田中 亨

【背景】体腔液中に出現する反応性中皮細胞は,ときに悪性細胞との鑑別を要する.今回,卵巣癌の術中腹水細胞診で腺癌細胞との鑑別を要した反応性中皮細胞の1例を経験したので,その所見を報告する.【症例】患者は40歳代女性で,下腹部痛と腰痛を主訴に当センターを紹介受診した.CT・MRI検査にて腹膜転移を伴う卵巣癌が疑われた.入院後,子宮および両側付属器,腹膜結節,大網切除術を施行し,術中腹水細胞診検査を行った.その腹水細胞診標本では,炎症性背景に,多空胞状でライトグリーン淡好性の細胞質を有するやや大型の細胞集塊が少量認められた.明細胞癌を含めた腺癌細胞との鑑別を要したが,核の腫大や核クロマチンの濃染性,核形不整,核・細胞質比の増高はいずれも軽度で,細胞質は小空胞状を示し,細胞の重積性は目立たなかった.よって,細胞判定は陰性とし,中皮細胞の反応性変化と報告した.最終的な病理診断は右付属器原発の高異型度漿液性癌,骨盤外腹膜転移あり,大網転移なし,FIGO Stage IIIC期となった.【結論】腹水の細胞診断において中皮細胞の形態学的多様性を理解することは,腺癌を含めた悪性細胞との鑑別に有用と考えられる.(著者抄録)

We report a unique case of a 74-old man, who presented with double cancers, showing metastasis of pancreatic cancer to colon cancer. Histopathological examination after surgery revealed that the patient had ascending colon cancer, which metastasized to the liver (pT4N0M1), as well as pancreatic cancer (pT2N1M1) that metastasized to the most invasive portion of the colon cancer, namely the serosal to subserosal layers. Although the mechanisms for this scenario have yet to be elucidated, we speculate that the metastatic pancreatic carcinoma overtook the stromal microenvironment of the colon cancer. Namely, the cancer microenvironment enriched by cancer-associated fibroblasts, which supported the colon cancer, might be suitable for the invasion and engraftment by pancreatic carcinoma. The similarity of histological appearance might make it difficult to distinguish metastatic pancreatic carcinoma within colon cancer. Furthermore, the metastasis of pancreatic carcinoma in colon carcinoma might be more common, despite it not having been previously reported.