Multifocality related factors in papillary thyroid carcinoma.

Background: Papillary thyroid carcinoma (PTC) is the main type of the well-differentiated thyroid carcinomas. Multifocality is regarded as a poor prognostic factor for PTC.

Methods: Documents of 777 patients who underwent thyroidectomy were reviewed retrospectively. A total of 305 PTC patients were included. Patients with multifocal PTC were included in Group 1, and patients with unifocal PTC were included in Group 2.

Results: There were 165 patients (54.0%) in Group 1 and 140 patients (46%) in Group 2. The pathological mixed variant of PTC was significantly higher in Group 1 (p = 0,005). Lymph node metastasis (LNM) was detected at 9.6% and 3.5% in Group 1 and Group 2, respectively (p = 0,028). Micro PTC rates were 28.4% and 40.7% in Group 1 and Group 2, respectively (p = 0,017). Tumor size and pathologically mixed-type and fine-needle aspiration biopsy (FNAB) results were significantly different between multifocal and unifocal Micro PTC (p < 0.05).

Conclusions: Multifocality is more frequent in patients with tumors ≥1 cm and mixed-type tumors. LNM is found more often in multifocal tumors. The presence of micropapillary tumors can be predicted preoperatively by ultrasound-guided FNAB. Mixed-type pathology is also a predictive factor for multifocality.