Discussion
Metastasis of gastrointestinal tumors to the testes is a rare occurrence, and the identification of the primary site can pose a significant challenge in diagnosis and treatment planning [3]. This is a rare case of a 44-year-old male with signet-ring cell mucinous adenocarcinoma metastasis in the right testis, possibly originating from the small intestine. Notably, the metastasis in the testis was the only clinical manifestation observed, making this presentation uncommon.
Tumors can spread to the testis through various pathways, including hematogenous dissemination, retrograde migration through the lymphatic system, retrograde extension along the spermatic cord, and seeding of peritoneal surfaces, including the tunica vaginalis. [1] Subsequently, Tumor cells may migrate through the abdominal ring and over the open Haller’s habenula to reach the testis, mimicking the pattern of migration seen in Krukenberg tumor in women. [1]
Nonetheless, the incidence of secondary metastasis to the testis is relatively low, which may be attributed to its unique anatomical features. The testes are situated in the scrotum, supported by scrotal tissue and spermatic cords. The serosal tunica vaginalis invaginates the testes, becoming separated from the processus vaginalis and peritoneal cavity just before birth. [1] Additionally, the relatively low temperature of the scrotum creates an unfavorable environment for metastatic tumor cells to survive, which explains the rarity of testicular metastases. [1]
Signet-ring cell carcinoma (SRCC) is a rare subtype of adenocarcinoma characterized by the presence of cells with abundant intracytoplasmic mucin, displacing the nuclei to the periphery. Although SRCC is more commonly associated with gastric cancer, it has been reported in other organs, including the small intestine. The prognosis for patients with SRCC in the small intestines is generally poor, with a five-year survival rate of 16.1%. [4] Early detection and appropriate treatment are essential in improving patient outcomes.
The patient’s history of heavy smoking may have contributed to the development of the metastasis. The lack of significant past medical, surgical, or family history suggests that the patient was not at high risk for testicular cancer or metastatic disease. However, the patient’s smoking history may have increased the risk of developing cancer and contributed to the development of this metastatic disease.[5]
Based on the physical findings of a painless, firm, and irregular mass arising from the testicle, a testicular tumor was suspected, and a radical orchiectomy of the right testes was deemed necessary for effective management of the patient’s condition. [6] Despite the normal levels of AFP, LDH, and HCG, the possibility of a stromal tumor could not be ruled out. The procedure made the pathological diagnosis and staging possible, thereby aiding in the determination of the appropriate course of action.
While the imaging findings initially provided evidence of a primary testicular cancer with metastasis. The ultimate identification of the primary site of origin was achieved through the use of immunohistochemical markers. Specifically, positive staining for CK7, CK20, and CDX2 strongly suggested a gastrointestinal origin, with the stomach or small intestine being the most likely source. [7] This highlights the critical role that immunohistochemistry plays in determining the primary site of origin in metastatic tumors, especially in cases where imaging studies are inconclusive. Furthermore, upper and lower endoscopies with biopsies from the stomach and colon were performed to identify the primary site, but no abnormalities were detected. The lack of equipment to visualize the small intestine limited the ability to confirm the suspicion of the small intestine as the primary site.
Once gastric SRCC was ruled out and an intestinal primary carcinoma is suspected, FOLFOX might be a proper treatment option. As it is used for surgically unresectable metastatic colorectal cancers and has shown activity in small intestinal adenocarcinomas. [8]
Unfortunately, the rarity of SRCC of the small intestine, and the lack of clinical trials made it difficult to evaluate the effectiveness of the chosen therapy, further emphasizing the uncertainty surrounding the optimal treatment for this type of cancer.