Yolk sac tumor after post-detorsion changes in a torsed undescended testis: a case report

Introduction

Cryptorchidism is among the most common congenital genitourinary anomalies in boys; its prevalence decreases with age but remains approximately 1% at 12 months (1). Beyond its impact on fertility potential, cryptorchidism is a well-established risk factor for testicular germ-cell tumors, with studies reporting a several-fold increase in relative risk compared with normally descended testes (2). Testicular torsion is a time-critical surgical emergency and represents roughly one quarter of operative explorations for acute scrotum in children (3). Torsion of an undescended testis is rare and often presents atypically; this atypical presentation may delay diagnosis and increase the likelihood of testicular loss. Malignant transformation after testis-sparing detorsion for cryptorchid torsion has been reported only sporadically (4). Here, we describe a toddler who developed a yolk sac tumor 6 months after detorsion and orchiopexy for cryptorchid torsion, and we discuss perioperative implications for risk stratification and surveillance. We present this article in accordance with the CARE reporting checklist (available at https://tau.amegroups.com/article/view/10.21037/tau-2026-1-0009/rc).

Case presentation

A 2-year-5-month-old boy presented with an 8-hour history of right inguinal and scrotal pain and swelling accompanied by nausea and vomiting, without fever or abdominal symptoms. Cryptorchidism had not been previously diagnosed, and the family reported no prior evaluation or follow-up. Ultrasound demonstrated a mixed-echoic mass in the right inguinal region with an enlarged right testis and epididymis, heterogeneous intratesticular echogenicity, and absent blood flow, suggesting spermatic cord/testicular torsion (Figure 1A). Physical examination showed marked right inguinal and scrotal erythema and swelling with tenderness; a testis-like mass was palpated in the inguinal region, while no definitive testis was palpable in the right hemiscrotum. The left testis was palpable in the scrotum and unremarkable.

Figure 1 Initial presentation and detorsion. (A) Preoperative ultrasound showing an enlarged right undescended testis/epididymis with heterogeneous echogenicity and absent detectable intratesticular blood flow. (B) Intraoperative view demonstrating 720° clockwise torsion of the testis/epididymis/spermatic cord. (C-E) Follow-up ultrasonography at 1, 3, and 5 months after detorsion demonstrated preserved perfusion without a definable mass. No dye was used during the procedure. The bluish discoloration of the testis was attributable to ischemic changes and lighting conditions during intraoperative photography.

Emergency exploration under general anesthesia revealed dense inflammatory adhesions of the tunica vaginalis. The right testis, epididymis, and spermatic cord were twisted 720° clockwise (Figure 1B). After counterclockwise detorsion and warm saline packing for 15 minutes, the testis was graded Assessment of Recovery of Degenerative Changes and Atrophy (ARDA) III. The intraoperative diagnosis was right testicular torsion with cryptorchidism. The family was counseled regarding the risks of testicular salvage; they opted for testis preservation, and orchiopexy was performed.

Postoperative recovery was uneventful. Early postoperative ultrasound showed heterogeneous enhancement with reduced focal perfusion in the right testis, thickened surrounding soft tissue, and an enlarged epididymal head-findings interpreted as postoperative change-along with a thickened spermatic cord. The caregivers were informed about the possibility of testicular atrophy or dysplasia. Follow-up ultrasounds at 1, 3, and 5 months demonstrated acceptable perfusion of the testis and epididymis without new abnormalities (Figure 1C-1E).

Approximately 6 months after surgery, the patient was readmitted for a 3-week history of progressive right scrotal enlargement. The scrotal skin was mildly erythematous with prominent superficial veins and no marked tenderness. Ultrasound demonstrated a mixed-echoic lesion in the right hemiscrotum; hemorrhagic necrosis after torsion was considered, but a mass lesion could not be excluded (Figure 2A). Examination revealed a firm, mobile scrotal mass (approximately 4 cm × 3 cm × 2 cm) with dilated superficial vessels (Figure 2B). Magnetic resonance imaging (MRI) of the pelvis and brain showed a right scrotal mass with thickened and markedly enhancing right spermatic cord, suspicious for a tumor of gonadal origin (Figure 2C). Serum alpha-fetoprotein (AFP) was 1,258.7 ng/mL; neuron-specific enolase was 25.66 ng/mL.

Figure 2 Second admission: progressive scrotal mass. (A) Ultrasound demonstrating a mixed-echoic lesion in the right hemiscrotum. (B) Clinical photograph showing right scrotal enlargement with superficial venous dilation. (C) Pelvic magnetic resonance imaging showing a right scrotal mass with thickened and markedly enhancing right spermatic cord, suspicious for a gonadal tumor.

