American Urological Association - Classic Seminoma
- Most common type of GCT (50%).
- Peak in 30's, almost never occur in infants.
- Morphologically identical tumor in ovary is called "dysgerminoma".
- Gross: typically well-circumscribed with homogenous, gray-white, lobulated cut surface and usually NO necrosis or hemorrhages (mean 5.0 cm).
- Uniform tumor cells with abundant clear cytoplasm, distinct cell border, and large central nuclei with prominent 1-2 nucleoli (image A), (image B), & (image C).
- Separated into nests by fibrous septa.
- Lymphocytic and plasmacytic infiltrates in fibrous septa.
- Multinucleated giant cells (syncytiotrophoblasts) may be seen, especially in patients with elevated HCG.
- Granulomatous inflammation can occur in ~1/3 and when extensive may cause problems in diagnosis.
- Immunohistochemistry: PLAP+, Oct3/4+ and CD117+ (image D), and keratin-.
- Excellent prognosis with >95% cure rate for stage I and II.
- Main differential diagnosis: (other GCTs that can have solid growth)
- Embryonal carcinoma: exhibits cellular pleomorphism and nuclear overlap, CD30+ and keratin+.
- Solid yolk sac tumor: other patterns of yolk sac present, AFP+ and glypican-3+.
- Spermatocytic seminoma: older patients, with polymorphic cells (3 cell types), Oct3/4- and PLAP-.