Endocrine Abstracts

Introduction: Cutaneous metastization of differentiated thyroid carcinomas is a rare event.

Clinical case: MMS, a 69-year-old male was submitted to left hemithyroidectomy+isthmectomy on May 2006 after FNA of a left node revealed follicular tumor. Histology showed Hurthle cell adenoma. The patient maintained irregular follow-up by endocrinologist. In October 2011 he referred the appearance of small bilateral cervical skin nodules. Physical exam showed three subcutaneous, 4 mm diameter, nodules, and a 7 mm diameter lymph node. Ultrasonnography of thyroid and cervical soft tissues was reccomended. The patient returned to the endocrinologist in October 2012, referring increase in size of the cervical nodules, which was confirmed by physical examination. A FNA was requested, having revealed ‘cytological and immunohistochemical findings compatible with the diagnosis of Hurthle cell follicular tumor. Clinical and imageological correlation was suggested to differentiate between lymoh node metastasis of Hurthle cell follicular tumor or tumor recurrence. Paraffin blocks used in 2006 were recovered and examined by a different pathologist. Histology showed, in addition to a papillary carcinoma, histological findings compatible with thyroid oxiphyl (Hurthle cell) neoplasm. On the three examined blocks no unequivocal images of capsule or vascular invasion were observed, turning it impossible to differentiate between adenoma and Hurthle cell carcinoma.

Thyroidectomy totalization and extenal nodules removal were performed. Histologycal exam revealed ‘oncocytic cell carcinoma, occupying extrathyroidal tissues with venous and lymphatic invasion. In the nodules an identical neoplasm is observed, that invades skeletal muscle. There is TTF1 and thyroglobulin expression. In conclusion: extensively invasive oncocytic cell (follicular) carcinoma’.

This clinical case constitutes an uncommon example of cutaneous metastization of a differentiated thyroid carcinoma and highlights the importance of a correct differential diagnosis between Hurthle cell adenoma and carcinoma.