—大腸非上皮性ポリープの鑑別診断—非腫瘍性ポリープ—病理診断の立場から

Differential Diagnosis of Nonneoplastic Nonepithelial Polyps of the Colon

要旨●大腸非上皮性非腫瘍性ポリープとは病理組織学的に大腸上皮の増殖を伴わない良性病変で，反応性に増生する細胞，あるいは異所性に存在する細胞によって隆起した病変と考えられる．多くは粘膜下腫瘍様に隆起し，時に腫瘍性ポリープとの鑑別に苦慮するものもある．リンパ濾胞性ポリープは悪性リンパ腫との鑑別が重要で，限局性腫瘤を形成するALアミロイドーシスや発赤を伴う扁平隆起を呈する腸管子宮内膜症は肉眼的に腫瘍性病変との鑑別が困難なときがあるが，生検組織でアミロイドや子宮内膜組織を確認することで容易に鑑別できる．腸管囊胞様気腫症は腹部CTなど臨床画像で鑑別が可能であるが，生検診断でも含気囊胞や空気に反応した多核巨細胞や組織球の集簇を認めることで診断に寄与することができる．

　Nonneoplastic nonepithelial polyps of the colon are benign, elevated lesions without colonic epithelial proliferation, and they are caused by reactive or ectopic cells. Many of these polyps present as submucosal tumor-like masses ; moreover, it is often difficult to distinguish these benign polyps from neoplastic ones. Lymphoid polyps must be differentiated from malignant lymphomas. Amyloid tumors（amyloidomas）, in patients with amyloid light chain amyloidosis and mucosal intestinal endometriosis, which present as reddish flat polyps that are sometimes difficult to distinguish from neoplastic lesions by gross examination, can be easily diagnosed by the biopsy of the amyloid or endometrial tissue. Furthermore, pneumatosis cystoides intestinalis can be diagnosed by abdominal computed tomography but biopsy can also facilitate the diagnosis by detecting air-containing cysts, air-responsive multinucleated giant cells, and histiocytic aggregates.