Clinical history: 67 year old male with a slow-growing testicular mass.
What is the most probable diagnosis?
Though related by name to seminoma, spermatocytic seminoma is a distinctive tumour both clinically and histologically. Spermatocytic seminoma is an uncommon tumour, representing 1% to 2% of all testicular germ cell neoplasms. The age of involvement is much later than for most testicular tumours: Affected indifviduals are generally over the age of 65. In contrast to classic seminoma, it is a slow-growing tumour that does not produce metastases, and hence the prognosis is excellent. In contrast to typical seminomas, speramtocytic seminomas lack lymphocytes, granulomas, syncitiotrophoblasts, extra-testicular sites of origin, admixture with other germ cell tumours, and association with intratubular germ cell neoplasia.
Grossly, spermatocytic seminoma tends to have a soft, pale grey, cut surface that sometimes reveal mucoid cysts. Spermatocytic seminomas contain three cell populations, all intermixed: (1) medium-sized cells, the most numerous, containing a round nucleus and eosinophilic cytoplasm; (2) smaller cells with a narrow rim of eosinophilic cytoplasm resembling secondary spearmatocytes; and (3) scattered giant cells, either uninucleate or multinucleate. The chromatin in some intermediate-sized cells is similar tot htat seen in the meiotic phase of non-neoplastic spermatocytes (spireme chromatin)