Use of molecular testing results to analyze the overuse of atypia of undetermined significance in thyroid cytology.

INTRODUCTION: The suggested atypia of undetermined significance (AUS) rate for thyroid fine-needle aspiration biopsies is 10% or less. Prompted by a high institutional AUS rate, we examined using molecular testing results (MTR) as a potential quality metric tool to reduce the AUS rate. We correlated MTR with AUS cytologic findings, surgical pathology follow-up, and individual pathologist AUS rates. MATERIALS AND METHODS: Demographic data, cytologic diagnoses, MTR, and surgical pathology diagnoses were retrospectively obtained. MTR were classified as either positive or negative. AUS rates and MTR proportions were compared among pathologists. The cytomorphologic features of 143 AUS cases were assessed and correlated with MTR. RESULTS: Between 2017 and 2022, 710 of 3247 thyroid fine-needle aspirations were classified as AUS, with a yearly average rate of 22% (range = 19%-26%). AUS cases included: 331 (47%) with architectural atypia; 204 (29%) with oncocytic (Hürthle cell) atypia; 99 (14%) with combined architectural and cytologic atypia; and 76 (10%) with isolated cytologic atypia. Most AUS cases with molecular testing had negative MTR (360/492, 73%). AUS with cytologic atypia had higher positive MTR risk (logarithm of odds ratio = 1.27, 95% credible interval [0.5-2.04], P = 0.001). The average positive MTR rate by pathologist was 21.5% (range 0%-35%); higher positive MTR rates had better correlation with subsequent neoplastic/malignant histologic diagnoses. The MTR sensitivity for malignant disease was 89% and the negative predictive value was 91%. CONCLUSIONS: MTR analysis reveals the importance of cytologic atypia as a determinant of malignancy risk in AUS cases. Periodic analysis of MTR data alongside individual pathologist AUS rates can help refine diagnostic criteria and potentially reduce AUS overuse.

Invaluable role of histopathology in the diagnosis of cutaneous leiomyosarcoma in insulin injection site reaction.

Soft tissue sarcomas (STSs) are rare and may often be misdiagnosed, resulting in delays in treatment. A 67-year-old cisgender woman with type 2 diabetes mellitus and obesity presented to her primary care physician with a mass on her left proximal arm. The clinical opinion of the attending physician was that of an insulin injection site reaction. After further evaluation from the physician, the patient was diagnosed with a lipoma without confirmatory histology. The patient continued to present with an enlarging mass, decline in health status and continued with local wound care. The patient underwent a confirmatory biopsy following which, the patient was diagnosed with leiomyosarcoma. This case report highlights the case of a person with a low or moderate income with a self-reported low health literacy living in a rural community and how STS may be misdiagnosed in medically underserved. The patient's primary or oncology care team are not involved in the production or review of this case report.