前立腺癌精査中に発見された精巣原発神経内分泌腫瘍の1例

A case of primary neuroendocrine tumor of the testis detected during evaluation for prostate cancer

精巣腫瘍は一般的に若年成人に好発する腫瘍であり，大部分（約95％）は胚細胞性腫瘍である。しかし，高齢者では胚細胞性腫瘍はまれであり，転移や悪性リンパ腫をはじめとするその他の腫瘍の頻度が上がる。今回我々は，70代と高齢な患者の前立腺癌精査中に偶発的に発見され，手術された精巣原発神経内分泌腫瘍の症例を経験したので報告する。

We report a rare case of a primary neuroendocrine tumor（NET）of the testis in a man in his 70s, incidentally discovered during evaluation for suspected prostate cancer. MRI revealed suspicious lesions in the prostate and an enlarged right testis with heterogeneous low signal intensity on T2-weighted imaging. Contrast-enhanced CT demonstrated a well-enhancing testicular mass and a solitary pulmonary nodule. The patient underwent high orchiectomy and prostate biopsy, which revealed a well-differentiated testicular NET and prostate adenocarcinoma. The pulmonary lesion was subsequently diagnosed as squamous cell carcinoma. Although rare, testicular NET should be considered in the differential diagnosis of testicular masses in elderly patients.