These tumors are rare and are mostly hereditary. Most of them are solid masses with well-defined borders. The tumor cells are arranged in solid, nested, or tubular structures; the cytoplasm is vacuolated and eosinophilic to hyaline, with regular smooth nuclear contours, fine chromatin, and inconspicuous nucleoli (similar to neuroendocrine cells); the cytoplasm is vacuolated; and high-grade nuclei are occasionally seen. Immunohistochemistry showed a deficiency in succinate dehydrogenase expression, with succinate dehydrogenase B expression being the most common.