Abbreviations & Acronyms AMACR = a-methylacyl CoA racemase ANN = artificial neural networks BSI = bone scan index CT = computed tomography FDG-PET = fluorodeoxyglucose-positron emission tomography HLA = human leukocyte antigen HS(n) = Hot spot number IMDC = International Metastatic RCC Database Consortium IO = immune-oncology MTSCC = mucinous tubular and spindle cell carcinoma RCC = renal cell carcinoma TKIs = tyrosine kinase inhibitors WHO = World Health Organization

Introduction The spontaneous regression of metastases, which mostly occurs after surgical resection of the primary tumor, has been described in various malignancies, including renal cell carcinoma. The involvement of the host immune system is currently postulated as the underlying mechanism. Case presentation We present a case of metastatic clear‐cell renal cell carcinoma that achieved complete spontaneous regression of multiple pulmonary metastases preceded by normalization of serum immune markers after cytoreductive nephrectomy. The patient remained disease free for 3 years without any systemic therapy, suggesting that postoperative normalization of serum immune markers may indicate recovery of the host immune system, which prevents tumor recurrence. Conclusion Monitoring of serum immune markers may be useful to identify patients with recovered immune function and, therefore, may not require systemic therapy. Similarly, the case suggests a potential role of cytoreductive nephrectomy in the contemporary management of metastatic renal cell carcinoma.

Introduction Treatment‐related neuroendocrine prostate cancer, a rare and aggressive malignancy that emerges during androgen deprivation therapy characterized by low serum prostate‐specific antigen concentrations, is challenging to monitor because it is associated with predominantly visceral and lytic bone metastases. Case presentation We describe the case of a 69‐year‐old man with treatment‐related neuroendocrine prostate cancer in whom the treatment response could be monitored using whole‐body diffusion‐weighted magnetic resonance imaging in addition to serum concentrations of neuroendocrine markers. The patient responded well to platinum‐based chemotherapy and achieved a complete response, as evidenced by these diagnostic modalities. Conclusion Our case suggests that whole‐body diffusion‐weighted magnetic resonance imaging is useful in disease management for treatment‐related neuroendocrine prostate cancer as well as the potential evaluation of mixed responses and treatment resistance.

Management of abdominal compartment syndrome (ACS) due to renal injury is important. A 21-year-old man was taken to an emergent care unit with grade IV right kidney trauma and hypovolemic shock due to a road traffic injury. Despite twice targeted transcatheter arterial embolization of a renal artery, intravesical pressure increased and blood pressure was difficult to maintain. After right nephrectomy and ligated the bleeding lumbar arteries and veins to avoid ACS, the patient's general condition improved, and he did not develop ACS. Monitoring of intravesical pressure may be useful for deciding treatment strategy.

Cryptococcal granulomatous prostatitis is extremely rare, and there have been few reports of its diagnosis by prostate needle biopsy. The patient, an 81–year–old man, was receiving immunosuppressive treatment for rheumatoid arthritis. He had an oropharyngeal ulcer, and it was diagnosed alongside a methotrexate-related diffuse large B-cell lymphoma. A systemic imaging examination revealed a prostatic tumor-like mass clinically suspected to be prostatic cancer, and a needle biopsy was performed. The biopsy specimen showed various types of inflammatory cell infiltration, and suppurative granuloma and caseous granuloma were observed. Both granulomas showed multiple round and oval organisms that were revealed with Grocott methenamine silver staining. Acid–fast bacilli were not detected by Ziehl–Neelsen staining. We histologically diagnosed granulomatous prostatitis caused by Cryptococcus infection. Caseous granulomas often develop in the prostate after bacillus Calmette–Guerin immunotherapy for bladder cancer, although the possibility of cryptococcal granulomatous prostatitis should also be considered.