IPLab:Lab 1:Fat Necrosis

Clinical Summary

This was a 37-year-old female with chronic renal failure that necessitated a renal transplant. Following transplantation, the patient developed a herpes simplex virus (HSV) infection 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

	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).
	This gross photograph of the pancreas from this case shows white nodules (arrows) in the pancreas and the adjacent mesenteric fat tissue.
	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 in the fat adjacent to the pancreas (2).
	This high-power photomicrograph shows areas of inflammation (1) and fat necrosis (arrows) in the peripancreatic fat tissue (2) of the pancreas from this case.
	Another high-power photomicrograph shows blue discoloration in the fat tissue in the interlobular spaces (1) of the pancreas.
	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 is a higher-power photomicrograph of the fat necrosis involving the fat cells in the interlobular spaces (arrow) of the pancreas. Note the blue to purple staining of the calcium deposits within the fat cells.
	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.
	This is another high-power photomicrograph demonstrating the calcification (arrows) seen in fat necrosis involving the interlobular spaces of the pancreas.

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: Empyema and Abscess Pneumonia
• Merck Manual: Lung Abscess

Journal Articles

• Brandenburg JA et al. Clinical presentation, processes and outcomes of care for patients with Pneumococcal pneumonia. J Gen Intern Med 2000 September; 15(9): 638–646.

Images

• PEIR Digital Library: Lung Abscess Images
• WebPath: Pulmonary Pathology Images

Related IPLab Cases

• Lab 3: Lung: Lobar Pneumonia
• Lab 3: Lung: Bronchopneumonia