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. © 2009 Elsevier Inc. All rights reserved.
Bongiovanni, M., Gremaud, M., Moulin, C. S., Scheidegger, C., Biton, C., & Clément, S. (2009). Macrofollicular variant of follicular thyroid carcinoma: a clinical, cytologic, morphologic, and image analysis study of a unique case. Annals of Diagnostic Pathology, 13(2), 101–105. https://doi.org/10.1016/j.anndiagpath.2008.12.009