Preoperative serum β-human chorionic gonadotropin (β-hCG) was 0.05 mIU/mL (reference range ≤2.5 mIU/mL), and postoperative β-hCG remained within normal limits at 0.05 mIU/mL. Chest radiography demonstrated no evidence of pulmonary metastasis, and abdominal as well as inguinal ultrasonography showed no suspicious retroperitoneal or inguinal lymphadenopathy. Based on the available imaging findings and subsequent intraoperative assessment, the tumor was considered clinical stage I.

After preoperative evaluation and exclusion of surgical contraindications, laparoscopic exploration combined with radical right orchiectomy was performed. The laparoscopic procedure was performed primarily to facilitate surgical management and secure high ligation of the spermatic cord rather than as a substitute for imaging-based oncological staging. Considering the patient’s previous emergency surgery for testicular torsion, significant adhesions were anticipated in the inguinal region. To minimize tumor manipulation and ensure adequate oncologic control, a combined approach was adopted. Laparoscopic exploration was first performed to evaluate the inguinal canal, spermatic vessels, and potential metastatic disease. High ligation of the spermatic cord was achieved laparoscopically at the internal inguinal ring. The tumor specimen was subsequently removed through a scrotal incision with minimal compression. This approach was considered safer than conventional inguinal dissection in the setting of prior surgery-related adhesions and allowed secure oncologic control while minimizing traction on the tumor. Intraoperatively, the right spermatic cord vessels appeared tortuous and mildly thickened; no suspicious intra-abdominal or inguinal lymphadenopathy or metastases were noted (Figure 3A). Through a transverse scrotal incision, the enlarged right testis (approximately 4.0 cm × 3.0 cm × 3.0 cm) was dissected along the capsule; adhesions consistent with prior surgery were present. To minimize the risk of tumor cell dissemination, the specimen was handled gently without compression (Figure 3B). The spermatic cord was mobilized to the internal ring and ligated in multiple layers at a high level (Figure 3C). The resected specimen had an intact capsule and an unremarkable cord stump (Figure 3D). On sectioning, the testis showed a pale yellow, fish-flesh-like appearance without identifiable residual normal testicular tissue (Figure 3E). Frozen-section assessment supported malignancy; the spermatic cord margin and peritumoral fat were negative. The spermatic cord margin and surrounding tissues were confirmed to be free of tumor involvement on intraoperative frozen examination.

Figure 3 Intraoperative findings and surgical specimen. (A) Laparoscopic view showing no visible intra-abdominal metastatic lesions, normal-appearing spermatic vessels without significant thickening, and no enlarged lymph nodes at the internal inguinal ring. (B,C) After laparoscopic high ligation of the spermatic cord at the internal inguinal ring, the testis was delivered through a scrotal incision with gentle dissection along the previous surgical scar to minimize tumor manipulation. (D) Resected specimen showing an intact capsule and unremarkable cord stump. (E) Gross section demonstrating pale yellow, fish-flesh-like tumor tissue without identifiable residual normal testis.

Final histopathology demonstrated a yolk sac tumor with reticular, microcystic, alveolar, and papillary patterns, with necrotic areas (Figure 4A-4C). Schiller–Duval bodies and hyaline globules were focally observed (Figure 4D). Lymphovascular tumor thrombi were present (Figure 4E). Resection margins of the spermatic cord and vas deferens were negative. Immunohistochemistry showed AFP(focal+), SALL4(+), Glypican-3(focal+), OCT4(−), cytokeratin(+), CD34(+), CD99(+), S-100(−), Ki-67(hotspot ~95%+), CD117(+), CD30(−), and CD68(−) (Figure 4F-4O).

Figure 4 Histopathology and immunohistochemistry. (A-C) Yolk sac tumor with reticular/microcystic and papillary patterns and necrotic areas (H&E). (D) Schiller-Duval body and hyaline globules (H&E). (E) Lymphovascular tumor thrombus (H&E). (F-O) Immunoprofile supporting yolk sac tumor [AFP(focal+), SALL4(+), Glypican-3(focal+), OCT4(−), Ki-67(hotspot ~95%+)]. AFP, alpha-fetoprotein; H&E, hematoxylin and eosin.

AFP decreased to 397.1 ng/mL at postoperative week 1 (>50% reduction) and normalized to 9.39 ng/mL by postoperative day 17. The patient received adjuvant chemotherapy in the oncology department. At 3 months postoperatively, ultrasound showed no residual or recurrent mass in the right inguinal or scrotal region, and the incision healed well.

All procedures performed in this study were in accordance with the Declaration of Helsinki and its subsequent amendments. This study was approved by the ethics committee of Kunming Children’s Hospital (No. 2025-05-129-K01). Written informed consent was obtained from the patient’s parents for the publication of this case report and accompanying images. A copy of the written consent is available for review by the editorial office of this journal.

