SAT534 A Rare Case of Poorly Differentiated Thyroid Cancer With Extraordinary Limitations to Treatment

Disclosure: N. Shahid: None. L. Rudman: None. H. Maldonado Rivera: None. J. Chambi-Torres: None. J.A. Gonzalez: None. S. Valepu: None. A. Barco: None. N.H. Shaaban: None. E. Angueira: None. Background: Poorly differentiated thyroid cancer (PDTC) is a rare and aggressive form of follicular epithelial cell derived thyroid carcinoma, representing 3-5% of all thyroid cancers. As a subtype, PDTC is in a category that is between well differentiated thyrocyte malignancies and undifferentiated (anaplastic) thyroid carcinomas. Current guidelines for treatment of PDTC are not well defined. Case presentation: A 56-year-old male with a history of PDTC was admitted to the hospital directly from a correctional facility due to concern for metastasis. Patient had a total thyroidectomy performed just two months ago that revealed PDTC on surgical pathology. Recommendations at that time were to complete a full body PET-CT and follow up with radiation oncology for radiation and chemotherapy. Patient was also discharged on Synthroid 175 mcg daily for TSH suppression. However, the patient did not have any follow up appointments scheduled while at the facility. PET-CT showed stable FDG avid 2.4 cm lower right neck mass and 2 cm focus of mildly increased activity in the right lobe of the liver. On admission, a triple phase MRI liver protocol was ordered and showed a 15 mm hepatic lesion that was arterially enhancing with persistent enhancement in venous and delayed phase without dropping signal on T2 fat and additional hyperintensity on T2. Bilateral 1.7 cm adrenal nodule was also identified with relative hypointensity on T2. FNA of right neck mass was performed but did not yield sufficient tissue for pathology. Subsequent right neck exploration and skin biopsies were obtained and revealed benign fibroadipose tissue with focal fat necrosis in the thyroid and lobular capillary hemangioma in right back, left chest, and right abdomen. Patient’s status as an inmate continued to delay radiation and chemotherapy for PDTC with possible metastasis. The decision was made with the hematology/oncology inpatient consult team to perform RAI treatment with 138 mCI of I-131. Synthroid was held in anticipation of the RAI and whole body scan was ordered for 1 week after administration of I-131. Post ablation whole body scan showed intense radiotracer uptake over the region of the left and right thyroid glands and normal uptake in the stomach, small bowel, and urinary bladder. No other areas of radiotracer uptake were found. Conclusion: Diagnosis and treatment of PDTC is challenging and the social constraints as an inmate make it even more difficult to initiate appropriate therapy with radiation oncology follow up. Our case illustrates the implications of RAI ablation after total thyroidectomy in staging and therapy of PDTC. Given the intermediate histologic characteristics of PDTC, further investigation is required in the setting of metastasis and exploration of the benefits of early aggressive therapy, such as external beam radiotherapy. Presentation Date: Saturday, June 17, 2023