Abstract: Objective Adrenal teratoma is a rare germline tumor with a malignant potential. We present a case of left adrenal
teratoma complicated by diabetes. The 64-year-old female patient showed multiple cystic space-occupying masses in the left
kidney in B-mode ultrasound examination, and plain and enhanced CT reported a 9.0 cm heterogeneous mass in the left
adrenal gland. After effective control of blood glucose, the mass was surgically removed and sent for pathological
examination. The mass consisted of multiple cysts containing lipid-like substance with a cyst wall thickness of 0.2-0.4 cm; bony
structures were found on the sections of the mass with fat tissues on the mass surface. A final diagnosis of left cystic mature
adrenal tetrama was made based on the clinical and pathological findings and literature review. The patient was followed up
for 6 months and no local recurrence or metastasis was found. Mature adrenal teratoma can be easily diagnosed by ultrasound
and CT examinations and should be distinguished from other tumors of an adrenal source. Early diagnosis and early surgical
resection is key to the treatment, and a definite diagnosis can be made pathologically. Chemotherapy is necessary in inoperable
cases or for such tumors with a malignant potential. The patients should be followed up for life time after the treatment.