Editing Germ Cell Tumours (section)

== Pathology ==

=== Classification ===
* '''<span style="color:#ff0000">Pathological: GCNIS-derived vs. non-GCNIS-derived</span>[https://pubmed.ncbi.nlm.nih.gov/27747907/]'''
* '''<span style="color:#ff0000">Clinical: seminoma vs. non-seminoma GCT (NSGCT)</span>'''
** '''<span style="color:#ff0000">GCTs that contain both seminoma and NSGCT subtypes are classified as NSGCTs</span>'''
** Clinical classification is based on differences in management and outcome

=== Seminoma ===
* '''<span style="color:#ff0000">Most common type of GCT</span>'''
** '''<span style="color:#ff0000">Comprises 52-56% of all GCTs (NSGCT comprises 44-48%)</span>'''
* '''Occurs at an older average age than NSGCTs'''
**Most seminoma cases diagnosed in the 4th-5th decade of life
* '''<span style="color:#ff0000">Arises from GCNIS and is considered to be the common precursor for the other NSGCT subtypes</span>'''

=== Non-seminoma ===
* '''<span style="color:#ff0000">Subtypes (4):</span>'''
*# '''<span style="color:#ff0000">Embryonal carcinoma (EC)</span>'''
*#* '''Aggressive'''; associated with a high rate of metastasis, often in the context of normal serum tumor markers
*#* '''Most undifferentiated cell type of NSGCT''', with totipotential capacity to differentiate to other NSGCT cell types (including teratoma) within the primary tumor or at metastatic sites.
*# '''<span style="color:#ff0000">Choriocarcinoma</span>'''
*#* '''Rare'''
*#* '''Aggressive'''
*#*'''<span style="color:#ff0000">Commonly spreads by hematogenous routes</span>'''
*#*'''<span style="color:#ff0000">Typically manifests with extremely highly elevated serum hCG levels</span>'''
*# '''<span style="color:#ff0000">Yolk sac tumour</span>'''
*#* '''Almost always produce AFP but not hCG'''
*# '''<span style="color:#ff0000">Teratoma</span>'''
*#* '''<span style="color:#ff0000">Histologically benign tumors</span>'''
*#**Contain well-differentiated or incompletely differentiated elements of at least 2/3 germ cell layers: endoderm, mesoderm, and ectoderm.
*#* '''No clinical significance to the distinction between mature and immature teratomas''', and histopathologists do not typically distinguish between the two entities.
*#* '''Generally associated with normal serum tumor markers, but may cause mildly elevated AFP'''
*#* '''<span style="color:#ff0000">Resistant to chemotherapy</span>'''
*#* '''<span style="color:#ff0000">Rarely, may transform into a somatic malignancy</span> (also known as teratoma with malignant transformation) such as rhabdomyosarcoma, adenocarcinoma, or primitive neuroectodermal tumor'''

=== Spermatocytic seminoma ===
* Accounts for <1% of GCTs.
* Believed to have a different pathogenesis and separate cell of origin than classic seminoma
* '''<span style="color:#ff0000">Does not arise from GCNIS</span>, not associated with a history of cryptorchidism or bilaterally,''' does not demonstrate i(12p), and does not occur as part of mixed GCTs
* '''Benign tumor;''' almost always cured with orchiectomy