Risk Classification of Follicular Pattern Lesions in Thyroid FNA (Fine Needle Aspiration) Cytology (Part 1: Benign Follicular Pattern Lesion vs. FN/SFN)

  • Kaori KameyamaEmail author
  • Eiji Sasaki


In thyroid cytology, when cell clusters of follicular pattern were seen,the following points are inportant. 1. If findings such as microvesicular chromatin (ground-glass appearance), nuclear grooves, or intranuclear cytoplasmic inclusions are observed in the nucleus, the lesion is a follicular variant of papillary carcinoma. 2. If the lesion is not a follicular variant of papillary carcinoma, the lesion is an adenomatous goiter if the cells are diverse (follicular cells, oxyphilic cells, macrophages, stromal cells, etc.). 3. If the cells are monotonous, then the lesion is a follicular neoplasm if it has a hemorrhagic background. 4. Even if the cells are monotonous, if a colloidal background is present, then the lesion is an adenomatous goiter.


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    Busseniers AE, Oertel YC. “Cellular adenomatoid nodules” of the thyroid: review of 219 fine-needle aspirates. Diagn Cytopathol. 1993;9:581–9.CrossRefGoogle Scholar

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© Springer Nature Singapore Pte Ltd. 2019

Authors and Affiliations

  1. 1.Department of Diagnostic PathologyKeio University HospitalTokyoJapan
  2. 2.Department of PathologyIto HospitalTokyoJapan

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