comparable in groups A and B. Complete remission was reported in 95% of group B patients, 98% of group C individuals, and in only 77% of group A subjects. Persistent stable lesions and progressive disease rates in groups B, A, and C were 2.5% and 2.5%, 15% and 8%, and 0% and 2%, respectively. The survival rates at the end of the study were 100% in all cohorts, but the cumulative dose of administered radioiodine in group A was higher than in group C and was comparable to that given in group B. Metastases dedifferentiation was observed only in the group A (three patients).


CONCLUSIONS
Follicular variant of papillary thyroid carcinoma may be more aggressive than previously considered and should be clearly distinguished from the two other forms of well-differentiated thyroid carcinoma.
Hagag
Philippe
P
Endocrine Institute, Assaf Harofeh Medical Center, Zerifin, Sackler Faculty of Medicine, Tel Aviv University, Israel. phagag@asaf.health.gov.il
Hod
Nir
N
Kummer
Esther
E
Cohenpour
Mehrzad
M
Horne
Tifha
T
Weiss
Mordechai
M
D000328:Adult; D018265:Carcinoma, Papillary, Follicular / Q000145:classification / Q000473:pathology / Q000628:therapy; D002454:Cell Differentiation; D018450:Disease Progression; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D012189:Retrospective Studies; D013964:Thyroid Neoplasms / Q000145:classification / Q000473:pathology / Q000503:physiopathology / Q000628:therapy