[Papillary microcarcinoma of the thyroid]

Treatment of thyroid differentiated carcinoma is controversial. In case of papillary microcarcinoma a low malignancy is usually considered and a limited surgical excision is currently used. We describe 49 cases with papillary tumor < 1 cm. Their high frequency (51% of all differentiated carcinoma discovered in the same period), current mode of their diagnosis (incidental histological findings: N = 48), and constant tumoral situation in extra nodular parenchyma are emphasised. In spite of median tumor size < 2 mm, 8% had extra thyroidal tumoral extent at diagnosis (node metastasis: N = 3; bone: N = 1). In one case with multifocal lesions in both lobes, an unilateral thyroidectomy would have missed contralateral periglandular metastatic nodes. Diagnosis of the case with asymptomatic bone metastasis was clearly attributable to radioiodine therapeutic use. These results suggest an heterogeneous prognosis of papillary microcarcinoma, with some cases requiring total bilateral thyroidectomy and radioiodine remnants ablation (e.g. Tumors invading peripheral thyroid tissue that seem at higher risk of extra glandular extension).