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In all, 11 patients met our inclusion criteria (mean age 37 months, range 9 days to 144 months). Seven patients presented with a painless testicular mass, three presented with an inguinal hernia/communicating hydrocele, and one presented with an undescended testicle. Scrotal US was used in seven patients and showed abnormal intraparenchymal lesions in all seven (Table 1). Further review yielded almost identical findings in three patients, in which they had multiple hyper- and hypoechoic structures, septated cysts, and areas with acoustic shadowing associated with potential internal calcifications. Two patients had similar US findings, with homogenous, non-cystic lesions. One patient had a solitary intratesticular cystic lesion with no other associated abnormalities. The final patient had a very large intratesticular mass that was heterogeneous, but void of cystic structures.
Table 1. Summary of scrotal US and histopathological findings
|Heterogeneous, cystic, hyper- and hypoechoic regions||3|
|Homogenous, no cystic changes||2|
|Solitary intratesticular cystic lesion||1|
|Heterogeneous, no cystic changes||1|
|Yolk sac tumour||2|
Tumour markers (α-fetoprotein and β-hCG) were obtained in eight patients, with significant α-fetoprotein elevations in three. All three patients with elevated α-fetoprotein levels normalized after orchidectomy. CT of the chest, abdomen, and pelvis in eight patients showed extensive metastatic disease, with mediastinal adenopathy in one. All patients were treated with radical inguinal orchidectomy based on the surgeons’ preference. Pathology revealed four teratomas, two yolk sac tumours, two epidermoid cysts, one extrarenal nephroblastomatosis, and two paratesticular rhabdomyosarcomas (Table 1). Chemotherapy was administered to the patients with rhabdomyosarcoma. No patients were treated with external beam radiation or retroperitoneal lymph node dissection. The mean (range) follow-up was 20.3 (1–74) months. The overall survival rate was 10 of 11 patients, with one patient dying from metastatic rhabdomyosarcoma.
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Yolk sac tumour has been reported as the most common primary prepubertal testis tumour. A review of the AAP PTTR revealed that these tumours accounted for 62% of all recorded cases . However, recent single-institutional reports yielded the opposite information, with a preponderance of the lesions favouring benign testis pathology over malignant lesions. Metcalfe et al.  reported on 51 primary testicular lesions, of which 43% were teratoma and only 8% were yolk sac tumours. Pohl et al.  pooled data from four participating institutions for all primary testicular tumours in boys aged ≤ 12 years, identifying teratoma in half of the cases, with yolk sac tumour comprising only 15%. In addition, Shukla et al.  evaluated 77 primary testicular lesions, and of the 43 germ cell tumours, 51.5% were teratomas and 23.2% yolk sac tumours. The present data parallels these recent reports, in that four of 11 patients had teratomas while two had yolk sac tumours. The data presented by the AAP PTTR is extremely important, but a reporting bias with under-representation of benign tumours might exist, explaining the differences between the results of large collection registries vs those from single institutions. The benefit of single-institution studies is that all pathology, benign or malignant, can be tracked and analysed in a similar fashion, thus minimizing reporting bias. By contrast, the disadvantage of single-institutional studies is the few patients available for analysis.
In the past, the management of prepubertal testis tumours was based on experience with adult testis cancer. Many clinicians would agree that prepubertal testicular neoplasms differ greatly from postpubertal lesions. Prepubertal testicular and paratesticular tumours account for only 1–2% of all paediatric solid tumours, with an incidence of 0.5 per 100 000 in children . By contrast, testicular tumours are 10 times more frequent in postpubertal males than in boys aged ≤12 years, with a reported incidence of 5.4 per 100 000 adults [9,10]. Histologically, Weissbach et al.  reported findings from the Bonn Registry, in which 89% of adult tumours were seminomas, embryonal carcinomas or nonseminomatous mixed germ cell tumours, compared to only 9% in children. In addition, 60% of adult testis tumours contain mixed histology. Conversely, Kay et al.  reported that 98% of malignant germ cell tumours in prepubertal testes have pure yolk sac histology, with the vast majority of prepubertal testis tumours containing only one histological type. These differences in histological subtypes could also account for the differences in natural history, with metastases occurring in 61% of adults but only 9% of children .
