Subcutaneous implantation of oncocytic thyroid cell aggregates nine years later from thyroidectomy. A case report.

Introduction and importance: Subcutaneous implantation of thyroid tissue is a rare clinical condition that involves the head and neck region and occurs after surgery, diagnostic procedures or cervical trauma. Case presentation: A 90-year old woman with two skin nodules on her thyroidectomy scar was hospitalized and treated by two surgical excisions. Histologically, these lesions were two aggregates of cutaneous oncocytic thyroid cells. In the patient's clinical history there was a total thyroidectomy for multinodular goiter, performed 9 years previously and at which a well-encapsulated subcapsular oncocytic adenoma of the left lobe was also incidentally discovered. At 12 months of follow-up, the patient is showed well and her wounds healed. Clinical discussion: Subcutaneous colonization or seeding of thyroid tissue is a rare occurrence reported in the literature for both benign and malignant pathologies; among the malignant ones, the implantation of follicular carcinoma cells is the most frequent. Only in one previous case, to our knowledge, subcutaneous colonization originating from oncocytic thyroid (or Hurthle) cell neoplasms has been described. Conclusion: We report an unusual case of double subcutaneous implantation of oncocytic thyroid cells on the cervical scar of an elderly woman, nine years after total thyroidectomy.