癌や炎症と鑑別が困難な小腸悪性リンパ腫の臨床病理学的特徴―X線・肉眼所見を中心に

Malignant Lymphoma of the Small Intestine, whose Initial Diagnosis was Obscure─A Clinicopathological Study with Special Reference to Radiographic, Macrosocpic and Histologic Features

要旨　小腸悪性リンパ腫132例を，癌や良性疾患と鑑別を要した鑑別困難例（n＝47）と典型例（n＝85）に分け，両者の特徴を比較した．典型例と比べ，鑑別困難例では，十二指腸病変，多発例，組織型でMALTやNK/T細胞性リンパ腫，肉眼型でびまん型や混合型の頻度が高かった．また，鑑別困難例では外科切除が少なかったが，病期や予後に差はなかった．鑑別困難例のうち，癌などの腫瘍と鑑別を要した例はdiffuse large B-cell lymphomaや隆起型，限局性炎症と誤診した例はMALTリンパ腫や潰瘍型，アミロイドーシスなどのびまん性疾患に類似した例はNK/T細胞性やびまん型が多かった．良性リンパ濾胞過形成と鑑別困難な例にはMLP型のマントル細胞リンパ腫などがみられた．以上より，小腸リンパ腫の診断には各組織型に特徴的な肉眼所見を理解して，適切な画像検査を行うことが重要と考えられた．

　The clinicopathological features of 47 patients with primary malignant lymphoma of the small intestine that had been misdiagnosed as carcinomas or inflammatory diseases on radiography（Difficult group）were retrospectively compared with 85 patients with typical small intestinal lymphomas（Typical group）. Compared to the Typical group, the Difficult group more frequently had MALT lymphomas and NK/T-cell lymphomas on histology, diffuse and combined/other forms on macroscopy, the involvement of the duodenum, and multiple lesions. Surgical resection was less frequently performed in the Difficult group than in the Typical group. No differences between the two groups were observed in the clinical stages or the prognosis of patients. In the Difficult group, the common histologic and macroscopic types were diffuse large B-cell lymphomas and polypoid forms in cases misdiagnosed as non-lymphomatous tumors, MALT lymphoma and ulcerative forms in those misdiagnosed as localized inflammation, NK/T-cell or MALT lymphomas and diffuse form in those misdiagnosed as diffusely infiltrating diseases, and mantle cell, MALT or follicular lymphomas and MLP forms in those misdiagnosed as benign lymphoid polyposis. It is necessary to understand the characteristic macroscopic findings in each histologic type for an accurate clinical diagnosis of small intestinal lymphomas.