Clinical, histopathological, and molecular characteristics of papillary thyroid microcarcinoma.
BACKGROUND
Papillary thyroid microcarcinoma (PTMC) detection has been increasing explosively with the recent improvement and application of new diagnostic tools. However, the associations between clinical, histopathological, and molecular findings are often not fully evaluated in reaching a decision for the treatment of PTMC.


OBJECTIVE
To retrospectively evaluate the patients diagnosed with PTMC in terms of the clinical and histopathological features and the immunohistochemical findings of specific molecular markers, and thereby provide an association with the disease prognosis for the Korean patients.


METHODS
We have reviewed the clinical records of patients who underwent surgery for thyroid cancer (during January 2000 to August 2006 interval) at St. Mary's Hospital, Seoul, Korea. The clinical and histopathological characteristics of 217 PTMCs were evaluated cross-sectionally after surgery, and immunohistochemical staining of p53, epidermal growth factor receptor (EGFR), Ki-67, and cyclooxygenase-2 (COX-2) for 87 isolated specimens was performed.


RESULTS
The proportions of extrathyroid extension, lymphatic invasion, and lymph node metastasis cited were 31.9%, 19.2%, and 17.8%, respectively. However, distant metastasis was not noted. Fifty-three (27.1%) patients had multiplicity, and 39 patients (20.0%) had bilateral disease. A primary tumor larger than 5 mm was significantly associated with extrathyroid extension, lymphatic invasion, and lymph node metastasis. The absence of EGFR expression shown by immunohistochemical analysis was closely correlated with extrathyroid extension and lymph node metastasis, while the absence of COX-2 expression was associated with multiplicity and bilaterality.


CONCLUSIONS
Many patients with PTMC had clinical and histopathological poor prognostic factors. The expression of molecular markers, such as EGFR and COX-2, may have a role in the prognosis of PTMC. When considering all of the prognostic factors, a more tailored management approach appears to be necessary for patients with PTMC.
Lim
Dong-Jun
DJ
Department of Internal Medicine, College of Medicine, The Catholic University of Korea, Seoul, Korea.
Baek
Ki-Hyun
KH
Lee
Youn-Soo
YS
Park
Woo-Chan
WC
Kim
Mee-Kyoung
MK
Kang
Moo-Il
MI
Jeon
Hae-Myung
HM
Lee
Jong-Min
JM
Yun-Cha
Bong
B
Lee
Kwang-Woo
KW
Son
Ho-Young
HY
Kang
Sung-Koo
SK
D000328:Adult; D000368:Aged; D002291:Carcinoma, Papillary / Q000473:pathology* / Q000503:physiopathology*; D051546:Cyclooxygenase 2 / Q000032:analysis; D066246:ErbB Receptors / Q000032:analysis; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D007457:Iodine Radioisotopes / Q000627:therapeutic use; D019394:Ki-67 Antigen / Q000032:analysis; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D013964:Thyroid Neoplasms / Q000473:pathology* / Q000503:physiopathology*; D013965:Thyroidectomy; D016159:Tumor Suppressor Protein p53 / Q000032:analysis
D007457:Iodine Radioisotopes; D019394:Ki-67 Antigen; D016159:Tumor Suppressor Protein p53; D051546:Cyclooxygenase 2; D066246:ErbB Receptors