Seminoma

Histological features

•    Sheets of uniform cells divided into poorly demarcated lobules by delicate fibrous septae

•    Cells are large and round to polyhedral, with a distinct cell membrane

•    Cytoplasm is clear or watery-appearing; the nucleus is large and central with one or two prominent nucleoli

•    Septae are usually infiltrated by T-lymphocytes and may also bear prominent granulomas; 15% of seminomas contain syncytiotrophoblasts

Pattern of spread, staging and associated prognosis

•    Seminomas tend to remain localized for long periods of time (hence 70% present at Stage I disease)

•    Spread is generally via lymphatics with retroperitoneal para-aortic node involvement.  Subsequently, mediastinal and supraclavicular nodes are involved.

•    Hematogenous spread occurs later with involvement of lungs, liver, brain, and bones

Seminoma Staging

o    Stage I: Tumour confined to testis, epididymis, or spermatic cord

o    Stage II: Distant spread confined to retroperitoneal nodes below the diaphragm

o    Stage III: Metastases outside the retroperitoneal nodes, or above the diaphragm

Stain that is positive in intratubular germ cell neoplasia

•    c-kit (CD117)