Anatomy and pathology of testicular tumors

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Anatomy and pathology of testicular tumors
Last literature review version 16.3: October 2008
This topic last updated: April 9, 2008
Authors
Michael H Weinstein, MD, PhD
Michelle S Hirsch, MD, PhD
Section Editors
Philip W Kantoff, MD
William K Oh, MD
Deputy Editor
Michael E Ross, MD


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INTRODUCTION — Testicular neoplasms comprise the most common solid malignancy affecting males between the ages of 15 and 35, although they represent only 1 percent of all solid tumors in men [1]. The two main categories of testicular tumors are germ cell tumors (GCTs), which account for 95 percent of cases, and sex cord-stromal tumors.

Testicular pathology is a nosologically complex subject because of the spectrum of histologic subtypes and variable clinical behavior, particular among GCTs. Prediction of biologic behavior depends upon the type(s) of tumors present, as well as clinical features, including the age of the patient and primary site (ie, testicular versus retroperitoneal), since histologically identical tumors can behave differently depending upon these clinical parameters.

A second source of confusion is the nonuniform and often complex classification schemes for testicular tumors. Separation of a few of the major subtypes can be somewhat subjective (eg, there can be morphologic overlap between embryonal carcinoma and yolk sac tumor) [2,3]; however, in many cases these distinctions may not be pivotal in the choice of therapy and management. The classification scheme used herein is relatively simple, practical, widely accepted, and of proven clinical utility (show table 1).

Pathologic evaluation is generally performed on the entire testis rather than on a biopsy sample. (See "Radical inguinal orchiectomy for testicular germ cell tumors"). Examination of the entire testis allows identification of the histopathologic tumor type, as well as an assessment of the stage and extent of the disease, both of which have an important bearing on subsequent management and prognosis (show table 2). Histologic features that help to determine higher stage include vascular or lymphatic invasion and spread beyond the tunica albuginea or into the spermatic cord [4].

TESTICULAR ANATOMY — The testis is composed of lobules of seminiferous tubules, interlobular septa, the mediastinum testis, rete testis, the tunica albuginea, and tunica vaginalis. The lobules are roughly pyramid-shaped, and each contains one to four U-shaped seminiferous tubules. Both ends of the seminiferous tubules empty into the rete testis, which is located posteriorly in the hilum of the testis, and drains into the epididymis. Normal seminiferous tubules have a basement membrane and a thin fibrous wall, and contain germ cells in various stages of maturation plus Sertoli cells. Blood vessels and lymphatics, mesenchymal supporting tissue, macrophages, and Leydig cells are contained within the intertubular interstitium.

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