Fat necrosis is

necrosis Necrosis () is a form of cell injury which results in the premature death of cells in living tissue by autolysis. The term "necrosis" came about in the mid-19th century and is commonly attributed to German pathologist Rudolf Virchow, who i ...

affecting fat tissue (adipose tissue). The term is well-established in medical terminology despite not denoting a specific pattern of necrosis. Fat necrosis may result from various injuries to adipose tissue, including: physical trauma, enzymatic digestion of

adipocytes Adipocytes, also known as lipocytes and fat cells, are the cells that primarily compose adipose tissue, specialized in storing energy as fat. Adipocytes are derived from mesenchymal stem cells which give rise to adipocytes through adipogenesis. ...

lipases In biochemistry, lipase ( ) refers to a class of enzymes that catalyzes the hydrolysis of fats. Some lipases display broad substrate scope including esters of cholesterol, phospholipids, and of lipid-soluble vitamins and sphingomyelinases; how ...

radiation therapy Radiation therapy or radiotherapy (RT, RTx, or XRT) is a therapy, treatment using ionizing radiation, generally provided as part of treatment of cancer, cancer therapy to either kill or control the growth of malignancy, malignant cell (biology), ...

, 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.

Pathophysiology

Trauma

Traumatic injury of adipose tissue liberates stored fat as well as lipases from

. The extracellular fat then elicits a swift inflammatory response, attracting

macrophages Macrophages (; abbreviated MPhi, φ, MΦ or MP) are a type of white blood cell of the innate immune system that engulf and digest pathogens, such as cancer cells, microbes, cellular debris and foreign substances, which do not have proteins that ...

and

polymorphonuclear leukocytes Granulocytes are cells in the innate immune system characterized by the presence of specific granules in their cytoplasm. Such granules distinguish them from the various agranulocytes. All myeloblastic granulocytes are polymorphonuclear, that is ...

which proceed to phagocytose the freed fat. The process eventually leads to

fibrosis Fibrosis, also known as fibrotic scarring, is the development of fibrous connective tissue in response to an injury. Fibrosis can be a normal connective tissue deposition or excessive tissue deposition caused by a disease. Repeated injuries, ch ...

. The necrotic tissue may eventually form a palpable mass (especially if situated at a superficial site like the breast). Traumatic fat necrosis commonly affects the breast and may resemble a tumour (especially in case of calcification of the necrotic mass).

Enzymatic digestion

Pancreatic conditions like acute pancreatitis, pancreatic carcinoma, and pancreatic trauma result in liberation of

pancreatic lipase Pancreatic lipases () are a protein family, family of lipolytic enzymes that hydrolyse ester linkages of triglycerides. Lipases are widely distributed in animals, plants and prokaryotes. At least three tissue-specific isozymes exist in higher ...

which proceeds to digest fat to form free fatty acids which subsequently combine with calcium to form soapy precipitates. 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 The subcutaneous tissue (), also called the hypodermis, hypoderm (), subcutis, or superficial fascia, is the lowermost layer of the integumentary system in vertebrates. The types of cells found in the layer are fibroblasts, adipose cells, and ma ...

, hand and foot joints, and bone marrow. These extrapancreatic complications are known as pancreatic panniculitis.

Clinical significance

Breast fat necrosis

Causes

Examples of causes include but are not limited to: * Breast trauma (e.g. seat belt injury from a car accident) * Breast surgery ** Fine needle aspiration biopsy and cytology (FNAB, FNAC) **

Radiotherapy Radiation therapy or radiotherapy (RT, RTx, or XRT) is a treatment using ionizing radiation, generally provided as part of cancer therapy to either kill or control the growth of malignant cells. It is normally delivered by a linear particle ...

Lumpectomy Lumpectomy (sometimes known as a tylectomy, partial mastectomy, breast segmental resection or breast wide local excision) is a surgical removal of a discrete portion or "lump" of breast tissue, usually in the treatment of a malignant tumor or bre ...

** Reduction mammoplasty **

Breast reconstruction Breast reconstruction is the surgical process of rebuilding the shape and look of a breast, most commonly in women who have had surgery to treat breast cancer. It involves using autologous tissue, prosthetic implants, or a combination of both wi ...

* Pancreatic disease **

Acute pancreatitis Acute pancreatitis (AP) is a sudden inflammation of the pancreas. Causes include a gallstone impacted in the common bile duct or the pancreatic duct, heavy alcohol use, systemic disease, trauma, elevated calcium levels, hypertriglyceridemia (w ...

Pancreatic cancer Pancreatic cancer arises when cell (biology), cells in the pancreas, a glandular organ behind the stomach, begin to multiply out of control and form a Neoplasm, mass. These cancerous cells have the malignant, ability to invade other parts of ...

** Pancreatic injury * Some forms of panniculitis ** Subcutaneous fat necrosis of the newborn **

Weber–Christian disease Weber–Christian disease is a cutaneous condition characterized by recurrent subcutaneous nodules that heal with depression of the overlying skin. It is a type of panniculitis. It is a rare disease seen in females 30–60 years of age. It is a r ...

Polyarteritis nodosa Polyarteritis nodosa (PAN) is a systemic necrotizing inflammation of blood vessels (vasculitis) affecting medium-sized muscular arteries, typically involving the arteries of the kidneys and other internal organs but generally sparing the lungs' ...

Epidemiology

Fat necrosis in the breast occurs around 0.6%, this represents 2.75% of lesions that end up being

benign Malignancy () is the tendency of a medical condition to become progressively worse; the term is most familiar as a characterization of cancer. A ''malignant'' tumor contrasts with a non-cancerous benign tumor, ''benign'' tumor in that a malig ...

. However, 0.8% of fat necrosis occurs from tumors of the breast, 1–9% occurs in

breast reduction Reduction mammoplasty (also breast reduction and reduction mammaplasty) is the plastic surgery procedure for reducing the size of large breasts. In a breast reduction surgery for re-establishing a functional bust that is proportionate to the pa ...

surgery. Individuals that are high risk include women around the age of 50yrs along with pendulous breasts.

References

External links

Fat Necrosis of the breast
{{DEFAULTSORT:Fat Necrosis Pathology Necrosis Breast diseases Pancreas disorders