Conference Coverage

Bethesda system underpredicts malignancy in pediatric thyroid tumors


 

REPORTING FROM ATA 2019

Pediatric thyroid nodule cytopathology classified according to the Bethesda system and tracked over a 16-year period at a single center showed a higher rate of malignancy than that reported in adults.

Especially for nodules that fall into indeterminate categories, “the rate of malignancy in thyroid nodules is higher [in pediatric patients] than that reported in adults,” said Wen Jiang, MD, of the University of California San Diego and Rady Children’s Hospital, also in San Diego.

Current pediatric guidelines recommend that thyroid fine-needle aspiration (FNA) be performed only under ultrasound guidance, noted Dr. Jiang, a pediatric otolaryngologist, at the annual meeting of the American Thyroid Association. In addition, the Bethesda thyroid cytopathology system should be used to report FNA cytology results, and when cytopathology of FNA for a thyroid nodule is indeterminate, thyroid lobectomy is preferred over repeat FNA for most children with thyroid nodules.

To assess how well pediatric patients fared using the Bethesda system for thyroid cytopathology, Dr. Jiang and colleagues performed a retrospective review of children with thyroid nodules who received FNA at Rady Children’s Hospital during 2002-2018. The investigators used the Bethesda system to classify FNA results.

In addition to collecting the initial cytologic findings and demographic data, Dr. Jiang and colleagues also tracked repeat cytology and histopathology, as well as any radiographic and clinical follow-up data that were available.

A total of 203 cytologic samples were available from 171 patients. In all, 50 patients (29.2%) had malignancy. The mean age was about 15 years (range, 6-18 years), and the ratio of 140 female to 31 male participants was 4.5:1.

All but 21 of the samples were performed under ultrasound guidance. The nondiagnostic rate for ultrasound-guided samples was 11.5%, and for those obtained without use of ultrasound – which occurred in older cases – the nondiagnostic rate was 38.5%. “Ultrasound guidance improves the diagnostic rate,” said Dr. Jiang, adding that incorporation of on-site adequacy testing also “significantly decreased the nondiagnostic rate over the study period.”

The Bethesda system has the following six diagnostic categories, with each accompanied by follow-up recommendations in the adult population.

  • Category I is nondiagnostic, and a repeat ultrasound-guided FNA is recommended for adults in this category.
  • Category II is benign. Patients with these nodules should receive clinical follow-up and repeat ultrasound examination.
  • Category III nodules may show atypia of undetermined significance or be judged a follicular lesion of undetermined significance. Here, adult management options include repeat FNA, molecular testing, or thyroid lobectomy.
  • Category IV nodules may be assessed as follicular neoplasm or as suspicious for follicular neoplasm. Molecular testing or lobectomy are the adult management options.
  • Category V describes nodules suspicious for malignancy. Either lobectomy or total thyroidectomy are options for adult management.
  • Category VI is reserved for clearly malignant nodules. Again, lobectomy or total thyroidectomy are the adult management options.

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