In the testis pure teratomas are rare, accounting for less than 7% of primary testicular tumours.1 This contrasts with the ovary, where 95% of germ cell tumours are pure teratomas.2 Teratomas do not always contain tissues representing all three germ cell layers. A monodermal teratoma is one that consists of only one germ cell layer, endoderm, mesoderm or ectoderm. The best recognised monodermal testicular teratomas are carcinoid tumours and primitive neuroectodermal tumours.3 Monodermal teratoma composed solely of cartilage is rare. We report a second case of purely cartilaginous teratoma and provide interphase cytogenetic evidence of its germ cell origin.

Case report

A 21-year-old man presented with a mass in his right testis. Blood chemistry tests showed an increased level of β-hCG (641 IU/l; normal range 0–3 IU/l), and a normal level of α-fetoprotein (2.4 ng/l; normal range 0.0–8.0 ng/l). The patient underwent orchiectomy followed by chemotherapy. Three months later, retroperitoneal lymph node dissection was done, removing a 275 g paracaval and interaortocaval mass, periaortic lymph nodes, and pericaval mass.

Methods

Immunohistochemistry

Sections 4 μm thick were cut from the paraffin block and stained with H&E. Immunohistochemistry for OCT4 was accomplished with a polyclonal goat anti-OCT4 antibody (C20, sc 8629; Santa Cruz Biotechnology, Santa Cruz, CA, USA; 1:500 dilution, 30 min at room …