福島医学雑誌 53 巻 3 号　2003

〔原　　著〕

WHO分類からみた胸腺腫の臨床病理学的特徴

藤生　浩一¹⁾，管野　隆三¹⁾，鈴木　　理²⁾，鈴木　弘行¹⁾，塩　　　豊¹⁾，
樋口　光徳¹⁾，大杉　　純¹⁾，大石　明雄³⁾
阿部　正文²⁾，後藤　満一¹⁾

¹⁾福島県立医科大学医学部外科学第一講座　
²⁾同　病理学第一講座
³⁾福島赤十字病院　外科

（受付　2003年6月17日）

Clinicopathological Features of Thymoma Categorized
by WHO Classification

KOICHI FUJIU¹⁾, RYUZO KANNO¹⁾, OSAMU SUZUKI²⁾,
HIROYUKI SUZUKI¹⁾, YUTAKA SHIO¹⁾, MITSUNORI HIGUCHI¹⁾,
JUN OHSUGI¹⁾, AKIO OISHI³⁾, MASAHUMI ABE²⁾
and MITSUKAZU GOTOH¹⁾

¹⁾Department of Surgery I, Fukushima Medical University School of Medicine, Fukushima
²⁾Department of Pathology I, Fukushima Medical University School of Medicine, Fukushima
³⁾Department of Surgery, Fukushima Red Cross Hospital, Fukushima

要旨: 背景: 1999年にWorld Health Organization (WHO) 国際腫瘍組織分類委員会は，胸腺腫瘍に関し国際的に統一した分類を発表した。WHO分類は胸腺腫の臨床病理学的特徴を反映しているかを，自験例をもとに検討した。
対象: 1978年1月〜2003年3月までに教室及び関連施設で手術を行った胸腺腫54例を対象とした。組織分類はWHO分類を，病期分類は正岡分類を用いた。
結果: WHO分類はType A，AB，B1，B2，B3各々8，10，7，6，22例であった。なお1例は放射線照射によりWHO分類不能であった。正岡分類はStage I，II，III各々24，19，11例であった。WHO分類と正岡分類の関係では，Type A，ABではStage IIIの患者を認めず，Type B1，B2ではStage IIIは30% 以下であり，Type B3では22例中8例 (36.4%)がStage IIIであった。
　正岡分類，WHO分類と予後の関係では，WHO分類Type A，ABでは腫瘍死および再発を認めなかったが，Type B1では1名が腫瘍死，1名が再発，Type B2では2名が再発，Type B3では3名が腫瘍死していた。
　胸腺腫の合併症として，重症筋無力症を19例に認め，12例 (63.2%) がType B3であった。一方，赤芽球癆の合併は4例で，1例がType A，2例がType AB，1例がType B1であった。
結論: Type A，ABでは浸潤度が弱く予後良好であった。一方，Type B3は他の組織型と比較し浸潤度が強く，予後不良であった。自験例の検討では，WHO分類は，胸腺腫の臨床病理学的特徴をよく反映している。

索引用語: 胸腺腫，WHO組織分類，正岡病期分類

Abstract: Abstract : Background: The World Health Organization (WHO) published an international histological classification in 1999.　Recently we checked our experiences against this classification to see whether it reflects the clinicopathological features of thymoma.
Methods: The subjects were 54 patients with thymoma, aged 14 to 77, who underwent surgery from January 1978 to March 2003 at Department of Surgery I, Fukushima Medical University Hospital or its affiliated hospitals.　Two classification systems were used: the WHO histological classification and Masaoka staging system.
Results: On the WHO criteria, the 54 patients were classified into 8 with Type A, 10 with Type AB, 7 with Type B1, 6 with Type B2 and 22 with Type B3.　One patient was excluded because the tumor had been cicatrized owing to irradiation.　According to the Masaoka staging system, all the patients were classified into 24 in Stage I, 19 in Stage II and 11 in Stage III.　None of the patients with Type A or AB and fewer than 30% of the patients with Type B1 or B2 were in Stage III, but as many as 8 (36.4%) of the patients with Type B3 were in Stage III.
　　No tumor-related death or recurrence occurred in the group with Type A or AB, but 1 such death and 1 recurrence occurred in the group with Type B1, 2 recurrences in the group with Type B2, and 3 tumor-related deaths in the group with Type B3.
　　Thymoma was associated with myasthenia gravis in 19 patients, 12 (63.2%) of whom had Type B3.　The tumor was associated with pure red cell aplasia in 4 patients: 1 with Type A, 2 with Type AB and 1 with Type B1.
　　Conclusions: The results of this study show that Type A and AB thymomas are the least invasive and have the best prognosis and that Type B3 thymoma is the most invasive and has the worst prognosis.　The WHO histological classification of thymoma accurately reflects the clinicopathological features of this tumor.

Key words: thymoma, WHO histological classification, Masaoka staging system