Classified as Germ cell tumors & Non germ cell tumours – 90% are germ cell tumors. Consider the serum marker levels HCG, AFP.
Germ cell tumours are seminomatous and non seminomatous. Age is important when considering the differential. As a mneumonic it is said Seminomas occur is Sergeants (30-45) and teratomas in troops (20-35) age group.
Seminomas on macro show a creamy white homogenous appearance (an important differential when faced with this macro appearance is lymphoma). Micro on low power there is a monotonous diffuse often solid growth pattern. On high power the cells are evenly spaced with pale to clear cytoplasm, well defined cell borders, square boxed off nuclei with no overlapping and prominent nucleoli. There are fibrous septa and a scattered lymphocyte infiltrate. Variants include seminoma with an interstitial growth pattern which may be very subtle but on low power will appear as a area of vaguely increased cellularity but when viewed at higher power the tumour cells between the seminiferous tubules will be seen. Also seminoma with syncytiotrophoblasts – these appear as mulberry like multinucleated cells scattered in a multifocal pattern close to capillaries and should not be diagnosed as choriocarcinoma. With choriocarcinoma the hcg levels will be in the 1000s. Hcg will also be raised in seminoma and embryonal carcinoma but not to that extent. Anaplastic seminoma is described as a variant but is contraversial. Seminoma is Oct 3/4, PLAP and CD117 positive.
Regressed Germ cell tumor
When there are fibrous scars where the architecture of the seminoferous tubules appear to be retained consider a regressed germ cell tumour particularly seminoma. Look for evidence of residual seminoma or ITGCN – intratubular germ cell neoplasia. In such a case were regression is suspected it is important to put the entirety of the lesion through. The differential diagnosis would include infarction in which ghost outlines of the seminiferous tubules are identifiable. Important to correlate with the history ?torsion, ?vasculitis, tumour markers and there is no evidence of ITGCN. Regression can occur in embryonal carcinoma or teratoma.
Occurs in the 20-30s age group and is more aggressive than seminomas. On macro may have a variable appearance with foci of haemorrhage and necrosis. On micro the tumor has a variable appearance with a papillary or glandular architecture. There are ugly cells with pleomorphism. There are clefted and indented nuclei with chromatin clumping and overlapping of nuclei. There maybe smudge cells/applique pattern at the periphery which represents degenerate cells and should not be mistaken for choriocarcinoma. CD30, Oct3/4, EMA positive. CD117 neg. DD to be aware of includes anaplastic large cell lymphoma.
Yolk sac tumor
Suspect if AFP is raised. Many patterns – reticular, microcystic, endodermal sinus pattern, macrocystic, papillary, glandular and hepatoid. Stroma may be myxoid, solid or blastema like cells. Characteristically show Schiller Duval bodies – a papillary core with a blood vessel ringed by epithelium in a cystic space lined by flat cells and Hyaline globules in cytoplasms. Positive for AE1/3 and AFP. Also glycipan 3.
Early dissemination therefore generally present with metastasis. Hcg in 1000s. Haemorrhagic mass grossly. Biphasic pattern – syncytiotrophoblast and cytotrophoblast with well defined cytoplasmic borders and mononuclear cells present. hcg positive in synctiotrophoblasts, mononuclear cells positive for cytokeratin – CK7, 8, 18, 19, EMA.
May show mature, immature blastema or neuroepithelium. All postpubertal teratomas are considered malignant. Prepubertal teratomas are benign. There may be sarcomatoid transformation, also malignant transformation of mature components very rarely. The differential diagnosis includes an epidermoid cyst and a dermoid cyst which does not show ITGCN. Important to sample the specimen well and if necessary put the testis through in its entirety.
Non germ cell tumours (Sex-Cord-Stromal tumors) include sertoli cell and leydig cell tumors.
Sertoli cell tumour
Characterised by tubules or chords of cells with large eosinophilic cells with large vesicular nuclei. Tumour markers negative. S100, Ck variable, calretinin and inhibin positivity.
Leydig cell tumor
Polygonal eosinophilic cells with a syncytial pattern with a round nucleus. Characteristically rod shaped crystalloids of Reinke seen. Endocrine manifestations such as gynaecomastia and precocious puberty. Inhibin positive. Focal cytokeratin positivity.
In elderly patients spermatocytic seminoma, lymphoma and metastases more common.
Arises from spermatogonia B. So different tumourgenesis pathway to other germcell tumours which have ITGCN as a precursor. Older age group but 1/3 can occur in the seminoma age group. Diffuse pattern, oedematous with eosinophilic to basophilic fluid, macrocysts. Tri-lineage population – mononuclear cells, cells with plasmacytoid appearance and spiream cells. All germ cell markers – Oct 3/4, PLAP, CD30 neg. variable CD117 positivity. PASD neg. Can rarely show sarcomatoid transformation.
N.B. When spindle cell areas are seen in a testicular tumor consider teratoma with sarcomatoid transformation or spermatocytic seminoma with sarcomatoid transformation.
Most common- diffuse large B cell NHL. Lymphoma can be intertubular.
Tubercular like epididymo-orchitis following bcg therapy
References:Chaudri, Testicular tumours teaching seminar
Robbins and Cotran. Pathologic Basis of Disease
Boswick. Urological Pathology