Division of Gastrointestinal and Neuroendocrine Tumors, European Institute of Oncology (IEO), IRCCS, Milan, Italy.
Division of Urology, European Institute of Oncology (IEO), IRCCS, Milan, Italy.
Am J Case Rep. 2022 Aug 29;23:e936552. doi: 10.12659/AJCR.936552.
BACKGROUND Merkel cell carcinoma (MCC) is a rare neuroendocrine neoplasm. The immunotherapy era has dramatically changed MCC prognosis, but unresponsive and progressive diseases after anti- programmed death-ligand 1 (PDL1) treatment still represent a challenge. MCC can metastasize in virtually every anatomical site, also during immunotherapy, and the reasons for primary resistance are debated. Testes are a rare metastatic site, accounting only 0.04% of autoptic detections in patients with more common malignancies. We report a case of a patient with metachronous and bilateral testes metastases after a previous radically treated MCC. CASE REPORT A 57-year-old man underwent radical surgery for left knee MCC. The oncologic follow-up was negative until 4 years later when the patient developed a right testis lesion. The patient underwent right orchiectomy for the suspicion of testicular primary malignancy, but the pathologist report revealed MCC metastasis. Subsequent radiologic assessment detected new bone metastases. The patient was treated with immunotherapy, experiencing a complete response. After 20 months of treatment, a further assessment revealed a new single left testis metastasis. A left orchiectomy was performed and immunotherapy was continued, maintaining a complete response. CONCLUSIONS There are few reports that MCC can be associated with uncommon metastases in testicular tissue. The present case suggests the testis represents another "sanctuary" site for the metastasizing process and host immune response. Considering the dramatic impact of immunotherapy in MCC prognosis, the study of these rare cases may aid the understanding of intrinsic resistance mechanisms to anti-PDL1, which affects a percentage of MCC patients.
默克尔细胞癌（Merkel cell carcinoma，MCC）是一种罕见的神经内分泌肿瘤。免疫治疗时代极大地改变了 MCC 的预后，但抗程序性死亡配体 1（PDL1）治疗后无反应和进行性疾病仍然是一个挑战。MCC 几乎可以转移到所有解剖部位，甚至在免疫治疗期间也是如此，而原发性耐药的原因仍存在争议。睾丸是罕见的转移部位，在更常见的恶性肿瘤患者的尸检中仅占 0.04%。我们报告了一例先前根治性治疗 MCC 后出现同步双侧睾丸转移的患者。
一名 57 岁男性因左膝 MCC 接受根治性手术。肿瘤随访结果为阴性，直到 4 年后，患者出现右侧睾丸病变。患者因怀疑睾丸原发性恶性肿瘤而行右侧睾丸切除术，但病理报告显示 MCC 转移。随后的影像学评估发现新的骨转移。患者接受免疫治疗，完全缓解。治疗 20 个月后，进一步评估显示左侧睾丸出现新的单发转移。行左侧睾丸切除术，并继续进行免疫治疗，保持完全缓解。
MCC 罕见转移至睾丸组织的报道较少。本病例提示睾丸是转移过程和宿主免疫反应的另一个“避难所”部位。鉴于免疫治疗对 MCC 预后的巨大影响，对这些罕见病例的研究可能有助于了解抗 PDL1 的内在耐药机制，这影响了一部分 MCC 患者。
