IPLab:Lab 1:Fat Necrosis

Clinical Summary

This was a 37-year-old female with chronic renal failure who underwent a cadaveric renal transplant. Following transplantation she developed oral candidiasis, pneumonia, pyuria, and gastrointestinal bleeding. Subsequently, the patient became septic and died.

Major findings at autopsy included extensive hemorrhagic bronchopneumonia 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

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  This gross photograph shows the intestines and omentum at autopsy. Note the small (5-15 mm in diameter) white nodules on the surface of the omental and mesenteric fat tissue (arrows).
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  This gross photograph of the pancreas from this case shows white nodules (arrows) in the pancreas and the adjacent mesenteric fat tissue.
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  This low-power photomicrograph of the pancreas from this case shows the fat tissue (1) surrounding the pancreas. Note the rim of inflammatory cells (arrows) and the blue areas that represent calcified fat adjacent to the pancreas (2).
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  This medium-power photomicrograph shows the blue discoloration of the fat tissue in the interlobular spaces (1) of the pancreas. This blue to purple staining represents calcium deposits that occur after enzymatic necrosis of the fat cells releases free fatty acids.
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  A higher-power photomicrograph of the previous slide contains a small area of fat necrosis (1) in the upper right portion of the image. The fat necrosis is within the fat tissue that is normally found adjacent to the pancreas. The appearance of the pancreatic tissue in this area is somewhat disrupted due to autolysis (the pancreas autolyzes very rapidly after death) but there is some premortem necrosis as well.
• 
  This high-power photomicrograph demonstrates fat necrosis in the interlobular spaces of the pancreas. Note the granular blue-staining calcium deposits (arrows) within the fat cells. The clear areas represent artifact caused by the "washing-out" of fat from cells during tissue processing for histology.

Virtual Microscopy

Study Questions

• What is the definition of enzymatic fat necrosis?

Focal areas of destruction of fat tissue resulting from abnormal release of activated lipases.

• Where else can enzymatic fat necrosis occur besides the pancreas?

Salivary glands.

• What causes the formation of the white, chalky, nodules that are seen in the fat tissue adjacent to the pancreatic tissue?

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.

Additional Resources

Reference

• eMedicine Medical Library: Emergent Management of Pancreatitis
• Merck Manual: Acute Pancreatitis

Journal Articles

• Forsmark CE, Vege SS, Wilcox CM. Acute Pericarditis. N Engl J Med" 2016; 375:1972-1981. November 17, 2016.
• LeWinter MM. Acute Pericarditis. NEJM 2014 Dec 18;371:2410-2416.

Images

• PEIR Digital Library: Pancreas Images
• WebPath: Cellular Injury Images

Renal failure is the severe reduction of renal function and often leads to reduced urinary output.

Candidiasis is an infection by the fungus Candida in the oral cavity.

In alcoholics, aspiration pneumonia is common--bacteria enter the lung via aspiration of gastric contents.

Pyuria is the presence of white blood cells (pus) in the urine.

Sepsis is the presence and persistence of pathogenic microorganisms and their toxins in the blood.

DIC is the development of small thrombi within the microcirculation throughout the body.