Thyroid carcinomas with a variable insular component: prognostic significance of histopathologic patterns.
BACKGROUND
An insular growth pattern may be observed focally both in papillary and follicular thyroid carcinoma. The aim of the current study was to determine whether a greater extension of the insular component (IC) influences different clinical and histologic features at diagnosis, and a different tumor aggressiveness in terms of frequency in the occurrence of metastases as well as survival.


METHODS
Thirty-three patients with histopathologic findings consistent with IC were included in the study. IC was focal (<50% of the tumor area) in 16 patients and predominant (>50% of the tumor area) in 17 patients. These 2 groups were compared with a control group of 66 patients with differentiated thyroid carcinoma.


RESULTS
At diagnosis, carcinomas with predominant IC differed from those with focal IC with regard to greater tumor size and a higher frequency of extrathyroidal extension and distant metastases. Patient follow-up ranged from 5 to 188 months. The cumulative rate of distant metastases was significantly higher in patients with predominant IC. At the time of last follow-up, carcinomas with predominant IC demonstrated a lesser frequency of disease-free outcome (P = .002) and a higher number of tumor-related deaths (P = .002), either when distant metastases were present (P = .03) or absent (P = .05) at the time of diagnosis.


CONCLUSIONS
The presence of predominant IC is associated with a poor prognosis in terms of ongoing disease or death. Predominant IC should be considered a separate entity from not only the classical papillary or follicular carcinomas but also the focal IC tumor.
Rufini
Vittoria
V
Department of Nuclear Medicine, Catholic University of Sacred Heart, Rome, Italy. v.rufini@rm.unicatt.it
Salvatori
Massimo
M
Fadda
Guido
G
Pinnarelli
Luigi
L
Castaldi
Paola
P
Maussier
Maria Lodovica
ML
Galli
Guido
G
D000368:Aged; D002277:Carcinoma / Q000473:pathology* / Q000556:secondary; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D053208:Kaplan-Meier Estimate; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D011237:Predictive Value of Tests; D011379:Prognosis; D013964:Thyroid Neoplasms / Q000473:pathology*