Metastatic Follicular Thyroid Carcinoma Diagnosed by Fine Needle Aspiration Cytology

BACKGROUND: Follicular thyroid carcinomas (FTCs) usually have a benign clinical course, with an excellent long-term prognosis and a propensity for vascular invasion. The most common sites of metastases are lung and bone. Only a few reports are available on fine needle aspiration biopsy findings from metastatic lesions of FTC. CASES: A 68-year-old man presented with a thyroid mass and skin nodule on the scalp. Skin nodule aspiration revealed metastatic FTC. A 52-year-old woman and 60-year-old man were investigated for chronic anemia. As part of the routine investigation, bone marrow aspiration and biopsy were performed from the posterior iliac crest and diagnosed as metastatic FTC. Further questioning revealed that the patients had undergone thyroidectomy 10 and 13 years earlier. The aspiration material in all 3 cases revealed epithelial cell clusters with marginal (fire-flare) vacuoles. CONCLUSION: Cytologic diagnosis of metastatic FTC has been reported rarely. Marginal (fire-flare) vacuoles aid in making the diagnosis of metastatic FTC.