IGCNU and Leydig cell hyperplasia are frequently present.
Coexisting IGCNU is a key feature in distinguishing TGCT from many mimickers.
Atypical germ cells, some of which may simulate IGCNU, can be seen in the testes of patients with cryptorchidism, hypofertility or infertility, sex development disorders, and, sometimes, in the background testis of pediatric TGCTs.
(54) They may closely resemble IGCNU cells, but, in contrast to true IGCNU, they lack basilar location and segmental distribution.