Ninety-four cases of encapsulated follicular variant of papillary thyroid carcinoma: A name change to Noninvasive Follicular Thyroid Neoplasm with Papillary-like Nuclear Features would help prevent overtreatment.
Encapsulated follicular variant of papillary thyroid carcinoma is a common thyroid gland cancer, with a highly indolent behavior. Recently, reclassification as a non-malignant neoplasm has been proposed. There is no comprehensive, community hospital based longitudinal evaluation of encapsulated follicular variant of papillary thyroid carcinoma. Ninety-four cases of encapsulated follicular variant of papillary thyroid carcinoma were identified in a review of all thyroid gland surgeries performed in 2002 within the Southern California Permanente Medical Group. All histology slides were reviewed and follow-up obtained. Seventy-five women and nineteen men, aged 20-80 years (mean 45.6 years), had a single (n=61), multiple (same lobe; n=20), or bilateral (n=13) tumor(s), ranging in size from 0.7 to 9.5 cm in diameter (mean 3.3 cm). Histologically, all cases demonstrated a well-formed tumor capsule, with capsular and/or lymphovascular invasion in 17 and no invasion in 77 cases. Lymph node metastases were not identified. The tumors had a follicular architecture, without necrosis or >3 mitoses/10 high-power fields (HPFs). Classical papillary thyroid carcinoma nuclear features were seen in at least three HPFs per 3 mm of tumor diameter, including enlarged, elongated, crowded, and overlapping nuclei, irregular nuclear contours, nuclear grooves, and nuclear chromatin clearing. Lobectomy alone (n=41), thyroidectomy alone (n=34), or completion thyroidectomy (n=19) was the initial treatment combined with post-op radioablative iodine in 25 patients. All patients were without evidence of disease after a median follow-up of 11.8 years. Encapsulated follicular variant of papillary thyroid carcinoma showed benign behavior, supporting conservative surgery alone and reclassification of these tumors to Noninvasive Follicular Thyroid Neoplasm with Papillary-like Nuclear Features (NIFTP).
Department of Pathology, Southern California Permanente Medical Group, Woodland Hills Medical Center, Woodland Hills, CA, USA.
Lester Dr
LD
Thompson
D018263:Adenocarcinoma, Follicular / Q000473:pathology* / Q000601:surgery; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002291:Carcinoma, Papillary / Q000473:pathology* / Q000601:surgery; D005260:Female; D006801:Humans; D008207:Lymphatic Metastasis / Q000473:pathology; D008297:Male; D008875:Middle Aged; D009626:Terminology as Topic; D013964:Thyroid Neoplasms / Q000473:pathology* / Q000601:surgery; D013965:Thyroidectomy; D016896:Treatment Outcome; D055815:Young Adult