Gonadoblastoma and selected other aspects of gonadal pathology in young patients with disorders of sex development.

Some patients with disorders of sex development (DSDs), previously known as intersex disorders, have abnormal gonadal development and an increased risk of germ cell tumors. Because of their relative rarity, however, many pathologists are unfamiliar with the morphological findings in the gonads of DSD patients and their clinical significance. This review concentrates on some of the most common DSDs where gonadal specimens may come to the attention of pathologists. It highlights the findings in gonadal dysgenesis, a DSD with a spectrum of clinical, pathologic, and molecular features but with the shared attributes of having both Y chromosomal material (even if in very limited amounts) in the gonad and also having mutations or deletions in genes necessary for normal gonadal development, mostly in those upstream of the SOX9 gene. This situation results in testicular tissue lacking normal Sertoli cells, which are now considered an essential element for the normal maturation of the primordial germ cells that migrate to the gonad from the embryonic yolk sac. Germ cells with delayed maturation mimic neoplastic germ cells, but there are both morphological and immunohistochemical differences. If the gonad having germ cells with delayed maturation also harbors the TSPY gene on the GBY locus of the Y chromosome, the cells may undergo neoplastic transformation and result in the distinctive gonadoblastoma, whose pathologic features are explored at length herein, including its potential for variant morphologies, such as a "dissecting" pattern. Another important DSD, the androgen insensitivity syndrome (AIS), is discussed at length, including the varied appearances of the testis and its distinctive lesions-hamartomas and Sertoli cell adenomas. The potential for germ cell neoplasia in the partial AIS is also discussed and contrasted with that of the complete AIS. A third major topic is ovotesticular DSD (true hermaphroditism). The clinical features and morphology of this condition are reviewed, including the arrangements of the tissue components in an ovotestis. Several other DSDs with distinctive gonadal findings are also considered, including Klinefelter syndrome, 5α-reductase deficiency, 17β-hydroxysteroid dehydrogenase deficiency, and female adrenogenital syndrome.