Distant Soft-tissue Metastasis of Follicular Thyroid Carcinoma: A Series of Three Cases

Follicular Thyroid Carcinoma (FTC) accounts for 25-40% of thyroid cancers and is more common in women. The peak incidence is between 40 and 60 years of age. The extent of invasion and stage at presentation are the main prognostic factors of FTC. Invasive carcinoma often presents with systemic metastases to the lungs, skeleton, and brain, with other less common sites including the breast, muscle, and skin. Soft-tissue metastasis is a rare presentation; only limited data are available in the literature. Here, we report three adult females with soft-tissue metastasis of FTC in the gluteal, facial, and inguinal regions. All cases had a prior diagnosis of FTC and had undergone thyroidectomy. During postoperative evaluation, they presented with soft-tissue swelling. All cases presented six months to one year after successful thyroidectomy. In two cases, metastasis occurred in distant soft-tissue sites such as the thigh and gluteal region, whereas in one case the face (a closer region) was involved. The cases were provisionally diagnosed by Fine Needle Aspiration Cytology (FNAC), followed by tru-cut biopsy and Histopathological Examination (HPE). The diagnosis was confirmed by immunohistochemical staining. As metastasis of FTC to soft-tissue is unusual, postoperative follow-up of all FTC patients is mandatory for early detection and treatment.