|Year : 2013 | Volume
| Issue : 2 | Page : 86-89
Primary paratesticular yolk sac tumor: A case report and review of literature
Toijam Soni Lyngdoh1, Prema Menon1, Richa Jain2, Ashim Das3
1 Department of Pediatric Surgery, Post Graduate Institute of Medical Education and Research, Chandigarh, India
2 Department of Pediatric Hemato Oncology, Post Graduate Institute of Medical Education and Research, Chandigarh, India
3 Department of Histopathology, Post Graduate Institute of Medical Education and Research, Chandigarh, India
|Date of Web Publication||21-Mar-2013|
R. No. 3103, Level 3 A, Department of Pediatric Surgery, Advanced Pediatric Center, P.G.I.M.E.R., Chandigarh 160 012, Punjab
Source of Support: None, Conflict of Interest: None
| Abstract|| |
Paratesticular germ cell tumors are extremely rare. A 12-month-old boy with yolk sac tumor involving only the paratesticular tissue is reported. Pre-operatively raised alpha fetoprotein levels fell to normal levels after high inguinal orchiectomy. This appears to be the youngest and only the 3 rd case reported in the English literature.
Keywords: Alpha fetoprotein, paratesticular tumor, primary extragonadal germ cell tumor, yolk sac tumor
|How to cite this article:|
Lyngdoh TS, Menon P, Jain R, Das A. Primary paratesticular yolk sac tumor: A case report and review of literature. J Indian Assoc Pediatr Surg 2013;18:86-9
|How to cite this URL:|
Lyngdoh TS, Menon P, Jain R, Das A. Primary paratesticular yolk sac tumor: A case report and review of literature. J Indian Assoc Pediatr Surg [serial online] 2013 [cited 2020 Jan 18];18:86-9. Available from: http://www.jiaps.com/text.asp?2013/18/2/86/109363
| Introduction|| |
Pre-pubertal testicular and paratesticular tumors represent 1-2% of all solid pediatric lesions with an incidence of 0.5-2 per 100,000 children. Paratesticular tumors account for only 15% and are mostly benign.  Malignant paratesticular tumors do arise, the most common being rhabdomyosarcoma, a non-germ cell tumor (GCT).  GCTs arising from paratesticular tissues are rare, because of which, treatment options are not standardized. Ultrasound (US) and tumor markers aid in the diagnosis and treatment planning. Correct diagnosis is usually made only from histopathological examination of the excised specimen. An infant with yolk sac paratesticular tumor who underwent high inguinal orchiectomy is reported because of its rarity.
| Case Report|| |
A 12-month-old boy presented with painless progressive swelling of the right scrotum of 1 month duration. There was no history of trauma, fever, weight loss or any constitutional symptoms. The general physical examination revealed an active playful child with normal developmental milestones. On local examination, a right scrotal mass of size 3.5 cm × 4.5 cm, non-tender, firm to hard in consistency with smooth surface and regular margin was felt just above and separately from the testes. However, mobility of the testis appeared to be restricted. Overlying skin was normal and there was no inguinal lymphadenopathy. The abdominal examination was unremarkable.
An ultrasonography (USG) revealed a large heterogeneous mass lesion in the right hemiscrotum, separately seen from the right testis. The chest radiograph was normal and computed tomography (CT) scan of the abdomen and pelvis did not reveal any retroperitoneal lymphadenopathy. There was no abnormal osteoblastic activity on bone scan. The serum alpha fetoprotein (AFP) level was found to be markedly elevated for age (555.1 ng/ml) with normal beta human chorionic gonadotrophin (HCG). Through an inguinal incision, the tumor mass (which appeared to be slightly adherent to the testes) along with the testes was delivered with an intact tunica vaginalis. The spermatic cord was found to be congested. High inguinal orchiectomy was done [Figure 1]. The gross sectioned specimen showed the paratesticular location of the tumor with normal tunica albuginea [Figure 2]. The histopathological examination revealed a tumor arranged predominantly in glandular-alveolar pattern with formation of Schiller-Duval bodies with occasional solid and papillary pattern with hyperchromatic nucleus and moderate amount of clear cytoplasm [Figure 3] suggestive of yolk sac (endodermal sinus) tumor without any other germ cell component. The testis, spermatic cord and resection margins were free of tumor.
|Figure 1: Photograph of the excised tumor following high inguinal orchiectomy with intact tunica vaginalis|
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|Figure 2: Gross sectioned specimen showing paratesticular location of the tumor with normal testis and intact tunica albuginea|
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|Figure 3: Photomicrograph of the same tumor showing glandular-alveolar pattern of tumors (straight arrows) with formation of characteristic Schiller-Duval bodies (black curved arrow)|
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At 18 months follow-up, the patient was doing well with AFP level of 5 ng/ml and no radiological evidence of metastasis.
