Dias, André FontesDvindenko, EugéniaSantos, FilipaCabrera, Rafael2023-07-312023-07-312022Int J Surg Pathol. 2023 Aug;31(5):728-7331066-8969http://hdl.handle.net/10451/58799© The Author(s) 2022. This article is distributed under the terms of the Creative Commons Attribution-NonCommercial 4.0 License (https://creativecommons.org/licenses/by-nc/4.0/) which permits non-commercial use, reproduction and distribution of the work without further permission provided the original work is attributed as specified on the SAGE and Open Access page (https://us.sagepub.com/en-us/nam/open-access-at-sage).Spermatocytic tumour (ST) accounts for 1% of testicular germ cell tumours. It is an indolent neoplasm with good prognosis. In approximately 6% of STs, sarcomatous dedifferentiation may occur, portending an aggressive behaviour and representing a significant diagnostic challenge that can lead to its misdiagnosis. Herein, we report the clinicopathological features of a patient with a sarcomatoid spermatocytic tumor, initially diagnosed as mixed germ cell tumour, who was referred to our institution with lung metastases mainly composed of rhabdomyosarcomatous elements. This case report illustrates the importance of recognizing this entity for adequate management of these patients.engMetastasisRhabdomyosarcomaSarcomatoid spermatocytic tumourSarcomatous dedifferentiationSpermatocytic tumourjournal article10.1177/106689692211229951940-2465