Solitary Metastasis to Humerus: Unusual Presentation of Follicular Thyroid Carcinoma Diagnosed by Fine Needle Aspiration Cytology

Follicular carcinoma of thyroid metastasizes to bone, clinically presenting as a large tissue swelling only, with silent primary is very rare one and is reported to be 4% of all thyroid cancers.Appendicular skeleton like humerus is a rare site of skeletal metastasis in follicular carcinoma as compared to axial skeletons.Here, we report such an unusual case of a 70 year old woman presenting with a huge swelling over left upper arm mimicking primary bone tumor both clinically and radiologically.It was diagnosed as metastatic follicular thyroid carcinoma by fine needle aspiration cytology (FNAC).Later follicular carcinoma was detected in thyroid by cytology and confirmed by histology.Patient was treated by total thyroidectomy with iodine therapy and external beam radiotherapy to bone.FNAC is a cheap, rapid, non-invasive and accurate diagnostic modality which can help in early diagnosis of such lesions helping in proper management and better prognosis.