Multifocal Versus Solitary Papillary Thyroid Carcinoma.

BACKGROUND: Papillary Thyroid Carcinoma (PTC) which accounts for >85 % of all thyroid cancers in iodine-rich areas, appears either as a single tumor or as two or more, neoplastic foci within the thyroid gland (Multifocal PTC). We present the comparative results between solitary and MFC PTC.

MATERIALS AND METHODS: Demographics, tumor characteristics (size, laterality, foci number, histologic subtype) and TNM staging were compared between solitary and MFPTC patients. The presence of lymphocytic or Hashimoto's thyroditis was also recorded.

RESULTS: From January 2008 to December 2012, among 647 PTC patients, 241(37.2 %) had MFPTC 177 females (73.4 %) and 64 males (26.6 %), mean age 48.5 years (range 12-87). Mean number of tumor foci was 3.3 (range 2-26). MFPTC patients presented with more advanced T stage (28.2 vs. 18.7 %, p = 0.01) and more LN metastases (28.6 vs. 15.5 %, p < 0.001). Foci number correlates with male gender and LN metastases (p = 0.014 and p = 0.019, respectively). Central (N1a) or lateral (N1b) LN involvement correlates strongly with male gender (p  = 0.024) and younger age (p < 0.001). The follicular variant was the next most frequent histologic subtype associated with extremely rare LN metastases.

CONCLUSION: MFPTC comprises a more aggressive form of papillary thyroid cancer since it is associated with more frequent N1a/ N1b disease and occurs more frequently in T3/T4 patients. MFPTC foci number correlates with male gender and LN metastases.