Microscopic description:

The respresentative section of testicular parenchyma revealed a fibrotic area, having characteristics of a regressed germ cell tumor with no viable tumor identified. Negative immunostains: SALL4, OCT ¾, AE1/AE3.

Multiple immunostains were performed to assess the neoplastic process seen in the B1 lymph node. At surface level, CD45 presents as positive. However, at higher magnification it is shown to have nests of neoplastic cells that are unreactive. These large atypical neoplastic cells present with enlarged nuclei and pronounced nucleoli. Occasional multinucleations can be observed as well. These neoplastic cells have shown positivity for OCT ¾, PLAP, SALL4, CD117, and D2-40.

Given the IHC reactivity and microscopic characteristics, the testicular tumor with lymph node involvement has shown qualities that are consistent with the diagnosis of metastatic seminoma.

Discussion:

Testicular seminoma accounts for approximately 50% of all GCT cases and mostly affects men ages 15-40 years. The breakdown of occurrence for the two most common stages, stage I (restricted only to testis) and stage II (lymphadenopathy of the infradiaphragmatic region), shows ~80%  and ~20% of testicular seminoma cases, respectively.

Revealing a solid palpable mass shown via imaging with reports of no testicular pain is a classic presentation of testicular seminoma. If presenting with metastasis to the retroperitoneal lymph nodes, having complaints of back and abdominal pain as well as systemic symptoms are commonly seen. Checking the serum tumor markers, if a germ cell tumor is suspected, could reveal elevated levels of AFP, HCG, and LDH. 

Gross examination generally reveals a well-circumscribed mass that is pale yellow, solid, with fleshy cut surfaces; areas of necrosis and hemorrhage are not uncommon. Microscopic examination shows sheets and/or nests of monotonous cells frequently seen separated by fibrous septa. Cytoplasm is seen as clear to eosinophilic, and nuclei are large with distinct nucleoi. Seminoma displays reactivity to IHC stains such as CD117, OCT3/4, SOX17, SALL4, and D2-40.

Testicular seminoma is relatively curable, approaching a cure rate of 100% in stage I and over 80% in metastatic cases. Radical orchiectomy serves as the primary component of treatment, followed by chemo and/or radiation therapy depending on the staging and risk assessment of the results.

References:

Dong, W., Gang, W., Liu, M., & Zhang, H. (2015). Analysis of the prognosis of patients with testicular seminoma. Oncology Letters, 11(2), 1361-1366. doi:10.3892/ol.2015.4065

Marko, J., Wolfman, D. J., Aubin, A. L., & Sesterhenn, I. A. (2017). Testicular Seminoma and Its Mimics: From the Radiologic Pathology archives. RadioGraphics, 37(4), 1085-1098. doi:10.1148/rg.2017160164

Oldenburg, J., Fosså, S., Nuver, J., Heidenreich, A., Schmoll, H., Bokemeyer, C., Kataja, V. (2013). Testicular seminoma and non-seminoma: ESMO Clinical Practice Guidelines for diagnosis, treatment and follow-up. Annals of Oncology, 24, Vi125-Vi132. doi:10.1093/annonc/mdt304

Testicular cancer. (2019, January 31). Retrieved March 07, 2021, from https://rarediseases.org/rare-diseases/testicular-cancer/

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