Unusual testicular metastatic localization of Ewing’s sarcoma: case report

Background Ewing’s sarcoma is a rare form of bone cancer that can also affect soft tissues. In some cases, it can spread to other parts of the body, including the testicles, causing testicular metastases. To our knowledge, no testicular metastasis of Ewing’s sarcoma has been reported in the literature. Summary We report an original case of an 18-year-old patient who presented with bilateral testicular masses revealing an exceptional metastasis of metastatic bone Ewing sarcoma under chemotherapy for one year. It was difficult to diagnose synchronous bilateral testicular metastases of Ewing’s sarcoma due to the low frequency of these metastases. However, given the history of metastatic cancer, the data from the clinical examination, and the results of ultrasound, it should be considered and included in the differential diagnosis. Conclusion Despite the uncommon occurrence of secondary testicular metastasis, it should be considered in the differential diagnosis when encountering such a clinical presentation.


Background
Ewing's sarcoma is a malignant bone tumor that often develops in children and young adults [1].Although this tumor is frequently observed in bones, it can also develop in soft tissues and cause secondary locations in other parts of the body [2].Most cases reported in the literature involve primary testicular localization of Ewing's sarcoma [3].To our knowledge, there are no reported cases in the literature of secondary testicular localization of Ewing's sarcoma originating from bone.In this article, we present a case of secondary testicular localization of Ewing's sarcoma and discuss the clinical, pathophysiological, and therapeutic characteristics of this rare entity.

Case presentation
An 18-year-old patient was being treated for Ewing's sarcoma of the left iliac bone with secondary bone and lung involvement for one year under chemotherapy.He presented with testicular pain for the past two months.On physical examination, the patient's overall condition was altered and he was markedly cachectic.Examination of the external genitalia revealed slightly enlarged testicles without inflammatory signs in the area, bilateral testicular induration with moderate tenderness on palpation.An ultrasound was performed, which revealed a right testicle measuring 14.5 ml, containing four heterogeneous, round lesions with regular contours measuring 13.6 × 18.6 mm, 10.8 × 9 mm, 28.5 × 18.3 mm, and 14.5 × 13.8 mm (Fig. 1a), and a left testicle measuring 35 ml containing a heterogeneous, round lesion with regular contours occupying almost the entire testicle (Fig. 1b).Tumor marker levels were normal.Based on these findings, a secondary localization at the testicular level was strongly suspected.The patient categorically refused the recommended bilateral orchidectomy, a necessary procedure due to the extensive lesions occupying almost the entirety of his testicles.Given the impossibility of proposing a partial orchidectomy, the patient was discharged with instructions to follow up with his primary care physician and to return to the emergency department if his symptoms worsened.

Discussion
Ewing's sarcoma is a malignant bone tumor composed of small round cells with high metastatic potential.It was first described by James Ewing in 1921 as a "diffuse endothelioma of bone" [4].Metastases are most commonly observed in the lungs, bones, bone marrow, and to a lesser extent, in lymph nodes [5].Secondary testicular involvement is rare, with an incidence ranging from 0.02 to 3.6% [6][7][8][9], and bilateral metastasis occurring in up to 15% of patients [6,7].The most common primary sites, excluding lymphoma and leukemia, are the prostate, followed by the gastrointestinal tract, lungs, kidneys, and melanoma [6][7][8][9][10][11][12].The majority of these cases are diagnosed at autopsy or incidentally detected during therapeutic orchiectomy for prostate cancer.The literature indicates approximately 200 reported cases of testicular metastases originating from prostate cancer, with only 18 cases being bilateral [13].
It is also important to note that, according to Julie W. Cheng et al., five cases of primary Ewing sarcoma of the testicle have been reported in the literature, involving patients aged seventeen to forty-six.In all cases, an orchidectomy was performed initially, followed by chemotherapy, and in two cases, radiotherapy.Four cases showed good progression, while one patient died after nine months [3].
Metastases can therefore represent a diagnostic challenge due to the rarity and diversity of the potentially involved primary sites.Typically, the clinical history with a known primary tumor and a characteristic image on ultrasound leads to an immediate diagnosis [8,10,12], but this is not always the case, especially when it occurs at a young age like our patient, which is a prime age for testicular cancer [7].Furthermore, some testicular metastases can mimic the histological appearance of a primary germ cell tumor, sex cord tumor, or hematopoietic tumor [10].
The rarity of testicular metastases can be explained by the blood-testis barrier and the relatively low temperature of the scrotum.The resulting thermal difference limits metastatic dissemination to the testicles through the bloodstream [6,11].The primary cancer may spread to the testis through retrograde venous extension, arterial embolism, lymphatics, endocanalicular spread, or direct transperitoneal seeding from peritoneal carcinomatosis through the tunica vaginalis [6][7][8].
The standard treatment for Ewing's sarcoma is chemotherapy, often combined with radiation therapy and surgery to remove the primary tumor and metastases [5].Chemotherapy is administered to reduce tumor size and treat cancer cells that have spread to other parts of the body.The treatment of Ewing's sarcoma with testicular metastases depends on the severity of the disease and the extent of spread; orchidectomy may be necessary to prevent further cancer spread [11][12][13][14].Patients with Ewing's sarcoma with testicular metastases are often treated by a team of cancer specialists, including oncologists, urological surgeons, and radiotherapists, to create a personalized The low incidence of testicular metastases from any primary site does not allow for a consensus on management, nor to evaluate the prognosis or impact of this condition on survival.Ewing's sarcoma is an aggressive tumor, whose prognosis is largely determined by the metastatic or localized stage, even though therapeutic progress allows a survival rate of over 70% at 5 years in case of localized disease, and less than 30% at the metastatic stage [5].Typically, once testicular metastases are diagnosed, the prognosis is not favorable, usually indicating advanced disease [7,8,14].The long-term outcome of bilateral orchidectomy in these patients is not known, and further research is needed [11,14].

Conclusion
In conclusion, secondary testicular lesions can be diagnostically challenging due to their rarity and both clinical and morphological heterogeneity.This case demonstrates that Ewing's sarcoma can metastasize to uncommon locations such as the testes.The mechanism of spread from Ewing's sarcoma to the testes is uncertain and may vary.Typically, patients who present with these types of metastases have a poor prognosis.

Fig. 1 a
Fig. 1 a Ultrasound of the right testis, transverse view.b Ultrasound of the left testis, transverse view