Intermitochondrial cement (nuage) in a spermatocytic seminoma: comparison with classical seminoma and normal testis

The nuage, an ultrastructural marker of normal human germ cells (spermatogonia type A and primary spermatocytes), may be found associated with mitochondria (intermitochondrial cement) and/or free in the cytoplasm. Eight specimens from germ cell-related tumours were reviewed to assess whether the nuage could have diagnostic significance in testicular neoplasms. The nuage of neoplastic cells from seven classical seminomas and one spermatocytic seminoma was compared with that from two normal testes. The ultrastructural study demonstrated that only spermatocytic seminoma cells contained both types of nuage and that significantly fewer spermatocytic seminoma cells (28%) contained intermitochondrial cement compared with control spermatogonia type A (81.1%) and primary spermatocytes (47.6%). The data indicate that (1) the detection of the nuage confirms that the phenotype of spermatocytic seminoma is more differentiated than that of classical seminoma; (2) the intermitochondrial cement is an additional example of how a distinctive organelle of a normal cell is preserved in its neoplastic counterpart and (3) if the intermitochondrial cement were found in other cases of spermatocytic seminoma, this organelle of the normal germ cell lineage could be considered as a new ultrastructural marker of the neoplasm.