Objective: Papillary thyroid microcarcinoma (PTM) is a malignant thyroid tumor with potential multifocality and diameter ≤1 cm. This carcinoma has been discovered more frequently like incidentaloma, and the epidemiology is not clearly established. We have analysed epidemiologic and clinical characteristics in La Palma Island.
Patients and methods: We collected all cases of PTM diagnosed in 188 consecutive thyroidectomies performed for whichever cause, admitted from 2000 to 2007. We reported the pre-surgical diagnosis, sex, age at thyroidectomy, thyroid function, thyroid autoimmunity, tumor size, multifocality, tumor extension, and cytology and pathology results. The prevalence and incidence were expressed as percentage and percentage per year, respectively. The mean values were expressed as media±S.D.
Results: Thyroidectomy was performed in 166 females and 22 males. The mean age was 50.6±14.8 years (1385). We found 38 cases of PTM (5 M, 33 F). The mean age was 50.7±13.1 years (2578). Only one case was diagnosed before thyroidectomy. The PTM prevalence was higher in thyroid solitary nodule (40%), followed by euthyroid multinodular goitre MNG- (28%), hypofunctioning MNG (20%), thyrogloss cyst (20%), Graves-Bassedow disease (7.7%) and toxic MNG (7.3%). The mean tumor size was 0.3±0.2 mm (0.110). Multifocality was observed in 29.6%. One case (2.6%) has extrathyroid extension (adenopathy). Euthyroidism, hypothyroidism and hyperthyroidism were presents in 81.6%, 13.2% and 5.3%, respectively. Thyroid autoimmunity in 7.9%. The prevalence was 20.3 without sex differences (22.7 M, 20 F). The annual incidence oscilated among 2.6 and 34.2, showing a striking and progressive increase at the last years.
Conclusions: PTM is more frequent in nodular thyroid disease. Its prevalence is high, as well as its multifocality (almost 1/3), 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.