0
Special Feature |

Image of the Month—Diagnosis FREE

Arch Surg. 2011;146(12):1448. doi:10.1001/archsurg.146.12.1448.
Text Size: A A A
Published online

Encapsulated fat necrosis is a benign condition that was first described in 1975 by Schmidt-Hermes and Loskant,1 with further characterization by Przyjemski and Schuster in 1977.2 Since these initial reports, a variety of different names have been alternatively used in the literature to describe these lesions. These terms include nodular-cystic fat necrosis, mobile encapsulated lipoma, encapsulated necrosis, or posttraumatic fat necrosis.3,4 The common pathogenesis is hypothesized to result from rapid infarction of adipose tissue lobules secondary to trauma and interruption of blood supply.3 This process causes the separation of necrotic adipose from the surrounding tissue and elicits an inflammatory cellular response to tissue injury coordinated by macrophage infiltration.5 This initial injury phase is followed by a fibrocellular response and the ultimate formation of a fibrous pseudomembrane or capsule that forms around the coalesced necrotic fat. This fibrous capsule creates a cleavage plane between the surrounding tissues and renders these lesions mobile. Given that these encapsulated nodules are sequestered from the blood supply, they cannot be reabsorbed and may accumulate lamellar units of fibrosis over time. The interior contents of the fibrous capsule contain necrotic fatty tissue with occasional degrees of degenerative changes, including dystrophic calcifications.

The characterization of encapsulated fat necrosis has been limited by the scarcity of cases reported in the literature. Almost all reported cases have occurred in the extremities within exposed areas that are prone to frequent or repeated blunt trauma, such as the subcutaneous tissues of the legs, arms, elbows, thighs, and back.6 These lesions have a variable appearance on radiographic imaging and may appear either solid or cystic. Histologically, fibrous septa are found to encapsulate internal contents that may include necrotic adipose tissue, inflammatory cell infiltrates, or calcification, which is thought to represent the end stage of formation.6 When these lesions are surgically removed, no recurrences within the surgical bed have been reported.4

To our knowledge, our finding is one of the first reported cases of encapsulated fat necrosis that presented as a free-floating mass within the intra-abdominal cavity of a human. Interestingly, however, this condition is found to be an occasional incidental finding in cattle when they are taken for slaughter and the abdominal contents are examined.7 In 1956, Dockerty et al8 described the pathologic characteristics of detached epiploic appendages in the abdominal cavity that developed into free-floating nodules, designated as “loose bodies” by the authors. The encapsulation of infarcted epiploic fat may in fact be more prevalent than has been reported but nevertheless remains asymptomatic and undetected. Judging from the extent of lamellar septa of fibrosis that encapsulated the necrotic fat within our specimen, it likely had been in the process of formation for many years without causing any symptoms.

Return to Quiz Case.

Submissions

The Editor welcomes contributions to the Image of the Month. Manuscripts should be submitted via our online manuscript submission and review system (http://manuscripts.archsurg.com). Articles and photographs accepted will bear the contributor's name. Manuscript criteria and information are per the Instructions for Authors for Archives of Surgery (http://archsurg.ama-assn.org/misc/ifora.dtl). No abstract is needed, and the manuscript should be no more than 3 typewritten pages. There should be a brief introduction, 1 multiple-choice question with 4 possible answers, and the main text. No more than 2 photographs should be submitted. There is no charge for reproduction and printing of color illustrations.

Correspondence: Dr Choti, Department of Surgery, Johns Hopkins University School of Medicine, 600 N Wolfe St, Blalock 665, Baltimore, MD 21287 (mchoti@jhmi.edu).

Accepted for Publication: April 6, 2011.

Author Contributions:Study concept and design: Brooke and Choti. Acquisition of data: Brooke and Choti. Analysis and interpretation of data: Brooke and Choti. Drafting of the manuscript: Brooke. Critical revision of the manuscript for important intellectual content: Brooke and Choti. Administrative, technical, and material support: Choti. Study supervision: Choti.

Financial Disclosure: None reported.

