Giant testicular tumors, defined as masses with volumes exceeding 10 times the normal testicular volume, are exceptionally rare, with only a few cases reported globally [4,5,6,7]. Delayed presentation is frequently associated with stigma and psychological distress. In our case, the patient had been socially withdrawn and delayed seeking medical care for 3 years.

We conducted a literature search using PubMed and Ichushi-Web with the keywords ‘giant testicular tumor,’ ‘giant seminoma,’ and ‘giant germ cell tumor.’ The majority of previously published cases originated from Japan and were primarily individual case reports [8,9,10,11,12]. Potential contributing factors include delayed medical consultation related to cultural hesitation toward genital examination, social isolation, and disparities in healthcare access. Table 1 summarizes the 68 cases of giant testicular tumors reported in Japan. The median patient age was 37 years, and the median specimen weight was 1800 g. Histopathological findings indicated that 71% of the cases were seminomas, and 12% were ultimately categorized as nonseminomas based on elevated AFP levels.

Retroperitoneal lymph node involvement was observed in 55% of the cases. Distant metastases commonly involved the lungs (44%), mediastinum (17%), bones (17%), inguinal nodes (13%), and cervical nodes (9%). To the best of our knowledge based on our literature search, we were unable to identify any prior reports of contralateral inguinal lymph node metastasis in giant testicular tumors.

Radical orchiectomy remains both diagnostic and therapeutic and is recommended for initial management unless systemic chemotherapy is urgently needed.　Among the cases in the literature, 45% of patients underwent neoadjuvant chemotherapy, which likely reflects surgical inoperability at presentation. Only a few patients required reconstructive skin procedures, and there is no consensus as to whether immediate or delayed valvuloplasty is superior. We employed VAC therapy to minimize the risk of infection in the pubic area and reduce skin defects before performing delayed reconstruction. Compared with conventional gauze dressing, VAC therapy accelerates granulation, decreases bacterial burden, and reduces wound edema, thereby facilitating more effective preparation for skin grafting or flap reconstruction.

Although this patient had Stage IIIA disease, surgical complete remission (CR) was achieved after complete resection of the primary tumor and metastatic lymph nodes. For Stage IIIA patients who achieve surgical CR, current guidelines do not provide definitive recommendations, and both postoperative surveillance and adjuvant chemotherapy remain acceptable options, as evidence is limited. Therefore, we referred to the rationale derived from high-risk Stage I nonseminoma—not as a staging substitute, but as a conceptual framework—where adjuvant chemotherapy is used after complete resection, to guide management in this rare clinical scenario. Although BEP is the standard regimen, VIP is an accepted alternative when bleomycin is contraindicated. Based on the patient’s age and smoking history, two cycles of VIP were selected to avoid bleomycin-induced pulmonary toxicity.

Giant testicular tumors are uncommon in high-resource countries but continue to be reported in disproportionately high numbers in Japan. Delayed presentation is a well-recognized issue in testicular cancer and is often associated with a lack of awareness or hesitation to seek medical care. Prior studies have shown that testicular self-examination (TSE) and increased awareness of scrotal abnormalities may facilitate earlier presentation and reduce the likelihood of advanced-stage disease [13]. In the context of giant testicular tumors, which frequently arise from prolonged neglect, improved education on scrotal abnormalities and the high curability of testicular cancer may help mitigate delays in diagnosis.