Metastatic thyroid follicular carcinoma presenting as pathological left clavicle fracture: An unusual skeletal metastasis at the time of diagnosis.

ABSTRACT

INTRODUCTION: Thyroid carcinoma is the most common endocrine malignancy, accounting for 3 % of recent malignancies in world wide. Differentiated thyroid carcinoma constitutes 90 % thyroid malignancies, within that follicular type constitutes 10-15 %. CLINICAL PRESENTATION A 55-year-old female presented with left-sided neck pain and swelling over medial end of clavicle, following normal manual work. Physical examination revealed swelling on medial end of left clavicle and palpable nodule in left thyroid lobe. Imaging studies showed two nodules in both thyroid lobes with left level IV lymphadenopathy and osteolytic lesion with pathological fracture in medial end of clavicle. Histopathological evaluation confirmed well-differentiated follicular thyroid carcinoma with clavicular metastasis. The patient underwent total thyroidectomy, followed by radioiodine therapy for medial end of left clavicle. DISCUSSION: Follicular thyroid carcinoma (FTC) is metastasis through the bloodstream, predominantly to flat bones and upper end of long bones, but clavicular deposits are very rarely reported. FNAC only diagnosed the follicular neoplasm. Further tissue evaluation needed to confirm the malignancy. Therefore, hemithyroidectomy of the lesion side is usually carried out for histopathological diagnosis. But in this case, follicular thyroid carcinoma was confirmed through core biopsy from medial end of clavicle, leading to total thyroidectomy and left cervical block dissection, followed by radioiodine therapy for metastatic clavicular involvement. CONCLUSION: Clavicular metastasis of follicular thyroid carcinoma is very rare. Early detection and proper management of suspicious thyroid carcinoma in uncommon skeletal sites, like the clavicle, is crucial for enhancing patient outcomes, despite the rarity of follicular carcinoma metastasis to this area.