Diabetic ketoacidosis (DKA) is commonly encountered in clinical practice. However, the current case represents a rare and unusual presentation, where DKA was the initial manifestation of adrenocortical carcinoma.

A 74-year-old female with a medical history of diabetes mellitus, hypertension, and dyslipidemia presented to our emergency department with chest tightness and dyspnea. She also reported lower limb swelling and edema following a long flight. A peripheral vein Doppler revealed small thrombi at multiple sites. Blood tests indicated elevated blood glucose and ketone bodies, alongside decreased potassium, carbon dioxide, and bicarbonate levels, leading to a diagnosis of DKA. The patient was admitted for treatment of both DKA and deep vein thrombosis (DVT) and was discharged a week later after stabilization. However, two days after her discharge, the patient returned to the emergency department complaining of general weakness, mild abdominal discomfort, constipation, and poor appetite. Abdominal and pelvic contrast-enhanced computed tomography (CT), along with low-dose lung CT, revealed a large right suprarenal tumor with direct invasion into the liver parenchyma, inferior vena cava, peritoneum, and retroperitoneum. Additionally, extensive hepatic and pulmonary metastasis, along with upper retroperitoneal and mediastinal metastatic lymphadenopathy, were observed. A liver biopsy confirmed poorly differentiated malignancy, consistent with metastatic adrenocortical carcinoma (ACC). Blood tests showed elevated levels of CA125, CA19-9, and cortisol. The patient's condition rapidly deteriorated, and she passed away a few days after admission.

Looking back at the patient's presentation, there were several signs that pointed to the possibility of a functional adrenal tumor. Symptoms such as dyspnea, DVT, general weakness, uncontrolled hyperglycemia, and hypokalemia are all indicative of an advanced functional ACC. On the other hand, DKA is not typically associated with ACC, and current literature seldom mentions DKA as a presenting feature of Cushing syndrome, much less ACC.

The symptoms of advanced functional ACC can often be subtle and nonspecific. Therefore, when encountering patients with DKA and DVT, it is important to consider ACC as part of the differential diagnosis.