A case of papillary renal cell carcinoma suggestive of Bellini duct origin

Abstract

76歳男, 健康診断のため施行された腹部CTで左腎腫瘍が疑われ根治的左腎摘出術が施行された。摘除腎の髄質に割面黄褐色で直径約2cmの腫瘍を認め病理組織学的に円柱状で好酸性胞体を有する悪性細胞が乳頭状に増殖していた。レクチンおよび2種のモノクローナル抗体を用いた検討では, Soybean agglutinin, Peanut agglutinin, Dolichos biflorus agglutinin, Lotus tetragonolobus agglutininおよびCytokeratinは弱陽性でTamm-Horsfall proteinが陰性であった。腫瘍の肉眼的および組織学的所見は, 本腫瘍がベリニ管上皮由来であることを強く示唆した。患者は手術後1年を経たが腫瘍の再発を認めず健在である

A case of Bellini duct carcinoma is reported. A left renal tumor was detected by abdominal computerized tomography in a 76-year-old male, although he had no symptoms, such as hematuria, weight loss or flank pain. Radical nephrectomy was performed under the diagnosis of renal cell carcinoma in the left kidney. Macroscopic examination of the resected kidney revealed a tumor 2.0 cm in diameter, with a yellow-brown cut surface, located in the renal medulla. Histological examinations showed malignant tumor cells with eosinophilic cytoplasm with a papillary growth pattern. Immunohistostaining examinations using Lectin and two kinds of monoclonal antibodies demonstrated no significant staining with soybean agglutinin, peanut agglutinin, Dolichos biflorus agglutinin, Lotus tetragonolobus agglutinin or cytokeratin, and negative staining with Tamm-Horsfall protein. Although the results of immunohistostaining did not provide support, both macroscopic and microscopic findings strongly suggested that this tumor originated from Bellini duct epithelium (Bellini duct carcinoma). The patient is alive with no evidence of disease 1 year after surgery. Bellini duct carcinoma is a rare malignant condition and the prognosis is usually poor. Differential diagnosis from other renal or pelvic tumors is difficult and long-term careful follow-up is necessary.