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.