Fat necrosis

Associate Editor-In-Chief:

Overview
Fat necrosis is a focal area of destruction of fat tissue resulting from abnormal release of activated lipases.

Injury to the pancreas (infection, toxins, viruses, trauma, ischemia) causes release of activated pancreatic enzymes which liquefy fat cell membranes. The released lipases split the triglyceride esters contained within the fat cells and these released fatty acids combine with calcium to form the grossly visible chalky white nodules characteristic of fat necrosis.

Mammogram

 * Mammographic spectrum of appearances of fat necrosis ranges from the characteristically benign to the potentially malignant.
 * Calcifications seen at mammography may be clear-cut, benign rings, rims, or coarse macrocalcifications or may manifest as suspicious pleomorphic or even "branching type" microcalcifications.

Ultrasound

 * Masses are most commonly solid, although they may be complex or cystic.
 * Borders may be discrete or ill-defined.
 * Posterior shadowing or enhancement may be present.

MRI

 * Signal follows that of fat: Bright on T1 with loss of signal of fat saturated images.

Images courtesy of RadsWiki

Clinical Summary
A 37-year-old female with chronic renal failure that necessitated a renal transplant. Following transplantation, the patient developed a herpes simplex virus infection (HSV) in her nasal cavity, oral candidiasis, pneumonia, hematuria, pyuria, and gastrointestinal bleeding. Subsequently, the patient became septic and died.

Autopsy Findings
Major findings at autopsy included extensive hemorrhagic bronchopneumonia (Pseudomonas aeruginosa) and multiple ulcers affecting the stomach and esophagus. There was also evidence of disseminated intravascular coagulation (DIC) with multiple hemorrhages present. Firm, whitish foci of necrotic tissue were found in the fat around the pancreas.

Images courtesy of Professor Peter Anderson DVM PhD and published with permission © PEIR, University of Alabama at Birmingham, Department of Pathology