| Discussion|| |
Paratesticular tissues consist of the epididymis, spermatic cord, vestigial remnants and fascia derived from abdominal wall during testicular descent. Unlike testicular masses, most paratesticular masses are benign.  Malignant paratesticular tumors are rare and they usually occur from 2 nd decades to 5 th decades.  Yolk sac tumors are the most common pediatric malignant extragonadal GCT. In neonates and young children, these neoplasms are found primarily in extragonadal sites, particularly the sacrococcygeal area. They are also seen in the testes of infants and young boys but rarely at paratesticular sites. To our knowledge, only two cases have been reported in the English literature earlier. , During early embryogenesis, primordial germ cells migrate and eventually get incorporated into embryonic gonadal tissue. Friedman, et al. suggested that extragonadal GCT arises when there is aberrant migration from its normal pathway or remains outside the coalescence of gonadal tissue.  It is imperative to ensure that testicular tissue is not involved in order to label the tumor as primary paratesticular.
The most common presentation is of a painless scrotal mass. However, pain may be associated when torsion of the testes or intra tumoral hemorrhage occurs which may lead to erroneous diagnosis of a benign scrotal lesion leading to scrotal approach and potential violation of onco surgical principles. US is currently the imaging modality of choice for distinguishing paratesticular from testicular masses.  However, it is often non-specific with malignant tumors mimicking the more common benign lesions and vice versa.  Addition of Doppler may help in increasing the diagnostic accuracy. Chest radiography should be performed as 20% of yolk sac tumors occur with lung metastasis. CT scan of the chest, abdomen and pelvis is mandatory if there is high suspicion of malignant GCT. However, the correct diagnosis is made only after histopathological examination, which demonstrates eosinophilic periodic acid-Schiff (PAS) positive inclusions in the cytoplasm of clear cells that consist of AFP and Schiller-Duval bodies.
Studies have also shown deletions in chromosomes 1p36 in 80-100% cases of infantile GCT arising from testicular and paratesticular sites.  Pediatric yolk sac tumors are cytogenetically and biologically distinct from their adult counterpart. They are generally diploid or tetraploid unlike those in adults which tend to have aneuploid DNA. More than 85% cases present in stage I and are predominantly of pure histology, unlike mixed GCT in adults. Serum AFP is also a reliable marker in more than 90% cases. Overall the prognosis is better in children as compared to adults. 
Tumor markers should be evaluated before surgery if malignancy is suspected pre-operatively. AFP levels are often elevated in yolk sac tumors but not beta HCG and serve as a tumor marker which after complete excision should return to normal (<20 ng/ml) within 1 month. Persistently elevated AFP levels after surgery suggest tumor metastasis or recurrence. The age of the patient should be considered while interpreting levels of tumor markers. In our patient, AFP levels were 555.1 ng/ml, which came down to 40.4 ng/ml and 12.1 ng/ml at 1 month and 3 months respectively after surgery.
The treatment for paratesticular yolk sac tumor is not standardized. Previous reports by Crain, et al.  and Shefi, et al.  are summarized in [Table 1]. No chemotherapy was given to our patient as it was a stage I disease as per staging system of the Children's Oncology Group and the National Cancer Institute. It was also not given in view of his age. High inguinal orchiectomy was justified as serum AFP was highly elevated, the testis appeared to be adherent to the tumor clinically and micrometastasis to the testis could not be ruled out pre-operatively. Spread to the retroperitoneal lymph nodes is uncommon in children so routine prophylactic dissection of the nodes is not recommended. There appears to be no role of testes sparing surgery in malignant paratesticular GCT. However, it may be considered when US shows salvageable testicular tissue in benign tumors with normal serum AFP levels. 
The risk of recurrence in imaging and pathologically proven stage I disease with normal serum AFP levels after inguinal orchiectomy is 15-22% and is greatest in the first 2 years.  Survival with modern chemotherapeutic regimen approaches 100% even in metastatic yolk sac tumor in children. Chemotherapy is indicated in patients with radiographic evidence of metastatic disease or persistently elevated serum AFP levels. Our patient has been kept under close surveillance with serum AFP estimation and chest radiograph every 3 months for the 1 st year and will be monitored 6 monthly in the 2 nd year.
| Conclusion|| |
Paratesticular yolk sac tumors are extremely rare with only two cases reported earlier. Clinical findings along with US and tumor markers help in differentiating this tumor from non-neoplastic mimics. High inguinal orchiectomy is warranted as tumor microinvasion of the testes cannot be ruled out pre-operatively, even if the testis is salvageable.
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[Figure 1], [Figure 2], [Figure 3]