Seminoma is a germinoma of the testis. It is one type of testicular cancer that's believed to originate from the germinal epithelium of the seminiferous tubules. Presentation They produce bulky masses that can be up to ten times the size of a normal testis. They are painless and don't transilluminate. Diagnosis POU2AF1 and PROM1 have been proposed as possible markers. Peak incidence occurs in the 4th decade of life. Histology shows large cells, clear cytoplasm, distinct cell membranes, and sept… (More on Seminoma)