Endocrine Abstracts

Objective: Papillary thyroid microcarcinoma (PTM) is a malignant thyroid tumour with potential multifocality and diameter ≤1 cm. Usually is found like incidentaloma, and the epidemiology is not clearly established. We have analysed their epidemiologic in La Palma Island at last 10 years.

Patients and methods: We collected all cases of PTM diagnosed in 345 consecutive thyroid surgeries performed for whichever benign thyroid disease (thyrogloss duct cyst – TDC – included), at the last 10 years (from 2000 to 2009). Prevalence and incidence were expressed as % and % per year, respectively; and the mean values like mean±S.D. To compare variables, Student’s t and χ²-tests were used.

Results: Thyroidectomy was performed in 297 females and 48 males with mean age 49.6±15.3 years (4–85). We found 53 cases of PTM (8 M, 45 F) with mean age 50.9±11.9 years (25–78). Just one was diagnosed before thyroidectomy (PTM in a TDC). The PTM prevalence was higher in euthyroid multinodular goitre – MNG – (20.1%) followed by thyroid solitary nodule (18.2%), toxic adenoma and hypofunctioning MNG (14.3%), Graves’ disease (10%), toxic MNG (9%) and TDC (3.8%). The mean tumour size was 3.4±2.9 mm. Multifocality was observed in 13.2%. TNM and staging classification according 2006 European Thyroid Cancer Consensus was T_1aN₀M₀ and stage I, respectively, in all subjects. Total prevalence was 15.4% without differences respect to sex (16.7% in M, 15.2% in F). The annual incidence oscilated between 3.3 and 20.8%, showing a striking and progressive increase at the last years (9.8% in 2000–2004 vs 18% in 2005–2009, P=0.048).

Conclusions: PTM is more frequent in nodular thyroid disease. The prognosis is excellent in relation to the TNM and staging classification. The prevalence is high, as well as its multifocality, increasing at the last years. It depends on the extended indications for total thyroidectomy for benign diseases, on progress in the field of diagnostic procedures, and on the pathology examination.