Occult papillary thyroid carcinoma: diagnostic and clinical implications in the era of routine ultrasonography

Abstract
Background  Papillary carcinoma with clinically apparent node metastasis but lacking a primary carcinoma lesion in the thyroid is designated
as occult papillary carcinoma. In the era of routine ultrasonographic examination, occult papillary carcinoma is defined as
papillary carcinoma with clinically apparent node metastasis but showing a primary lesion that is microscopic or overlooked
by ultrasonography. In this study we investigated the prevalence and clinicopathologic features, including prognosis, of occult
papillary carcinoma.

Methods  This is a retrospective series study of all patients with occult papillary thyroid carcinoma who underwent initial surgery
at a single institution over 14 years.

Results  Between 1990 and 2004, 5400 patients underwent surgery for papillary thyroid carcinoma at Kuma Hospital, Japan. Seventeen
(0.3%) were regarded as having occult papillary carcinoma and were enrolled in the study. Clinically apparent node metastasis
was detected in the lateral compartment in 16 patients and in the mediastinal compartment in 1 patient. Multiple metastatic
nodes were detected in 5 patients (29%). Primary lesions of papillary carcinoma were intraoperatively detected in 3 of 14
patients (21%) who underwent thyroidectomy, but there were no apparent carcinoma lesions in the thyroid in 5 patients (36%),
even on pathologic examination. Six patients (35%) showed extranodal tumor extension to adjacent organs and two of these patients
showed recurrence. None of the patients showed distant metastasis or died of carcinoma over the study period.

Conclusions  Patients with occult papillary thyroid carcinoma were found to have a favorable overall prognosis. However, occult papillary
carcinoma is automatically classified as N1b in the UICC classification, and in our series it is also likely to show other
aggressive clinicopathologic features. In particular, extranodal tumor extension portends a worse prognosis for patients with
occult papillary carcinoma. Therefore, careful total thyroidectomy with lymph node dissection is recommended except for elderly
or high-risk patients.

Content Type Journal ArticleDOI 10.1007/s00268-008-9614-9Authors
Yasuhiro Ito, Kuma Hospital Department of Surgery 8-2-35, Shimoyamate-dori, Chuo-ku Kobe City 650-0011 JapanMitsuyoshi Hirokawa, Kuma Hospital Department of Pathology 8-2-35, Shimoyamate-dori, Chuo-ku Kobe City 650-0011 JapanMitsuhiro Fukushima, Kuma Hospital Department of Surgery 8-2-35, Shimoyamate-dori, Chuo-ku Kobe City 650-0011 JapanHiroyuki Inoue, Kuma Hospital Department of Surgery 8-2-35, Shimoyamate-dori, Chuo-ku Kobe City 650-0011 JapanTomonori Yabuta, Kuma Hospital Department of Surgery 8-2-35, Shimoyamate-dori, Chuo-ku Kobe City 650-0011 JapanTakashi Uruno, Kuma Hospital Department of Surgery 8-2-35, Shimoyamate-dori, Chuo-ku Kobe City 650-0011 JapanMinoru Kihara, Kuma Hospital Department of Surgery 8-2-35, Shimoyamate-dori, Chuo-ku Kobe City 650-0011 JapanTakuya Higashiyama, Kuma Hospital Department of Surgery 8-2-35, Shimoyamate-dori, Chuo-ku Kobe City 650-0011 JapanYuuki Takamura, Kuma Hospital Department of Surgery 8-2-35, Shimoyamate-dori, Chuo-ku Kobe City 650-0011 JapanAkihiro Miya, Kuma Hospital Department of Surgery 8-2-35, Shimoyamate-dori, Chuo-ku Kobe City 650-0011 JapanKaoru Kobayashi, Kuma Hospital Department of Surgery 8-2-35, Shimoyamate-dori, Chuo-ku Kobe City 650-0011 JapanFumio Matsuzuka, Kuma Hospital Department of Surgery 8-2-35, Shimoyamate-dori, Chuo-ku Kobe City 650-0011 JapanAkira Miyauchi, Kuma Hospital Department of Surgery 8-2-35, Shimoyamate-dori, Chuo-ku Kobe City 650-0011 Japan

Journal World Journal of SurgeryOnline ISSN 1432-2323Print ISSN 0364-2313 (Source: World Journal of Surgery)