Schmidt-Hermes HJ, Loskant G. Verkalkte fettgewebsnekrose der weiblichen brust.  Med Welt. 1975;26:1179-1180
PubMed
Przyjemski CJ, Schuster SR. Nodular-cystic fat necrosis.  J Pediatr. 1977;91(4):605-607
PubMed   |  Link to Article
Hurt MA, Santa Cruz DJ. Nodular-cystic fat necrosis: a reevaluation of the so-called mobile encapsulated lipoma.  J Am Acad Dermatol. 1989;21(3, pt 1):493-498
PubMed   |  Link to Article
Gocmen R, Kerimoglu U. An unusual appearance of traumatic fat necrosis: floating fat balls.  Eur J Radiol Extra. 2008;66:e43-e45Link to Article
Link to Article
Diaz-Cascajo C, Borghi S. Subcutaneous pseudomembranous fat necrosis: new observations.  J Cutan Pathol. 2002;29(1):5-10
PubMed   |  Link to Article
Kiryu H, Rikihisa W, Furue M. Encapsulated fat necrosis: a clinicopathological study of 8 cases and a literature review.  J Cutan Pathol. 2000;27(1):19-23
PubMed   |  Link to Article
Herzog K, Burgdorf W, Hewicker-Trautwein M. Mobile encapsulated bodies comprising fat necrosis and fibrous tissue in the abdominal cavity of cows.  J Comp Pathol. 2010;143(4):309-312
PubMed   |  Link to Article
Dockerty MB, Lynn TE, Waugh JM. A clinicopathologic study of the epiploic appendages.  Surg Gynecol Obstet. 1956;103(4):423-433
PubMed

Figures

Tables

References

Schmidt-Hermes HJ, Loskant G. Verkalkte fettgewebsnekrose der weiblichen brust.  Med Welt. 1975;26:1179-1180
PubMed
Przyjemski CJ, Schuster SR. Nodular-cystic fat necrosis.  J Pediatr. 1977;91(4):605-607
PubMed   |  Link to Article
Hurt MA, Santa Cruz DJ. Nodular-cystic fat necrosis: a reevaluation of the so-called mobile encapsulated lipoma.  J Am Acad Dermatol. 1989;21(3, pt 1):493-498
PubMed   |  Link to Article
Gocmen R, Kerimoglu U. An unusual appearance of traumatic fat necrosis: floating fat balls.  Eur J Radiol Extra. 2008;66:e43-e45Link to Article
Link to Article
Diaz-Cascajo C, Borghi S. Subcutaneous pseudomembranous fat necrosis: new observations.  J Cutan Pathol. 2002;29(1):5-10
PubMed   |  Link to Article
Kiryu H, Rikihisa W, Furue M. Encapsulated fat necrosis: a clinicopathological study of 8 cases and a literature review.  J Cutan Pathol. 2000;27(1):19-23
PubMed   |  Link to Article
Herzog K, Burgdorf W, Hewicker-Trautwein M. Mobile encapsulated bodies comprising fat necrosis and fibrous tissue in the abdominal cavity of cows.  J Comp Pathol. 2010;143(4):309-312
PubMed   |  Link to Article
Dockerty MB, Lynn TE, Waugh JM. A clinicopathologic study of the epiploic appendages.  Surg Gynecol Obstet. 1956;103(4):423-433
PubMed

Correspondence

CME
Meets CME requirements for:
Browse CME for all U.S. States
Accreditation Information
The American Medical Association is accredited by the Accreditation Council for Continuing Medical Education to provide continuing medical education for physicians. The AMA designates this journal-based CME activity for a maximum of 1 AMA PRA Category 1 CreditTM per course. Physicians should claim only the credit commensurate with the extent of their participation in the activity. Physicians who complete the CME course and score at least 80% correct on the quiz are eligible for AMA PRA Category 1 CreditTM.
Note: You must get at least of the answers correct to pass this quiz.
You have not filled in all the answers to complete this quiz
The following questions were not answered:
Sorry, you have unsuccessfully completed this CME quiz with a score of
The following questions were not answered correctly:
Commitment to Change (optional):
Indicate what change(s) you will implement in your practice, if any, based on this CME course.
Your quiz results:
The filled radio buttons indicate your responses. The preferred responses are highlighted
For CME Course: A Proposed Model for Initial Assessment and Management of Acute Heart Failure Syndromes
Indicate what changes(s) you will implement in your practice, if any, based on this CME course.
NOTE:
Citing articles are presented as examples only. In non-demo SCM6 implementation, integration with CrossRef’s "Cited By" API will populate this tab (http://www.crossref.org/citedby.html).
Submit a Comment

Multimedia

Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging & repositioning the boxes below.

See Also...
Articles Related By Topic
Related Topics
PubMed Articles