SUN-482 A Very Rare Case of Thyroid Cancer

Abstract

Background: Cribriform-Morular variant of Papillary Thyroid Cancer (PTC-CMV) is an exceedingly rare subtype of thyroid cancer that predominantly affects younger females. As the name implies, it is a papillary thyroid carcinoma with predominantly cribriform and morular pattern of carcinoma cells on cytopathology. While completion thyroidectomy is usually recommended for larger and higher-risk Papillary Thyroid Cancer (PTC), surveillance may be acceptable with PTC-CMV, which tends to be a less aggressive malignancy. Clinical Case: A 46-year-old Guyanese woman presented with a three week history of an enlarging right-sided neck mass associated with a globus sensation while swallowing food. She denied any history of radiation exposure. Her exam findings were positive for a tender, right-sided neck mass. CT neck without contrast revealed a 4.1 x 4.0 x 5.9cm heterogeneous mass within the right thyroid lobe causing mild tracheal deviation to the left. Ultrasound of thyroid gland showed a solid heterogeneous hypoechoic 4.22 x 2.39 x 2.46cm right lobe nodule with no microcalcifications, border irregularity or taller-than-wider morphology. Fine Needle Aspiration of the nodule came back as Atypia of Undetermined Significance. The patient then underwent a core needle biopsy. The resultant pathology was negative for thyroid carcinoma or medullary thyroid carcinoma but was suggestive of a bronchial cleft cyst versus bronchogenic cyst with atypical glandular proliferation. She subsequently underwent a right hemithyroidectomy which revealed a final pathological diagnosis of a 3.5cm PTC-CMV. Such pathology warranted the patient to undergo a colonoscopy which was negative for Familial Adenomatous Polyposis (FAP). Given her negative GI workup and non-contributory family history for colonic polyposis or carcinoma the decision was made to continue surveillance rather than performing completion thyroidectomy as the disease was presumed to be sporadic. Discussion: PTC-CMV accounts for 0.2% of all PTC. It is associated with FAP in more than 50% of cases but can also occur sporadically. This subtype of PTC generally follows a less aggressive course. Review of current literature revealed several case series of CMV-PTC patients. In the largest one, 32 cases were observed over a 19 year period and only two out of twelve patients with FAP-associated PTC-CMV initially treated with hemithyroidectomy developed recurrence to the contralateral lobe. Interestingly, none of the remaining patients with the sporadic type developed recurrence suggesting that completion thyroidectomy may not be mandatory in this group. It is, therefore, critical to identify these patients and screen them with a colonoscopy to avoid the potentially unnecessary resection of the contralateral lobe and the consequent need for thyroid hormone replacement.