當睪丸疼痛掩蓋惡性腫瘤：非典型臨床表現的混合型睪丸生殖細胞瘤

孫浩議¹、陳生文^1,2、張彰琦^1,2、程威銘^1,2、邱逸淳^2,3

¹臺北市立聯合醫院忠孝院區外科部泌尿科

²國立陽明交通大學醫學院

³臺北市立聯合醫院陽明院區外科部泌尿科

When Testicular Pain Masks Malignancy: A Mixed Germ Cell Tumor with an Unusual Clinical Presentation

Hao-Yi Sun ¹, Sheng-Wen Chen ^1,2, Chang-Chi Chang ^1,2, Wei-Ming Chen ^1,2, Yi-Chun Chiu ^2,3

¹ Division of Urology, Department of Surgery, Zhongxiao Branch, Taipei City Hospital

² National Yang Ming Chiao Tung University, School of Medicine, Taipei, Taiwan

³ Division of Urology, Department of Surgery, Yangming Branch, Taipei City Hospital

Introduction:

Testicular germ-cell tumors (GCTs) are the most common solid malignancies in young adult men and often present with a characteristic painless scrotal mass ^1,2. However, mixed GCTs, composed of multiple malignant elements such as yolk-sac tumor, choriocarcinoma, and teratoma, may occasionally manifest with atypical symptoms, increasing the risk of delayed diagnosis ³. Early recognition is essential because non-seminomatous components can progress rapidly but respond well to cisplatin-based chemotherapy. Here, we report a young man whose mixed GCT presented primarily as persistent testicular pain, clinically resembling benign inflammatory conditions, highlighting the diagnostic challenges posed by non-classical presentations.

Case presentation:

A 35-year-old man presented with a one-month history of persistent left testicular pain, accompanied by mild nausea and decreased appetite. He denied fever, trauma, urinary symptoms, or previous scrotal disease. Physical examination revealed a firm, non-tender mass in the left testis without gynecomastia or palpable inguinal lymphadenopathy. Scrotal ultrasonography demonstrated a 5.2 × 4.4 cm heterogeneous, hypervascular intratesticular mass highly suspicious for malignancy. Laboratory evaluation showed markedly elevated tumor markers, including AFP 312 ng/mL, β-hCG 2156 mIU/mL, and LDH 193 U/L. A contrast-enhanced abdominal CT scan confirmed a left testicular tumor with suspected para-aortic and left common iliac lymphadenopathy, without evidence of distant metastasis.

He underwent left radical orchiectomy, followed by gross pathology revealing a 7.5 × 5.0 × 4.0 cm mixed germ-cell tumor composed predominantly of yolk-sac tumor (approximately 60%), with a minor choriocarcinoma component (around 5%) and mature teratomatous elements. Immunohistochemical staining supported the mixed histology, showing AFP and PLAP positivity in the yolk-sac component, focal Glypican-3 reactivity, and GATA-3 positivity in the choriocarcinoma component. Postoperative tumor markers declined appropriately. Pelvic MRI demonstrated no residual disease or local recurrence, and chest CT revealed no pulmonary metastases. Because of the elevated postoperative tumor markers and the presence of non-seminomatous elements, he received systemic BEP chemotherapy beginning in one month. He tolerated the regimen well, without major toxicity, and subsequent imaging confirmed complete radiologic response with normalization of tumor markers.

Conclusion:

This case demonstrates that mixed germ-cell tumors may initially present with atypical symptoms such as isolated testicular pain, potentially mimicking benign inflammatory conditions. Early imaging and tumor marker assessment remain critical in young men with persistent unilateral testicular discomfort. Timely orchiectomy with appropriate staging, followed by cisplatin-based chemotherapy, can achieve excellent outcomes even in tumors with aggressive non-seminomatous elements. Long-term surveillance is essential to ensure durable remission.

Discussion:

This case underscores the diagnostic challenge posed by pain-dominant presentations of testicular germ-cell tumors (GCTs). Although most GCTs classically manifest as a painless mass, pain can occur when rapid intratesticular expansion leads to capsular stretching, irritation of the spermatic cord neurovascular bundle, or increased intratesticular pressure ². In mixed GCTs, components such as yolk-sac tumor and choriocarcinoma may undergo intratumoral hemorrhage or necrosis, further stimulating nociceptive pathways and producing symptoms that mimic epididymo-orchitis ³. These mechanisms explain why patients may present with persistent discomfort rather than overt swelling or systemic signs. The misleading nature of pain-centered presentations often results in an initial assumption of benign inflammation, potentially delaying appropriate oncologic evaluation. This case illustrates that persistent unilateral testicular pain, even in the absence of fever, urinary symptoms, or leukocytosis, warrants early ultrasonography and tumor-marker assessment. Moreover, the tumor’s histologic heterogeneity suggests variable growth kinetics and susceptibility to mechanical stress, contributing to symptom variability ^3,4. Recognizing the biological basis of pain in testicular tumors is essential, as timely identification of malignant causes supports curative management and prevents diagnostic delay in young symptomatic patients.