Recent developments in testicular cancer from International Journal of Surgical Pathology
By Sean R. Williamson, MD
April is testicular cancer awareness month. In the Sage Journal International Journal of Surgical Pathology (IJSP), several recent publications have highlighted less common forms of testicular cancer, as well as benign tumors that may mimic testicular cancer. Although testicular cancer is overall rare, the most common form, often occurring in young to middle-aged men, is the group of tumors known as germ cell tumors (typical types being seminoma, embryonal carcinoma, yolk sac tumor, choriocarcinoma, and teratoma). The following several articles highlight rarer forms of testicular tumors.
One recent article in IJSP presents an example of myoid gonadal stromal tumor. Although most testicular cancers are germ cell tumors, which are thought to resemble the germ cells that develop into sperm (in men, or eggs/oocytes in women), rarer testicular tumors are referred to as “sex cord stromal tumors,” which resemble the supportive cells that provide the scaffolding for development of the germ cells and produce hormones, among other functions. Myoid gonadal stromal tumor is a subtype of sex cord stromal tumor that has been increasingly recognized recently and demonstrates an unusual phenotype with positivity for both muscle and nerve markers. Behavior of myoid gonadal stromal tumor thus far appears to be benign.
In another article in IJSP, Oyedeji and colleagues describe an example of testicular vasculopathy presenting as testicular torsion (twisting of the blood supply of the testis, causing pain and death of the tissue, requiring surgical removal). Testicular vasculopathy has been recently noted to be a potential cause of testicular mass, in which it is thought that mild intermittent damage to the blood vessels does not cause the severe pain and death of the tissue seen with usual torsion; however, over time a mass of hemorrhage and dead tissue may form, creating suspicion for testicular cancer. In the report by Oyedeji and colleagues, this pattern is noted in a patient with the more classic torsion presentation, supporting the hypothesis of how this microscopic pattern develops.
Kläger and colleagues report and example of well-differentiated papillary mesothelial tumor of the testis. Rarely, mesothelioma (a cancer arising from the smooth outer covering of organs like the lung) can develop on the outer surface of the testis. Mesothelioma is best known for its occurrence in the chest, sometimes related to exposure to agents like asbestos; however, there is increasing awareness that some benign proliferations of the mesothelium can occur. Kläger and colleagues draw attention to mesothelial proliferations of the testis that are unlikely to exhibit malignant behavior.
Krishnamurthy and colleagues describe examples of adenomatoid tumors occurring around the testis. These are benign tumors composed of mesothelial cells that have a different microscopic appearance from mesothelioma. Less commonly, these tumors have substantial muscle cells admixed with them, which some have referred to as leiomyoadenomatoid tumors. In this article, the authors describe positivity for similar markers in both the mesothelial and muscle components, raising the possibility that both originate from the same cells, rather than the muscle being an entrapped bystander from the normal adjacent structures.
Fontes Dias and others describe an example of sarcomatoid spermatocytic tumor. Spermatocytic tumor is considered a germ cell tumor (formerly known as spermatocytic seminoma); however, it has a different microscopic appearance, marker pattern, and genetics from the more common malignant germ cell tumors. Therefore, it was renamed as “tumor” in the 2016 World Health Organization Classification to differentiate it from the unrelated form of testicular cancer known as seminoma. After these tumors are removed, the behavior appears to be consistently benign; however, very rarely spermatocytic tumor transitions into sarcoma, in which case it may exhibit malignant behavior. Fontes Dias et al. describe an example of such sarcomatoid change within one of these tumors, which is only rarely reported.
Patton and colleagues report and example of dedifferentiated liposarcoma of the paratesticular region (the soft tissue around the testis), with epithelioid cell features. Liposarcoma (cancer resembling fat cells) is one of the most common types of sarcoma (soft tissue cancer). A common location is the retroperitoneum (the soft tissue behind the abdominal organs). Since the testis develops inside the abdomen and descends down into the scrotum with development, the soft tissue is considered part of the retroperitoneum and thus, liposarcoma can occur around the testis as well. The example reported by Patton et al. is a unique diagnostic challenge, as the cells were epithelioid, resembling those of the more common epithelial cancers. Thus, this report helps to make diagnostic pathologists aware of the broad spectrum of patterns that can be confusing in this tumor type.
Finally, Budina and Sharma describe an example of placental site trophoblastic tumor arising from testicular cancer. Placental site trophoblastic tumor is a very rare neoplasm that usually occurs in the uterus after pregnancy. However, since germ cells can recreate many different types of tissues, a wide variety of potentially surprising tumors can develop from germ cell tumors, like this one which is usually not found in men at all.
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