This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Single Gene Disorders, Subject name: Pathology
Reinke crystalloids can be seen in which of the following sex cord-stromal tumours? 
Select and explain. 
A. Leydig cell tumour, B. Granulosa cell tumour, C. Gonadoblastoma, D. Thecoma
A: Leydig cell tumour
Answer: A: Leydig cell tumour 
Explanation: Hilus cell tumours (pure Leydig cell tumours) are rare, unilateral tumors comprised of large lipid-laden Leydig cells with distinct borders and characteristic cytoplasmic structures called Reinke crystalloids.