Seminoma-like malignant Sertoli cell tumour of the testis

Definition

A variant of testicular Sertoli-cell tumour which closely mimics seminoma

Clinical features

Patients are adult (age range 15-80, median 37 years) who present with a testicular mass. A history of "recurrent seminoma" at the site of radiotherapy should raise the suspicion of this entity, as should a patient older than 55 with an apparent seminoma. A raised serum HCG would favour a true seminoma, but only occurs in up to 25% of patients.

Macroscopic appearances

Tumours range up to 9 cm diameter and are usually firm, white to yellow-tan with foci of haemorrhage. They may extend through the testicular hilum to involve the epididymis.

Histopathology

The tumour cells typically have clear cytoplasm, which may be vacuolated and often a distinct cell border. Some cases have cells with eosinophilic cytoplasm, which occasionally may condense to impart a rhabdoid appearance. Spindle cell areas and osteoclast-like giant cells have been reported. Nuclei are small to medium size, round to oval, and lack the squared-off edges typical of seminoma. Nucleoli may be prominent. The mitotic rate may be up to 20 per 10 HPF but is usually about 1 per 10 HPF. A PAS stain commonly demonstrates the presence of glycogen.

The tumour cells are nested or form sheets, solid tubules or cords. Hollow tubules or pseudofollicles may be present. Fibrous bands separate the tumour nests. There is usually a lymphoplasmacytic infiltrate, of varying intensity, which may form germinal centres. The infiltrate may include plasma cells or eosinophils. However, granulomatous inflammation is not seen. There may be psammomatous calcification or dystrophic calcification of the fibrotic areas.

Immunohistochemistry

Inhibin	4/4
AE1/AE3	3/6
Cam5.2	2/4
EMA	6/6
Placental alkaline phosphatase	0/5
vimentin	3/4
calretinin	1/3

Differential diagnosis

Classical seminoma:

Sertoli-cell tumour	classical seminoma
inflammatory infiltrate may include prominent plasma cells and eosinophils	inflammatory infiltrate is granulomatous in up to 50% of cases
tubule formation is more common but may require searching.	tubules may form and degeneration may render them hollow
The tubules are composed of columnar with oval nuclei, arranged perpendicular to the long axis of the tubule	tubules composed of cuboidal cells with round nuclei and prominent nucleoli
nuclei smaller and less hyperchromatic, nuclear atypia limited	marked nuclear atypia, nuclei have "squared-off" edges
usually less than 3 mitoses per 10 HPF	usually more than 10 mitoses per 10 HPF
lack intratubular germ cell neoplasia	90% of cases show intratubular germ cell neoplasia
may have a myxoid stroma	lack a myxoid stroma
may include a lipid-rich, spindle cell or osteoclastic component	do not include a lipid-rich, spindle cell or osteoclastic component
positivity for inhibin and EMA	negative for inhibin and EMA
negative for Placental alkaline phosphatase	membrane-positive for Placental alkaline phosphatase
positivity for AE1/AE3 may be strongly positive	AE1/AE3 at most focally and weakly positive
may be positive for calretinin	negative for calretinin
serum HCG normal	serum HCG raised in 10-25% of patients

Spermatocytic seminoma: there is a polymorphous population of small, medium and large cells, the later with "spireme" chromatin. Extensive sampling may be necessary in "anaplastic" spermatocytic seminoma.
solid yolk sac tumour: search for more characteristic areas. Serum AFP likely to be raised.
metastatic renal cell carcinoma: there is an intricate vasculature
metastatic melanoma

Management

Sertoli-cell tumours are resistant to radiotherapy and chemotherapy. They require surgical excision, with retroperitoneal lymphadenectomy if malignant.

References

Henley, J.D., Young, R.H. and Ulbright, T.M. Malignant Sertoli cell tumors of the testis: a study of 13 examples of a neoplasm frequently misinterpreted as seminoma. Am J Surg Pathol 2002;26:541-50.

This page last revised 21.3.2003.