若年者の直腸に多発した炎症性ポリープの1例

Multiple Inflammatory Polyps of the Lower Rectum, Report of a Case

要旨　16歳の男性の直腸下部に多発した炎症性ポリープを報告した．患者は4か月前より持続する血便と排便時痛を訴え来院し，X線検査と内視鏡検査で，肛門輪に接した直腸にほぼ全周性に発生した大小様々な結節状の隆起性病変が見出された．生検の組織診では悪性の所見はみられなかったが，治療の日的で経肛門的にポリープ切除術がなされた．切除ポリープは16個に及び，多くは0.5～1.5cmの大きさであったが，最大のものは2×3cmで亜有茎性であった．いずれのポリープも組織学的には同一で，増生した肉芽組織ないし線維組織が主体で一部で過形成性腺管がみられるにすぎなかった．表層はびらん性で滲出物の付管がみられた．腺腫性細胞や悪性細胞は全くみられず，ポリープは組織障害の修復に閨連して生じた炎症性のものと考えられた．

　A case of multiple inflammatory polyps arising in the lower rectum is reported. A 16 year-old boy was admitted to a hospital, because he complained of difficulty indefecation, anal pain and hemorrhage. X-ray and endoscopic examinations disclosed multiple sessile and pedunculated polyps encircling the anal ring. The surface of the polyps was necrotic and hemorrhagic. In pathological examination of the biopsy, the polypoid lesions were found not neoplaslic but inflammatory. The polyps were resected surgically.

　Sixteen large and small polyps were gotten. The largest one measured about 2×3 cm. The others were 0.5～1.0 cm in diameter. Histopathologically, they consisted of inflammatory stromal tissues and a few dilated, hyperplastic crypts. Each crypt was composed of normal-appearing columnar and goblet cells. Neither adenomatous nor malignant cells were found. The stroma was edematous, composed of fibrous tissues, and infiltrated by mononuclear cells focally by neutrophils. The surface of the polyp was necrotic and coagula of exudate were seen. In some polyps, bundles of smooth muscle fibers without specific orientation were seen in the stroma. The polyps were diagnosed as "inflammatory polyps".

　This kind of polyp appears to arise following mucoral injury of the rectum, especially of the lower rectum near the anal ring. Causative factors include a mass of fecal and other mechanical injuries. Following regeneration, the overgrowth of stromal elements happens to occur, which may cause narrowing of the lumen, resulting in further mucosal injury by fecal stream. This implies that the inflammation continues, leading to polypoid prominences of the lower rectum. The situation is analogous to the condition known as "solitary ulcer syndrome" of the rectum.