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Rare presentation of subcapsular hepatic steatosis in a woman with uncontrolled diabetes without peritoneal dialysis: a case report
© The Author(s). 2016
Received: 19 July 2016
Accepted: 21 November 2016
Published: 20 December 2016
Subcapsular hepatic steatosis is a rare atypical pattern of fatty deposition of the liver reported in patients with diabetic nephropathy receiving peritoneal dialysis with intraperitoneal insulin. To date, there has been only one pediatric and zero adult cases of subcapsular hepatic steatosis with no history of continuous ambulatory peritoneal dialysis. We report the first published case of subcapsular hepatic steatosis in an adult diabetic patient without any history of peritoneal dialysis or evidence of chronic renal disease.
A 46-year-old Caucasian woman with type 2 diabetes mellitus without renal disease presented to our emergency department with vague abdominal symptoms and vomiting. Her blood glucose levels were poorly controlled with a range of 400 to 500 mg/dL. She was diagnosed as having subcapsular hepatic steatosis based on magnetic resonance imaging. Of note, after improved glucose control her subcapsular hepatic steatosis had nearly resolved.
Subcapsular hepatic steatosis has been exclusively described in patients with continuous ambulatory peritoneal dialysis and those on intraperitoneal insulin, except for one pediatric case, which was probably due to incorrect insulin administration. Our case demonstrates that a diagnosis of subcapsular hepatic diagnosis should not be restricted to those getting continuous ambulatory peritoneal dialysis, but rather expanded to all patients with uncontrolled blood glucose levels.
Subcapsular hepatic steatosis (SHS) is an unusual and rare pattern of fatty deposition of the liver that was first described by Wanless et al. in 1989 . With the exception of one pediatric case, all previously published cases of SHS have been associated with continuous ambulatory peritoneal dialysis (CAPD) with intraperitoneal insulin. One theory for the unusual pattern of SHS is that CAPD exposes the subcapsular hepatocytes to a higher concentration of insulin than the remainder of the liver. Subsequently, the insulin blocks the oxidation of free fatty acids in the hepatocytes and leads to preferential esterification of triglycerides which then accumulate within the cell .
The most common patterns of hepatic steatosis are diffuse versus focal depositions adjacent to the falciform ligament or gallbladder fossa . However, several cases of atypical distribution have been described in the literature. In particular, patients with diabetic nephropathy on CAPD with intraperitoneal insulin have been shown to have a rare pattern of fat deposition that can be seen on computed tomography (CT) and magnetic resonance imaging (MRI). The pattern is often described as discrete and nodular subcapsular hypoattenuating lesions . Although there has been no clinical adverse effect reported from this unusual fatty infiltration, it is important to understand this entity in order to differentiate it from other similarly low attenuation lesions such as metastatic cancer, primary infiltrative neoplasms, hamartomatous lesions, hematomas, or abscesses [3, 4].
Hepatic steatosis is characterized histologically by triglyceride accumulation within the cytoplasm of hepatocytes. The two most common causes are associated with alcohol-related liver disease and insulin resistance/metabolic syndrome. It is very common to diagnose hepatic steatosis on cross-sectional imaging of the abdomen, as the prevalence is approximately 15% in the general population . It is important for the radiologist to understand both the typical and atypical pattern of fat accumulation as some may mimic neoplastic disease, inflammatory changes, or vascular infarcts. Patients are generally asymptomatic.
Although the gold standard of diagnosing hepatic steatosis is liver biopsy, the diagnosis of fatty liver can confidently be made with imaging. Diffuse fat deposition in the liver is the most frequently encountered pattern; however, there are four other main types: focal deposition and focal sparing, multifocal deposition, perivascular deposition, and subcapsular deposition . Focal deposition and focal sparing characteristically occur adjacent to the falciform ligament, in the porta hepatis, and adjacent to the gallbladder fossa. Multifocal deposition is an uncommon pattern where multiple round or oval fat foci are scattered throughout the liver and may mimic true nodules. Perivascular deposition is characterized by halos of fat that surround the hepatic vasculature and create a tram-like or tubular pattern. The last type is a subcapsular deposition pattern, which has been described in the literature with patient on CAPD with insulin added to the dialysate.
Other than one pediatric case in 2012, SHS has been exclusively described in patients with CAPD . Ours is the first adult case of SHS without any history of CAPD or other forms of intraperitoneal insulin therapy. As described by Choh , one rationale for the pathogenesis of this pattern of fatty liver without CAPD is that it could be secondary to an incorrect technique of insulin delivery to the anterior abdominal wall, thereby inadvertently creating intraperitoneal spillage. Although possible, this is unlikely in our patient given her body habitus and noncompliance with medications.
One significant differential of SHS is hepatic infarctions. An important factor that would differentiate this entity from SHS is vessels coursing through the hypoattenuated areas, making an infarct less likely. Although this finding was present in our case, our patient underwent an abdominal MRI scan (Fig. 2) which confirmed that the hypoattenuated regions were composed of fat.
Hepatic steatosis is a common entity in the general population. The incidence increases in patients with hyperlipidemia, hypercholesterolemia, obesity, and diabetes. It is important to understand the various patterns of hepatic steatosis, as well as their respective clinical correlates. Furthermore, it is important to appreciate that the different patterns of hypoattenuation may mimic other conditions. Although SHS predominantly occurs in patients undergoing CAPD with intraperitoneal insulin, our case demonstrates that the pattern of SHS should be considered in the differential even in patients who have not received CAPD.
The authors would like to thank our patient for sharing her presentation for this manuscript.
There was no source of funding for this research.
Availability of data and materials
The data and materials in this manuscript are not made available to any readers since they contain the patient’s personal particulars.
VC gathered all laboratory and imaging data and drafted the manuscript. JG participated in the case design and image evaluations. RS conceived the case report, performed image evaluations, and helped draft the manuscript. All authors read and approved the final manuscript.
The authors declare that they have no competing interests.
Consent for publication
Written informed consent was obtained from the patient for publication of this case report and any accompanying images. A copy of the written consent is available for review by the Editor-in-Chief of this journal.
Ethics approval and consent to participate
This article meets the publication standards of our hospital’s Institutional Review Board (IRB) and Ethics committee.
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