特殊組織型食道癌の病理組織学的・免疫組織学的特徴

Histopathologic and Immunohistochemical Characteristics of Special Variants of Esophageal Carcinoma

要旨　特殊組織型の食道癌18例（小細胞癌5例，カルチノイド1例，類基底細胞-扁平上皮癌8例，腺扁平上皮癌4例）においてそれらの病理組織学的・免疫組織学的特徴を検討し，類基底細胞-扁平上皮癌と腺様嚢胞癌との鑑別困難1例と非小細胞型未分化癌10例について免疫組織学的所見を加味した再分類を試みた．免疫組織学的に，小細胞癌はケラチンでは高分子(－)，低分子(＋)であり，chromogranin Aは必ずしも陽性でなくCD56が最も有用であった．類基底細胞-扁平上皮癌ではケラチンでは高分子(＋)に加えて，様々な割合でCEA，アクチン，vimentin(＋)とbcl-2(＋)が特徴的であり，多分化能を有する腫瘍であることが示された．腺扁平上皮癌は，腺癌と扁平上皮癌のそれぞれに対応した染色性であった．すべての症例において腺様嚢胞様構造部でさえもS-100は陰性であり，腺様嚢胞癌に合致する症例はみられなかった．鑑別診断には病理組織学的所見が最も重要であることは言うまでもないが，非小細胞型未分化癌や鑑別が困難であった例でも免疫組織学的所見を加味するとある組織型へ分類することができ，免疫組織学的所見の有用性が示された．

　The histopathologic and immunohistochemical characteristics of special variants of esophageal carcinoma were evaluated. Eighteen cases of special variants (5 small cell carcinomas, 1 carcinoid tumor, 8 basaloid-squamous carcinomas and 4 adenosquamous carcinomas) and 10 cases of undifferentiated carcinomas were selected for this study. Immunohistochemical results were as follows. With regard to small cell carcinoma, high molecular weight cytokeratins (CK903 and CK14) were negative, low molecular weight cytokeratin (CAM5.2) was positve, chromogranin A was not always positive, and CD56 was diffusely positive. With regard to basaloid-squamous carcinoma, high molecular weight cytokeratins (CK903 and CK14) and bcl-2 were always positive and various degrees of CEA, actin and vimentin positive cells were present. With regard to adenosquamous carcinoma, high molecular weight cytokeratins (CK903 and CK14) were positive for a squamous cell carcinoma component and low molecular weight cytokeratin (CAM5.2) and CEA were positve for an adenocarcinoma component. In all special variants, even in glandular or adenoid cystic-like components, S-100 protein was negative. From these findings, the immunohistochemical stains are considered to be useful for differential diagnosis of special variants of esophageal carcinoma.