Based on these pathological characteristics, testis-sparing surgery has been reported for several prepubertal tumours. In 1984 Weissbach et al.  reported on two patients with teratoma successfully treated with testis-sparing enucleation. A report of 17 patients treated with partial orchidectomy for teratomas showed no evidence of recurrence or testicular atrophy after a mean follow-up of 10 years . Rushton et al.  provided important pathological data on five teratoma specimens and ascertained the safety of the testicular-sparing approach. In another series of testis-sparing surgery in 13 prepubertal boys with the final diagnosis of either teratoma or epidermoid cysts, no patient had recurrent tumour in the ipsilateral or contralateral testis after a mean follow-up of 88 months . In addition, they reported no evidence of testicular atrophy or persistent orchalgia. Despite most of the tumours in the present series being benign, no testis-sparing approach was used. This was probably the result of surgeon preference or anatomical limitations, as we advocate this approach when appropriate.
Although the decision to perform a partial orchidectomy primarily depends on intraoperative findings, an appropriate preoperative assessment might assist with the final decision. Any patient with normal preoperative α-fetoprotein levels and US that reveals salvageable testis tissue should be considered for a testis-sparing approach. Preoperative elevated serum α-fetoprotein levels further differentiate yolk sac tumours from other tumours. In addition, at least 93% of yolk sac tumours stain positively for α-fetoprotein. Ross et al.  suggested a testis-sparing treatment algorithm for prepubertal children with a normal serum α-fetoprotein level, but excluded infants aged 6–12 months and with an α-fetoprotein >100 ng/mL, and those aged >1 year with an α-fetoprotein level greater than the normal adult range.
Although there are no reliable US criteria for diagnosing benign vs malignant testis lesions, teratomas usually appear cystic, septated with intervening solid components, as well as acoustic shadows associated with potential internal calcifications. Metcalf et al.  reported 13 preoperative US findings suggestive of benign disease, that were confirmed in all 13 cases to be benign teratomas on final histology. Our data paralleled these findings, in which the three patients who had heterogeneous, hyper- and hypoechoic areas, with cystic structures, all had benign teratomas on final pathology. The two patients with homogenous non-cystic lesions both had yolk sac tumours. The one patient with a solitary intratesticular cystic lesion had an epidermoid cyst and the final patient with a large heterogeneous non-cystic lesion had a rhabdomyosarcoma.
It is important to adhere to basic surgical principles before a partial orchidectomy. Briefly, testis-sparing surgery should be done through an inguinal incision, with complete vascular control of the cord structures. Four patients in the present series did not present with a testis mass and therefore in these cases vascular control should be obtained immediately upon suspicion of an intratesticular process. The testis should then be delivered through the incision and the mass excised for frozen-section analysis. If this shows teratoma and the patient is peri-pubertal, further frozen-sections of surrounding normal testis tissue should be analysed, because the identification of pubertal changes necessitates orchidectomy, as postpubertal teratomas can be malignant.
In the present series, we included paratesticular rhabdomyosarcoma because of its importance in the differential diagnosis of a scrotal mass and potential for intratesticular extension . Excluding these patients from this analysis would have resulted in seven benign lesions vs two yolk sac lesions.
In conclusion, we recognize the limitations with so few patients, but our findings parallel those of other recent single-institutional reports, suggesting that benign primary prepubertal testis tumours predominate over malignant lesions. The most common primary prepubertal testis tumour presenting at our institution was teratoma. All tumours should be initially approached as malignant, irrespective of certain preoperative variables that suggest a benign nature. Testis-sparing surgery is appropriate in the right patient; however, if there is any doubt, then radical orchidectomy is indicated.