LAUSR

Michalova et al. [1] address the question whether mixed germ cell sex cord-stromal tumors (MGSCT) of the testis do indeed exist. This extremely rare entity, originally described by Dr. Aleksander Talerman, consists of a sex cord-stromal component resembling the adult granulosa cell tumor and interspersed germ cells [2]. The authors have published on these lesions in the past [3, 4], and became involved in a discussion with Ulbright and Young [5, 6] on the nature of the germ cells in MGSCT of the testis. Michal et al. consider the germ cells as truly neoplastic, whereas Ulbright et al. contend that the germ cells are entrapped normal germ cells, which prompted the removal of MGSCT from the WHO classification of testicular germ cell tumors of 2016 [7]. In the present paper, Michalova et al. present new evidence for the neoplastic nature of the germ cells, which showed morphological atypia, including atypical mitotic figures, and displayed invasive growth jointly with the sex cord-stromal component. More importantly, the germ cells were characterized by chromosomal aberrations, among them recurrent gain of chromosomes 9 and 20, and loss of chromosome 7, aberrations also found in spermatocytic tumors [8, 9].