title: Total surface area is useful for differentiating between aggressive and favorable multifocal papillary thyroid carcinomas.
abstract: OBJECTIVE
  The purpose of the present study was to identify more useful parameters for predicting behaviors of multifocal papillary thyroid carcinoma (PTC).
  
  
  METHODS
  We investigated dominant tumor diameter (TD), total tumor diameter (TTD), and total surface area (TSA) in tumors from 588 patients and evaluated their usefulness as parameters for assessment of tumor behaviors in multifocal PTCs.
  
  
  RESULTS
  In 588 PTCs, tumor multifocality was found in 179 PTCs (30.4%). Multifocal tumors were significantly associated with extrathyroidal extension, lymph node metastasis, and higher tumor stage grouping (p<0.001, p<0.001, and p<0.001, respectively). The rates of nodal metastasis increased with greater TSA and TTD in PTCs. Multifocal papillary thyroid microcarcinomas (mPMCs) with TSA >3.14 cm² had higher rates of nodal metastasis than mPMCs with TSA ≤3.14 cm² (p=0.038); however, there was no significant difference between mPMCs with TTD >1.0 cm and with TTD ≤1.0 cm (p=0.325). In addition, nodal metastasis was more frequent in mPMCs with TSA >3.14 cm² than in unifocal papillary thyroid microcarcinomas (uPMCs) (TD ≤1.0 cm) (p=0.002), but not overt unifocal PTCs (TD >1.0 cm) (p=0.244).
  
  
  CONCLUSIONS
  Our results suggest that mPMCs with TSA >3.14 cm² show more aggressive behavior than uPMCs and mPMCs with TSA ≤3.14 cm². TSA could be useful in distinguishing aggressive mPMCs from favorable cases.
authors: Department of Pathology, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul, Korea.
authors: Jung-Soo
authors: JS
authors: Pyo
authors: Department of Pathology, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul, Korea. jhpath.sohn@samsung.com.
authors: Jin Hee
authors: JH
authors: Sohn
authors: Department of Pathology, Sanggye Paik Hospital, Inje University College of Medicine, Seoul, Korea.
authors: Guhyun
authors: G
authors: Kang
authors: Department of Pathology, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul, Korea.
authors: Dong-Hoon
authors: DH
authors: Kim
authors: Department of Surgery, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul, Korea.
authors: Jisup
authors: J
authors: Yun
mesh_terms: D000328:Adult; D000368:Aged; D002277:Carcinoma / Q000473:pathology* / Q000601:surgery; D002291:Carcinoma, Papillary / Q000473:pathology* / Q000601:surgery; D005260:Female; D006801:Humans; D008198:Lymph Nodes / Q000473:pathology* / Q000601:surgery; D008207:Lymphatic Metastasis / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D011237:Predictive Value of Tests; D011379:Prognosis; D000077273:Thyroid Cancer, Papillary; D013964:Thyroid Neoplasms / Q000473:pathology* / Q000601:surgery; D013965:Thyroidectomy
keywords: Papillary thyroid carcinoma; lymph node metastasis; multifocal; total surface area