後腎性腺腫の2例

Abstract

症例1(54歳男性)。健診で左腎腫瘍を指摘され, 画像所見により腎細胞癌が疑われた。初診1ヵ月後に左腎部分切除術を施行したところ, 病理組織学的所見では腫瘍は小型均一な腫瘍細胞が構成する乳頭管状構築からなっており, 免疫組織化学的所見ではCD57, WT-1が陽性であった。以上より, 本症例は後腎性腺腫と診断され, 術後1年経過現在, 再発の徴候はみられていない。症例2(40歳男性)。左側腹部痛を主訴とした。エコー上, 軽度の左水腎が認められ, CTでは左腎盂に造影効果を伴う壁肥厚が確認された。また, 左逆行性腎盂造影では上部尿管の狭窄がみられ, 尿管鏡下腎盂生検で尿路上皮癌G2と診断された。初発症状から2ヵ月後, 左腎尿管全摘除術を施行したところ, 切除腎の実質内に微小結節が偶発的に見い出され, 病理組織学的所見等により小型ながら後腎性腺腫に相当するものと考えられた。目下, 術後より10ヵ月経過で再発の徴候はみられていない。

We report 2 cases of metanephric adenoma a rare form of adenoma. One case occurred in a 54-year-old male preoperatively diagnosed with renal cell carcinoma who underwent left partial nephrectomy for a tumor 2 cm in size. Histology revealed a tumor with papillotubular structures consisting of small, uniform tumor cells. In immunohistochemical staining, tumor cells were positive for CD57 and WT-1. Thus, the patient was diagnosed with metanephric adenoma. The other case occurred in a 40-year-old male who underwent left nephroureterectomy for carcinoma of the renal pelvis. Carcinoma of the left renal pelvis was diagnosed as pT3N0M0. Incidental micronodules 2 mm in size and consisting of immature tubular structures were noted in the renal cortex. In immunohistochemical staining, tumor cells were positive for CD57 and WT-1, and the patient was diagnosed with metanephric adenoma. The aforementioned tumors frequently occur in middle-aged women and are often well-defined tumors that project from the renal surface outwards. On angiography, they have a hypovascular pattern and resemble papillary renal carcinoma. Preoperative differentiation of renal cell carcinoma and nephroblastoma is difficult. Mistaking such tumors for malignant tumors and subjecting patients to unnecessary adjuvant therapy must be avoided.