In which type of tumor are Reinke crystals found?

Reinke crystals are specifically associated with Leydig cell tumors, which are tumors of the testes that arise from the Leydig cells responsible for testosterone production. These crystals are needle-like structures that can be observed within the cytoplasm of Leydig cells when examined under a microscope. The presence of Reinke crystals is considered a characteristic histological feature of Leydig cell tumors and serves as a diagnostic aid in pathology.

In contrast, other types of tumors listed do not harbor Reinke crystals. For instance, serous cystadenomas are primarily ovarian tumors that do not contain these structures, and seminomas, which are germ cell tumors of the testes, have a different histological profile without Reinke crystals. Follicular adenomas are benign thyroid tumors that also do not possess Reinke crystals. Therefore, the identification of Reinke crystals can effectively indicate the presence of a Leydig cell tumor among the other tumor types mentioned.