Discussion

Cryptorchid testicular torsion is uncommon but demands a high index of suspicion, as the testis may be located in the inguinal canal or abdomen and classic scrotal signs can be absent (5,6). Even when detorsion is achieved and the testis is preserved, long-term outcomes are variable; atrophy and impaired function are not rare after pediatric torsion, and salvage rates in cryptorchid torsion remain suboptimal in many series (7,8). Separately, cryptorchidism is a recognized risk factor for testicular germ-cell tumors. Although earlier orchiopexy may reduce this risk, it does not eliminate it (9-11). Against this background, our case raises a clinically important question: how should clinicians interpret postoperative imaging changes after testis-sparing detorsion in a child with cryptorchidism?

A practical pitfall is that heterogeneous testicular echogenicity on follow-up ultrasound is frequently attributed to post-ischemic edema, hemorrhage, and subsequent fibrotic remodeling after detorsion, rather than malignancy (7). For most patients, this explanation is appropriate. However, when cryptorchidism coexists, reassurance based solely on restored blood flow may be misleading. In our patient, imaging appeared relatively stable for several months after detorsion, yet a progressively enlarging scrotal mass emerged around 6 months postoperatively, accompanied by a markedly elevated AFP, ultimately confirming a yolk sac tumor. This timeline underscores that follow-up should not be restricted to reperfusion alone; clinicians should also assess whether sonographic morphology evolves from diffuse heterogeneity toward a definable solid nodule or mass, or whether vascularity becomes focally or diffusely increased beyond expected post-torsion patterns (12-15). When such evolution is observed, escalation to tumor markers and cross-sectional imaging is warranted (13,16).

At present, there is no evidence establishing a causal relationship between detorsion/reperfusion and tumorigenesis. Nonetheless, several biologically plausible hypotheses merit consideration. Cryptorchid testes may exhibit disturbed germ-cell maturation and increased genomic instability, providing a permissive substrate for malignant transformation (9,10). Superimposed ischemia-reperfusion may induce oxidative stress and DNA damage, and tissue repair involves angiogenesis and extracellular-matrix remodeling, which could theoretically favor clonal expansion in a susceptible microenvironment (7,8). These concepts remain speculative and should be framed as such.

Importantly, the tumor in this patient may have been pre-existing but clinically occult at the time of torsion, and the acute ischemic event may have merely unmasked an underlying malignancy during follow-up. Current evidence does not allow differentiation between a previously existing tumor and de novo malignant transformation occurring after detorsion. Therefore, the temporal association observed in this case should not be interpreted as evidence of causality.

From a management perspective, emergency detorsion remains the priority. However, perioperative oncologic risk stratification should not be ignored, particularly in cryptorchid torsion where the differential diagnosis can include tumor-related torsion or an occult malignancy. Serum AFP and β-hCG are minimally invasive and repeatable. In prepubertal boys, AFP is especially informative for yolk sac tumors, although interpretation must account for age-related physiological variation (13). Tumor marker evaluation in our patient demonstrated markedly elevated AFP with normal β-hCG levels, a pattern typical of prepubertal yolk sac tumors and supportive of the final diagnosis. Importantly, AFP testing should not be reflexively triggered by any postoperative echogenic heterogeneity. A more defensible approach is selective testing guided by risk stratification: progressive enlargement, emergence of a discrete solid lesion, or unexpectedly increased vascularity should prompt tumor markers and further imaging (MRI/CT) without delay (12,14-16). In our view, obtaining baseline AFP and β-hCG at presentation may be considered in selected cases of cryptorchid torsion-particularly when patients present at an older age, when preoperative imaging demonstrates atypical or mass-like features, or when intraoperative findings raise suspicion for underlying pathology. Importantly, tumor marker assessment must not delay emergency detorsion, which remains the highest priority. We do not advocate routine tumor marker testing for all cases of testicular torsion; rather, a risk-adapted approach is more appropriate (16).

Intraoperatively, when the testicular parenchyma appears suspicious (unusual firmness, nodularity, or mass-like change), frozen-section assessment can provide timely histologic guidance and help balance organ preservation against oncologic control (17). Given that benign lesions are proportionally more common in prepubertal testes than in adults, organ-sparing strategies can be considered when supported by tumor markers, intraoperative pathology, and a structured follow-up plan, but oncologic safety must remain paramount (18). Particularly in cryptorchid testes and in very young children, a low threshold for radical orchiectomy is appropriate when intraoperative findings, tumor markers, or imaging raise concern for malignancy.

