Sampling, Assessment, and Reporting of Thyroid Follicular Lesions: Survey of 165 Pathologists
OK Kolman, PM Sadow, JL Hunt. Massachusetts General Hospital and Harvard Medical School, Boston, MA
Background: Diagnosis of follicular thyroid carcinoma is based on identification of capsular or vascular invasion, which is subject to sampling. There is no standard of care for what constitutes "adequate" sampling of follicular lesions. We surveyed current practices in sampling, assessment, and reporting of follicular lesions.
Design: An anonymous electronic web-based survey was successfully distributed to 800 pathologists.
Results: 165 (21% response rate) survey respondents comprised a diverse group of head and neck and/or endocrine specialists (31%) and general pathologists (47%), in academic (38%) and private practice (54%), with practice size ranging from 2800 to 320000 specimens per year (median 25000). 73% had >10 years of experience. Sampling: For initial sampling of follicular lesions, 38–79% submit the tumor capsule entirely (FIGURE), with the number who submit entirely inversely proportional to lesion size (p=0.01).
Those who do not initially submit the entire tumor capsule report increasing the number of sections with solid, trabecular, or insular growth pattern (59%, p=.04), necrosis (69%, p<.01), increased mitoses (63%, p=.002), and thick capsule (53%). Sampling is unchanged for macrofollicular (63%, p<.001), microfollicular (61%, p<.01) or Hürthle cell histology (57%). The most frequent definition of a thick capsule is 0.5-1 mm (38%). Assessment: In cases where the initial sections are suspicious for capsular or vascular invasion, the majority (73% and 65%) report their initial action is to obtain deeper levels; ∼70% obtain 3 levels. Reporting: 69% of specialists and 44% of non-specialists (p=.01) use a 3-tiered classification of minimally invasive, angio-invasive, and widely invasive follicular carcinoma. Over 60% do not specify the number of invasive foci, though 75% report invasion as “extensive” with 3 to 5 foci.
Conclusions: While significant variability exists in the current practice for sampling, assessment, and reporting of non-papillary follicular lesions, practice trends suggest submitting entire capsule of smaller lesions, selective additional sampling of larger lesions, and use of a 3-tiered classification system. Clinical research is required to establish a standard of care.
Monday, March 22, 2010 8:30 AM
Platform Session: Section H 1, Monday Morning