Fat necrosis is necrosis affecting fat tissue (adipose tissue).[1] The term is well-established in medical terminology despite not denoting a specific pattern of necrosis.[2] Fat necrosis may result from various injuries to adipose tissue, including: physical trauma, enzymatic digestion of adipocytes by lipases,[3] radiation therapy,[4] hypoxia, or inflammation of subcutaneous fat (panniculitis).

The gross appearance of fat necrosis is as an irregular, chalky white area within otherwise normal adipose tissue.[1] Rarely, mobile encapsulated fat necrosis may instead appear as a mobile, firm, fibrous nodule deep to the skin.[5]

Pathophysiology

Trauma

Traumatic injury of adipose tissue liberates stored fat[1][3] as well as lipases[1] from adipocytes. The extracellular fat then elicits a swift inflammatory response, attracting macrophages and polymorphonuclear leukocytes which proceed to phagocytose the freed fat. The process eventually leads to fibrosis. The necrotic tissue may eventually form a palpable mass (especially if situated at a superficial site like the breast).[3]

Traumatic fat necrosis commonly affects the breast and may resemble a tumour (especially in case of calcification of the necrotic mass).[1]

Enzymatic digestion

Pancreatic conditions like acute pancreatitis,[3] pancreatic carcinoma, and pancreatic trauma[6] result in liberation of pancreatic lipase which proceeds to digest fat to form free fatty acids which subsequently combine with calcium to form soapy precipitates.[3][2]

Although the peripancreatic region is the most commonly affected (due to direct contact with enzymes), associated fat necrosis may occur throughout the body in subcutaneous tissue, hand and foot joints, and bone marrow. These extrapancreatic complications are known as pancreatic panniculitis.[6]

Clinical significance

Breast fat necrosis

Causes

Examples of causes include but are not limited to:[citation needed]

Epidemiology

Accidental trauma is the most common cause of breast fat necrosis, accounting for between 21-70% of case (often due to seat-belt injury). Symptomatic breast fat necrosis can also occur frequently after certain reconstructive surgeries, especially in free flap approaches, where it occurs after around 25% of surgeries. This is much greater than in pedicled flap approaches, where symptomatic necrosis happens in closer to 3% of cases. Breast fat necrosis is less common after breast cancer surgery, occurring in around 7% of cases. Rates following fat graft surgery range from 2-18%. Aside from known specific causes, middle aged women around with pendulous breasts, are at higher risk idiopathic (unknown cause) breast fat necrosis.[9]

See also

References

  1. 1 2 3 4 5 Strayer DS, Rubin E, Saffitz JE, Schiller AL, eds. (2015). Rubin's Pathology: Clinicopathologic Foundations of Medicine (7th ed.). Philadelphia: Wolters Kluwer Health. pp. 34–35. ISBN 978-1-4511-8390-0.
  2. 1 2 Kumar V, Abbas AK, Aster JC, eds. (2015). Robbins and Cotran pathologic basis of disease (Ninth ed.). Philadelphia, PA: Elsevier/Saunders. pp. 43–44. ISBN 978-1-4557-2613-4.
  3. 1 2 3 4 5 Cross SS (2013). Underwood's Pathology (6th ed.). Churchill Livingstone. p. 85. ISBN 978-0-7020-4672-8.
  4. ↑ "fat necrosis". www.cancer.gov. 2011-02-02.
  5. ↑ Sheehan C, Tran T, Mollaee M, Hsu S (2025-01-27). "A Case of Three Upper Extremity Lesions of Mobile Encapsulated Fat Necrosis in One Patient". Cureus. 17 (1) e78080. doi:10.7759/cureus.78080. ISSN 2168-8184. PMC 11865868. PMID 40018461.
  6. 1 2 Lee PC, Howard JM (May 1979). "Fat necrosis". Surgery, Gynecology & Obstetrics. 148 (5): 785–789. PMID 432796.
  7. ↑ Kerridge WD, Kryvenko ON, Thompson A, Shah BA (2015-03-16). "Fat Necrosis of the Breast: A Pictorial Review of the Mammographic, Ultrasound, CT, and MRI Findings with Histopathologic Correlation". Radiology Research and Practice. 2015 613139. doi:10.1155/2015/613139. PMC 4378709. PMID 25861475.
  8. ↑ Genova R, Garza RF (2020), "Breast Fat Necrosis", StatPearls, Treasure Island (FL): StatPearls Publishing, PMID 31194348, retrieved 2020-11-12
  9. ↑ Majithia J, Haria P, Popat P, Katdare A, Chouhan S, Gala KB, et al. (2023-02-16). "Fat necrosis: A consultant's conundrum". Frontiers in Oncology. 12. doi:10.3389/fonc.2022.926396.
source: https://en.wikipedia.org/wiki/Fat_necrosis