We acknowledge that inguinal radical orchiectomy with high ligation of the spermatic cord represents the standard oncological approach for suspected malignant testicular tumors. In this case, the use of a scrotal incision represented a deviation from conventional practice and was influenced by patient-specific factors, including prior surgery-related adhesions and tumor location predominantly within the scrotum. However, high ligation of the spermatic cord was achieved at the internal inguinal ring under laparoscopic guidance, and intraoperative frozen-section evaluation confirmed negative margins. We recognize that transscrotal handling may carry theoretical oncological risks, and this aspect should be considered a limitation rather than a recommended strategy.

In addition, this case highlights the importance of individualized management and comprehensive parental counselling in pediatric patients with rare and complex conditions. Families should be informed not only about the risk of testicular atrophy following detorsion but also about the persistent oncologic risk associated with cryptorchidism, which may remain even after orchiopexy. In uncommon clinical scenarios such as cryptorchid torsion with subsequent tumor development, shared decision-making becomes particularly important to balance organ preservation, oncologic safety, and long-term surveillance strategies. Tailored diagnostic and therapeutic approaches based on patient-specific factors, including prior surgical history, imaging characteristics, and intraoperative findings, may contribute to optimal outcomes. Similar principles of individualized management have been emphasized in rare pediatric surgical conditions, where multidisciplinary assessment and family engagement play central roles in clinical decision-making (19,20). These considerations further support the need for careful perioperative risk assessment and structured follow-up in children with atypical presentations.

Based on this experience, a structured postoperative surveillance strategy may be helpful for salvaged cryptorchid testes after torsion. Early ultrasound follow-up is recommended to assess reperfusion and parenchymal evolution, typically within the first month after surgery, followed by periodic reassessment (e.g., at 3–6 months). Expected post-ischemic findings include diffuse heterogeneous echogenicity, transient edema, and gradual volume reduction. However, certain features should prompt escalation of evaluation, including progressive enlargement, emergence of a discrete solid lesion, focal or diffuse hypervascularity beyond expected reperfusion patterns, or persistently abnormal morphology. In such situations, repeat tumor marker assessment and cross-sectional imaging (MRI or CT) should be considered, and surgical re-exploration may be warranted if malignancy cannot be excluded. A summary of suggested postoperative surveillance considerations is provided in Table 1.

In summary, cryptorchid testicular torsion carries both an acute risk of organ loss and a long-term oncologic context. Post-detorsion heterogeneous echogenicity should be interpreted dynamically. In children with cryptorchidism, clinicians should integrate morphologic evolution on ultrasound with AFP trends and timely cross-sectional imaging when indicated, to minimize the chance of overlooking a rare but high-impact malignancy. No evidence of recurrence or metastasis has been detected during follow-up to date. However, the relatively short follow-up period represents a limitation of this report, and longer surveillance is necessary to fully assess long-term oncological outcomes.

Conclusions

This case highlights that malignancy may become clinically apparent during follow-up after testis-sparing detorsion of a cryptorchid testis. Postoperative surveillance in this setting should assess not only reperfusion, but also dynamic morphologic evolution. Progressive enlargement, development of a definable solid lesion, or atypical vascularity should prompt timely tumor marker evaluation and further imaging to avoid delayed diagnosis.

Acknowledgments

None.

Footnote

Reporting Checklist: The authors have completed the CARE reporting checklist. Available at https://tau.amegroups.com/article/view/10.21037/tau-2026-1-0009/rc

Peer Review File: Available at https://tau.amegroups.com/article/view/10.21037/tau-2026-1-0009/prf

Funding: This study was supported by Science and Technology Project of Kunming Municipal Commission of Health and Construction (Nos. 2024-SW(L)-07, 2025-04-05-015, 2025-SW(T)-01), Kunming Medical Joint Project of Yunnan Science and Technology Department (Nos. 202001AY070001-271, 202301AY070001-108), Research Project of Yunnan Provincial Clinical Medical Center (Nos. 2024YNLCYXZX0430, 2024YNLCYXZX0428), Medical reserve talents of Yunnan Province (No. H-2025004) and Scientific research project of Yunnan Clinical Medical Center. The funding bodies played no role in the study’s design and collection, data analysis and interpretation, and manuscript writing.

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://tau.amegroups.com/article/view/10.21037/tau-2026-1-0009/coif). The authors have no conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. All procedures performed in this study were in accordance with the Declaration of Helsinki and its subsequent amendments. This study was approved by the ethics committee of Kunming Children’s Hospital (No. 2025-05-129-K01). Written informed consent was obtained from the patient’s parents for the publication of this case report and accompanying images. A copy of the written consent is available for review by the editorial office of this journal.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

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