Thyroid Metastasis Revealing Prostatic Adenocarcinoma

Introduction: Metastasis to the thyroid gland is rarely encountered and usually detected after the diagnosis of the primary tumor. The most common sites of primary are breast, kidney, and lung. Prostate has been rarely reported as primary site. Here is reported a case of thyroid metastasis revealing prostate adenocarcinoma. Case summary: A 59-year-old man was admitted for pulmonary embolism. CT scan showed a hypertrophy of left thyroid lobe, and ultrasonography of the neck revealed cervical nodes. Thyroid function tests were within normal limits. Total thyroidectomy associated to cervical nodes dissection was done. There was no postoperative complication. Histopathological examination of the surgical specimen concluded to a papillary carcinoma. Then, immunohistochemistry examination revealed prostatic metastatic adenocarcinoma to lymph node and thyroid gland. The patient was treated by androgen deprivation therapy. After thirty three months of follow-up, he is still in good condition with stable disease. Conclusion: This case suggests thyroid cancer might be metastasis, and more frequent than known. Surgical specimen of thyroidectomy requires further histological examination such as immunohistochemistry to document primary tumor. Prostate is one of the primary, despite not the most common.