Gonadoblastoma, light micrograph. Gonadoblastoma is an uncommon tumour containing cellular nests of dysgerminoma-like primitive germ cells and sex cord cells resembling Sertoli and granulosa cells. It almost always occurs in children or young adults with gonadal dysgenesis. About 80% of patients are phenotypic females; the rest are phenotypic males or have ambiguous genitalia. The cell nests are separated by hyalinised stroma. Calcification of the stroma is commonly present (top and left edge of the image) and may be extensive. Some tumours are completely calcified and are often detected incidentally on pelvic or abdominal X-rays ordered for other reasons. Haematoxylin and eosin stained section. Magnification: x100 when printed at 10 centimetres wide.