Endocrine Abstracts

JOINT3705

Introduction: Papillary thyroid cancer accounts for over 85% of thyroid cancers. About 3.9% of these cancers develop bone metastases. Humeral metastases are rare and exceptional.

Observation: A 57-year-old female patient underwent total thyroidectomy in 2022. Histopathological examination revealed a 9cm, poorly defined, left toto-lobar papillary carcinoma with vascular emboli and no capsular effraction. Post operative iratherapy at a dose of 100mCi was indicated, with a huge cervical residue on whole-body scan. The extension work-up revealed bone metastases at C6 and D1, with pulmonary metastases in the form of scattered pulmonary nodules, the largest of which was 19mm mediobasal on the left and 13mm posterobasal on the right. The patient underwent external radiotherapy (8Gy) for decompressive purposes, followed by sorafenib 800mg/day. Three months later, the patient presented with mechanical pain in the left humerus radiating to the left shoulder. A CT scan showed a heterogeneous hypodense mass measuring 61x56x80mm in the neck and proximal third of the humeral diaphysis, with necrotic aeras containing fluid. Bone scintigraphy confirmed metastatic lesions in the left humerus. The patient benefited from placement of a centromedullary nail with simple postoperative follow-up.

Discussion and conclusion: Bone metastases secondary to thyroid cancer are uncommon, but a rigorous clinical history and careful examination are essential for their early detection. The humerus is one of the extremely rare sites of metastatic spread. Conventional surgical approaches for humeral metastases include the use of centromedullary nails, our patient’s case, plate fixation and augmentation with cement to reconstruct large bone defects.