直腸のBarium Fleck（Barium Granuloma）―内視鏡および病理学的所見を中心として

Barium Fleck (Barium Granuloma) of the Rectum: Endoscopical observation and pathological findings

　近年，直腸鏡や大腸ファイバースコープ検査においても，微小癌をはじめとして微細な大腸粘膜病変の観察に関心がもたれている．われわれは最近，直腸粘膜に注腸検査時に用いられた硫酸bariumの沈着によると思われる小白斑（barium fleck），およびbarium肉芽腫（barium granuloma）を25例に観察した．直腸のbarium granulomaは1954年にBeddoeら¹⁾により初めて報告されてから諸外国には数十例の報告をみるが，本邦にはほとんどなく，特に小白斑としてみられるbarium fleckに関しての報告はみられない．そこで今回はこれらの病変の内視鏡的所見，および病理組織学的所見を中心に，若干の考察を加えて報告する．

　Recently, in 25 cases barium fleck (barium granuloma) was observed in the rectal mucosa by endoscopic examination. All of these cases had had barium enema study from 1 to 19 weeks before endoscopic examination.

　Endoscopically, these lesions were seen as white or yellow white colored flecks in 23 cases, or ulcer in 2. The size of the lesion varied from 3 to 12 mm in greatest diameter. The majority of these lesions were seen between 5～10 cm from anal verge on anterior wall of the rectum. Accumulation of radiopaque substances in the mucosal and submucosal layer were seen by ultrasoft X-ray studies of the biopsy or resected specimens.

　Histopathologically, accumulation of barium-laden histiocytes in lamina propria mucosae and submucosal layer of the rectum was observed. Yellowish green crystals of barium sulfate were easily identified in the cytoplasm of histiocytes, or sometimes freely in the granulation tissue, and were doubly reflactile with polarized light. Inflammatory reaction was slight, consisting chiefly of lymphocytes and plasma cells in majority of cases. But, in ulcelated cases, more typical granulomatous reaction such as fibroblastic proliferation, polymorphonuclear leucocyte infiltration or giant cell infiltration, was observed.

　The probable pathogenesis of these lesions is thought to be laceration of the mucosa by the enema tip, overdistention of the rectum, or high pressure infusion of barium contrast medium.

　As a rule, treatment of these lesions of the rectum is conservative despite the continued presence of barium crystals in the tissue.