Subcutaneous implantation of thyroid carcinoma and benign tissue after thyroidectomy: report on two cases and review of the current literature.

[BACKGROUND] Subcutaneous implantation of thyroid tissue after thyroidectomy is a rare occurrence involving both benign and malignant thyroid tissue. Clinically, subcutaneous implantation of thyroid tissue can be challenging to diagnose. We present two cases of subcutaneous implantation of thyroid tissue following thyroidectomy and discuss the differential diagnosis, clinicopathological characteristics, and the possible mechanism of implantation.

[CASE DESCRIPTION] A 35-year-old woman (age in 2009) who underwent total thyroidectomy in 2009 whose histopathological examination revealed a nodular hyperplasia and lymphocytic thyroiditis complained of palpable mass in her neck 10 years after operation and underwent excision. Follicular adenoma was confirmed in histopathological results. A 58-year-old woman (age in 2010) who underwent lobectomy in 2010 for nodular hyperplasia had a 6 cm sized huge mass in her anterior neck 9 years after operation. Anterior neck mass excision was done and poorly differentiated carcinoma was confirmed in histopathological results. The patient showed no sign of recurrence after 3 years follow-up.

[CONCLUSIONS] Subcutaneous implantation of benign thyroid tissue or thyroid cancer can occur after thyroidectomy. Minimizing the likelihood of subcutaneous implantation requires careful consideration of various factors at every stage of the surgical procedure. Surgeons should be aware of this potential long-term complication that can occur in both conventional thyroidectomy and remote access surgery, effectively communicate and provide appropriate guidance to their patients, and try to avoid seeding of both malignant and benign thyroid tissue.