Fettnekros

Fettnekros, or fat necrosis, is the death of fat tissue as a result of injury, enzymatic digestion, or reduced blood supply. It can affect any fat-containing region but is most commonly described in subcutaneous fat of the breast or abdominal wall, as well as in the peripancreatic fat during pancreatitis. The condition may be solitary or multifocal and can develop soon after trauma or surgery, or gradually in chronic inflammatory settings.

The underlying mechanism involves disruption of adipocytes and release of triglycerides, followed by inflammatory processing. In pancreatitis, pancreatic lipase leaks into surrounding fat and causes enzymatic fat necrosis or “saponification,” often with calcium deposition. In non-pancreatic sites, trauma or ischemia initiates adipocyte death and an accompanying inflammatory response that can lead to oil-filled cavities or calcifications over time.

Clinical presentation varies. Fat necrosis in the breast may present as a painless lump, a firm mass, skin changes, or calcifications on imaging, and can resemble breast cancer radiographically. In the abdomen, patients may have focal tenderness or palpable masses; in pancreatitis-associated fat necrosis, systemic signs of inflammation are common. Imaging studies (ultrasound, mammography, CT, or MRI) often reveal fat-containing lesions, oil cysts, or calcifications; biopsy may be needed when malignancy cannot be excluded.

Treatment generally focuses on the underlying cause and symptom management. Most fat necrosis is benign and self-limited; observation is common, with intervention reserved for cases that are symptomatic, progressive, or suspicious for malignancy. Prognosis is typically good, though persistent masses may require follow-up or biopsy to rule out cancer.