Fine needle aspiration biopsy (FNAB) of the thyroid gland is an important tool for preoperative diagnosis; however, its benefit is limited for follicular lesions. Nucleolar organizer regions (NORs) are ribosomal gene regions that stain with silver (Ag) when they are active. These regions can be used to differentiate neoplastic and non-neoplastic lesions. We used a new AgNOR technique to investigate FNAB of cases diagnosed as follicular adenoma and carcinoma. Fourteen cases of follicular thyroid carcinoma (FTC) and 28 cases of thyroid follicular adenomas (FA) were stained using the silver NOR-associated protein (AgNOR) technique. One hundred nuclei per sample were examined, AgNORs were counted, and the total AgNOR area/nuclear area (TNORa/Na) ratio of each cell was calculated. We found that cases with FTC had significantly higher TNORa/Na than cases of FA. Also, cases with FTC had significantly higher AgNOR counts than cases with FA. AgNOR counting may help discriminate FTC and FA by routine cytopathology before surgery.

Papillary thyroid carcinoma is the most common type of thyroid cancer; metastases occur more frequently in lymph nodes and less often in the lung and bone. Cutaneous metastases from papillary thyroid carcinoma are extremely rare; this is the first case report of the cutaneous metastasis of papillary thyroid carcinoma that developed on the site of incision for thyroidectomy. Most cutaneous metastases in a surgical scar occur as a result of the implantation of tumor cells or direct extension during surgery and usually appear within a year of surgery. 2,7 The present patient is unusual because the interval between thyroidectomy and the development of cutaneous metastasis to the operation scar was five years.Several mechanisms for the occurrence of cutaneous metastasis from internal malignancy have been proposed, including direct extension, hematogenous spread, lymphatic spread, and the implantation of exfoliated tumor cells during surgery. 5 Tumor cell implantation during surgery may be the most likely pathogenesis of metastasis to a surgical scar. However, in the present case, this is less likely because systemic metastases had been detected three years prior to the development of the skin lesion, and the period between the thyroidectomy and the cutaneous metastasis extended to five years. Alternatively, an alteration in local lymphatic drainage in the region of the scar may be the mechanism responsible for tumor cell implantation. Although hematogenous metastasis is possible, why the metastasis occurred in the scar rather than elsewhere remains open to question.Assuming that this was not a random phenomenon, we suggest that there is a predilection for metastasis to occur at an operation scar as a result of an alteration in the microscopic anatomy around the scar, including in the lymphatic channels, or because the local environment of the scar is more susceptible to metastatic tumor cells. It is possible that this may reflect an altered adhesion molecule profile or altered local immunosurveillance mechanisms. In conclusion, although the exact pathogenesis of metastasis remains unknown, we report this case of a papillary thyroid carcinoma metastasis on a thyroidectomy scar on the neck as representing an interesting occurrence.

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