Presentations

Abstract

Introduction: "Starry Sky" appearance of the liver is a sonographic sign characterized by diffuse hypoechogenicity of the liver parenchyma with relative hyperechogenicity of the portal venule walls. Edematous changes of parenchymal hepatocytes creates a background of hypoechoic "night sky", while relative hyperechogenicity of the portal venules create diffuse "stars". This finding, classically described in the setting of acute hepatitis, has relatively low sensitivity and specificity and may appear in a variety of settings including toxic shock syndrome, lymphoma, pre-eclampsia, or diabetic ketoacidosis. This finding has also been described in the setting of a fasting liver, when glycogen store depletion causes decreased echogenicity of the liver parenchyma. In this case report, we describe an 18 year old female with starry sky liver appearance in the setting of starvation ketosis secondary to poor PO intake and severely low BMI.

Case Information: The patient is an 18 year old female with unremarkable medical history presenting to the emergency department with complaints of abdominal pain, nausea, and vomiting of 2 days' duration. Symptoms began after eating, with pain described as crampy, dull, and localized to the mid-abdomen without radiation. The patient reported that these symptoms had been recurrent for the past two years and previously resolved without treatment. On exam, vitals were unremarkable and physical exam was notable only for mild dehydration. BMI was noted to be 15.3, considered severely underweight. Laboratory studies showed leukocytosis, elevated anion gap with normal bicarbonate, and mild elevation of liver enzymes. Urinalysis showed moderate ketonuria. Noncontrast CT of the abdomen and pelvis demonstrated mild nonspecific ground-glass opacities at the bilateral lungs bases but otherwise was unremarkable. Liver, gallbladder, and bile ducts appeared normal with no acute process identified. Due to concerns for cholecystitis, ultrasound of the right upper quadrant was obtained. Gallbladder and bile duct evaluation was unremarkable, but diffuse "starry sky" appearance of the liver was noted. The patient reported improvement in her symptoms following a dose of ondansetron and declined further workup. She was discharged with recommendations for follow-up.

Discussion/Clinical Findings: Historically, the starry sky liver sign has been associated most strongly with acute hepatitis. While hepatitis workup was not obtained on our patient, a greater elevation of the liver enzymes would be expected. In the setting of postprandial abdominal pain, severely low BMI, elevated anion gap, ketonuria, and a mild elevation in liver enzymes, a feeding or eating disorder such as anorexia nervosa should be considered. While we cannot definitively exclude acute hepatitis, the patient's history and mild elevation in liver enzymes suggest another underlying process. We suggest that the starry sky liver appearance may be the result of increased hepatic metabolic demand in the setting of severely low BMI complicated by poor PO intake in the setting of acute gastrointestinal illness. The starry sky sign, while nonspecific, may still offer clinical relevance as an indicator for acute liver injury. Such acute injury may occur in the setting of increased demand of hepatic metabolism, as occurs in the setting of early starvation. As glycogen stores are depleted and ketogenesis begins, hepatocytes may swell and show decreased sonographic echogenicity. As a result, the starry sky sign may be an indicator of early starvation ketosis and insufficient glycogen storage. Patients with severely low BMI may demonstrate decreased glycogen stores at baseline. These patients may be at greater risk of developing acute liver injury and resulting starry sky sign in the setting of decreased PO intake leading to early ketosis.

Conclusion: Traditionally, the starry sky sign has been associated with acute hepatitis. However, the sign is largely nonspecific and may be present in other pathologies associated with increased hepatic demand, such as the early stages of starvation ketosis. Clinicians and radiologists must be aware of the pathophysiology underlying the starry sky appearance and tailor workup and management appropriately.