title: Clinicopathological analysis of small-sized thymoma with podoplanin and Ki 67 expression analysis.
abstract: Thymoma is the most common tumor of the anterior mediastinum for which surgical resection is currently the primary form of treatment. An increase in the incidence of a small-sized (≤3 cm) thymoma (SST) has recently been noted. Clinicopathological factors and prognosis of SST have not been reported previously. In this study, the clinicopathological data of 21 SST patients were reviewed and podoplanin and Ki67 immunohistochemistry were assessed to determine the biological behavior of SSTs. Pathological diagnosis of SSTs revealed the following types: A (n=1), AB (n=8), B1 (n=5), B2 (n=6) and B3 (n=1). The Masaoka-Koga stages of 21 thymoma patients were I (n=16), II (n=3), III (n=1) and IVb (n=1). In the case of the stage IVb thymoma, phrenic nerve, mediastinal pleura invasion and anterior mediastinal lymph node metastasis were observed. The Ki67 labeling index of this stage IVb was found to be 3.2. This case was also positive for podoplanin and was one of the only 2 cases that were positive for podoplanin. This patient succumbed to thymoma. Advanced stage thymomas are possibly included in SSTs although the majority of SSTs are classified into early stages of disease. Findings of this study suggest that podoplanin analyzed by immunohistochemistry may be useful to determine the malignant behavior of SSTs.
authors.affiliation: Department of Oncology, Immunology and Surgery, Nagoya City University Graduate School of Medical Sciences, Nagoya;
authors.forename: Keisuke
authors.initials: K
authors.lastname: Yokota
authors.affiliation: Department of Pathology, Kasugai Municipal Hospital, Kasugai;
authors.forename: Hisashi
authors.initials: H
authors.lastname: Tateyama
authors.affiliation: Department of Oncology, Immunology and Surgery, Nagoya City University Graduate School of Medical Sciences, Nagoya;
authors.forename: Motoki
authors.initials: M
authors.lastname: Yano
authors.affiliation: Department of Oncology, Immunology and Surgery, Nagoya City University Graduate School of Medical Sciences, Nagoya;
authors.forename: Satoru
authors.initials: S
authors.lastname: Moriyama
authors.affiliation: Department of Oncology, Immunology and Surgery, Nagoya City University Graduate School of Medical Sciences, Nagoya;
authors.forename: Yu
authors.initials: Y
authors.lastname: Hikosaka
authors.affiliation: Department of Oncology, Immunology and Surgery, Nagoya City University Graduate School of Medical Sciences, Nagoya;
authors.forename: Katsuhiro
authors.initials: K
authors.lastname: Okuda
authors.affiliation: Department of Oncology, Immunology and Surgery, Nagoya City University Graduate School of Medical Sciences, Nagoya;
authors.forename: Masayuki
authors.initials: M
authors.lastname: Shitara
authors.affiliation: Department of General Thoracic Surgery, Osaka University Graduate School of Medicine, Osaka;
authors.forename: Meinoshin
authors.initials: M
authors.lastname: Okumura
authors.affiliation: Division of Thoracic Surgery, Nagoya University Graduate School of Medicine, Nagoya, Japan.
authors.forename: Kohei
authors.initials: K
authors.lastname: Yokoi
authors.affiliation: Department of Oncology, Immunology and Surgery, Nagoya City University Graduate School of Medical Sciences, Nagoya;
authors.forename: Yoshitaka
authors.initials: Y
authors.lastname: Fujii
keywords: Ki67; podoplanin; small-sized; thymoma