Macrofollicular variant of follicular thyroid carcinoma: a clinical, cytologic, morphologic, and image analysis study of a unique case.
Thyroid lesions composed of large follicles that contain abundant colloid are usually regarded as benign hyperplastic or adenomatous nodules both by fine-needle aspiration cytology and histology. In such cases, the pathologist is less likely to request a complete inclusion of the capsule into paraffin block and to look for vascular and/or capsular invasion, the only criteria that permit the differential diagnosis between a benign nodule and a follicular carcinoma. We report the first case of a follicular thyroid carcinoma composed predominantly (>90%) of macrofollicles with a surface area that was up to 5 times larger than the surface area of normal follicles, as calculated with an image analysis system. Capsular invasion was detected in 2 separate foci. The tumor was classified as a minimally invasive follicular carcinoma, macrofollicular variant. This case is detailed to highlight the potential pitfall that may arise from an incomplete histological analysis of a macrofollicular lesion, with particular attention paid to the differential diagnoses.
Bongiovanni
Massimo
M
Department of Pathology, Geneva University Hospital, 1211 Geneva, Switzerland. massimo.bongiovanni@hcuge.ch
Gremaud
Magali
M
Moulin
Cecile Stephan
CS
Scheidegger
Christof
C
Biton
Catherine
C
Clément
Sophie
S
D018263:Adenocarcinoma, Follicular / Q000473:pathology*; D000236:Adenoma / Q000473:pathology; D000328:Adult; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D006965:Hyperplasia / Q000473:pathology; D007090:Image Interpretation, Computer-Assisted; D007150:Immunohistochemistry; D013964:Thyroid Neoplasms / Q000473:pathology*