Thyroid Gland, Follicle, Epithelium - Hyperplasia
comment:Hyperplasia of follicular epithelium may be focal, diffuse, or sometimes cystic. Focal or multifocal follicular hyperplasia can be present in a single or in a few follicles. Focal hyperplasia is not encapsulated and does not compress surrounding parenchyma, which differentiates it from benign tumors. Affected follicles may be small with minimal colloid or large and irregular with papillary projections of hyperplastic epithelium extending into the follicular lumen ( Figure 1 and Figure 2 ). Thyroid follicular hypertrophy and hyperplasia often occur together ( Figure 3 ). Hyperplasia characterized by crowding of follicular epithelium nuclei and minimal protrusion into the follicular lumen may occur ( Figure 4 ).
recommendation:Although follicular hyperplasia can occur spontaneously, it should be diagnosed and given a severity grade whenever present. Severity may be based on the percentage of the gland involved and the morphologic complexity of the hyperplasia. The nature and extent of the hyperplasia and whether it is unilateral or bilateral should be described in the pathology narrative. Distinction between focal, diffuse, and cystic thyroid follicular hyperplasia is recommended and should be included as a qualifier of the diagnosis. The nature of any associated hypertrophy in follicles with hyperplasia should not be diagnosed separately, unless warranted by severity. If not diagnosed, hypertrophy should be described in the pathology narrative.
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