Evaluation of testicular biopsy samples from the clinical perspective

Abstract

Testicular biopsy is indicated therapeutically in cases of obstructive azoospermia, and also in cases of hypergonadotrophic testicular azoospermia to recover testicular spermatozoa (testicular sperm extraction = TESE) for assisted reproduction by intracytoplasmic sperm injection (ICSI). A diagnostic biopsy is indicated in cases of refertilization after vasectomy, and also to exclude a testicular tumour. According to European Association of Urology (EAU) guidelines, several testicular samples from three different locations should be taken because of regional differences in spermatogenesis. Histological evaluation is recommended instead of testicular fine needle aspiration (TEFNA). Specimens should be fixed in Bouin's solution to ensure good preservation of tissue structure and to allow the application of modern histological techniques such as in situ hybridization and immunohistochemistry for evaluating gene expression at the mRNA and protein levels. Diagnosis of pre-invasive carcinoma in situ (CIS, synonym: testicular intraepithelial neoplasia = TIN) is based on the immunohistochemical demonstration of placentalike alkaline phosphatase (PLAP), which is exclusively expressed in CIS cells. Histological evaluation should be performed using a score count system, determining at least the percentage of seminiferous tubules containing elongated spermatids, which is the most important parameter for TESE/ICSI, together with a cytological analysis, which gives further causal evidence for the observed spermatogenic impairment. Testicular biopsy is an invasive surgical operation with a high impact on patients with severe spermatogenic impairment, and should therefore be performed only by considering strict criteria of indication, surgical procedure and histological evaluation in qualified centres that are certified, i.e. recommended by the European Academy of Andrology (EAA). © 2006 Springer-Verlag Berlin Heidelberg.