Lipoma pathophysiology
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Overview
Lipomas are circumscribed encapsulated soft masses, made nearly entirely of fat. Solid components may present in some cases.
Pathophysiology
- Lipomas are defined as soft masses of adipose (fat) cells which are often encapsulated by a thin layer of fibrous tissue.
- They are benign tumors of subcutaneous fat, not attached to the underlying fascia.
- Clinically, they often present in the cephalic part of the body, specifically in the head, neck, shoulders, and backs of patients, although they can less commonly be seen elsewhere, for example, the thighs.
- The tumors typically lie in the subcutaneous tissues of patients.
- Lipomas can also arise in visceral organs such as stomach, liver, duodenum, colon, thyroid, adrenal glands, pancreas, and parathyroid glands.
- Maxillofacial lipomas, including intralingual, parotid, orbitonasal, maxillary sinusoidal, and parapharyngeal space masses, have also been documented.
- Gynecologic lipomas may occur in the uterus, ovaries, and broad ligament.
- Involvement of the heart (causing ventricular tachycardia), superior vena cava, brain, and spinal cord may also occur.
- Bone and intrarticular involvement is also common.
- Mucosal lipoms in the gatsrointestnial tract can cause bleeding and intuscception.
- Lipomas are histologically characterized by mature fat cells with no cytologic atypia/hyperchromasia/pleomorphism.
- Lipoblasts can be seen in lipomas, but they do not exhibit cytologic atypia/hyperchromasia/pleomorphism.
Genetics
- Lipomas are mainly characterized by rearrangements of chromosome 12q13q15 with several partner chromosomes in approximately, especially chromosome 3[1].
- Lipomas without 12q13q15 rearrangements frequently show rearrangements of chromosome 6p21.
- Several lipoma fusion genes have been identified and the most common is LPP-HMGA2, product of the t(3;12)(q27-q28;q14-a15).
References
- ↑ Ida CM, Wang X, Erickson-Johnson MR, Wenger DE, Blute ML, Nascimento AG; et al. (2008). "Primary retroperitoneal lipoma: a soft tissue pathology heresy?: report of a case with classic histologic, cytogenetics, and molecular genetic features". Am J Surg Pathol. 32 (6): 951–4. PMID 18551755.