CASE 15421 Published on 06.02.2018

Lipoma arborescens in an adolescent

Section

Musculoskeletal system

Case Type

Clinical Cases

Authors

Mahesh Chaudhary, Leela Chaudhary, Md. Monir Uddin, Sharzia Asma–Ul Hosna, Bishwajit Bhowmik

Bangabandhu Sheikh Mujib Medical University (BSMMU),
Department of Radiology & Imaging;
Dhaka, Bangladesh;
Email:maheshchaudhary@hotmail.com

Patient

19 years, male

Categories

Area of Interest Musculoskeletal joint ; Imaging Technique MR

Procedure Diagnostic procedure ; Special Focus Inflammation ;

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Clinical History

A 19-year-old male adolescent presented with a swelling of the left knee joint for 2 years with restricted movement for 2 months. There was no history of trauma.

Imaging Findings

Magnetic Resonance Imaging (MRI) revealed a frond-like intra-articular mixed signal intensity lesion in the anterior aspect of the left knee joint, predominantly hyperintense in T1-weighted image (T1WI), less hyperintense in T2-weighted image (T2WI) and proton density image (PDI). On short T1 inversion recovery (STIR) sequences it showed signal suppression. After intravenous contrast, no appreciable enhancement was noted. There was mild joint effusion.

Discussion

Lipoma arborescens is one of the rare intra-articular lesions which is caused by inflammation of synovial fluid with deposition of mature fatty components within them. [1, 2] This term was first coined by Hoffa and was elaborated in detail by Arzimanoglu. [3, 4] The Latin term arborescens refers to the leafy appearance of a tree similar to that of a frond. [5] The anterior and superior aspect of the knee is most commonly affected, however, involvement of other appendicular joints is also reported in the literature. [5, 6, 7, 8]

The infiltration of mononuclear cells leads to an inflammatory reaction, causing hypertrophy of the synovium and deposition of mature lipocytes, showing a frond-like appearance. [9]

Magnetic Resonance Imaging (MRI) is the modality of choice for radiological diagnosis of lipoma arborescens. [10] It shows high signal intensity in T1WI, is less hyperintense in T2WI and hypointense on fat-suppressed sequences. [9, 11]
Computed tomography (CT) reveals a non-enhancing, low density, frond-like intra-articular mass. [12]
On ultrasonography (USG) a lobulated hyperechoic mass is seen mostly associated with a variable amount of joint effusion. [13]
Plain X-ray films may demonstrate feathery fatty lucency within a joint with joint effusion and bony erosion. [11]

This condition is usually benign and asymptomatic, however, synovectomy is indicated for patients with persistent pain. [9]

Lipoma arborescens is one of the rare intra-articular benign lesion, characterised by synovial proliferation with frond-like deposition of mature fatty components. MRI is the best radiological diagnostic tool for pre-operative evaluation. Although it is very uncommon, it can be one of the causes of chronic large joint swellings, especially of the knee joint. Synovectomy is indicated for symptomatic patients.

Differential Diagnosis List

Lipoma arborescens

Pigmented villonodular synovitis (PVNS)

Synovial osteochondromatosis

Synovial haemangioma

Loose bodies

Final Diagnosis

Lipoma arborescens

References

[1] H. W. Garner and J. M. Bestic (2013) “Benign synovial tumors and proliferative processes”. Seminars in Musculoskeletal Radiology vol. 17, no. 2, pp. 177–188 (PMID: 23673549)

[2] T. Hallel, S. Lew, and M. Bansal (1988) “Villous lipomatous proliferation of the synovial membrane (lipoma arborescens)”. Te Journal of Bone & Joint Surgery—American Volume, vol. 70, no.2, pp. 264–270 (PMID: 3343272)

[3] A. Hoffa (1904) “The inﬂuence of the adipose tissue with regard to the pathology of the knee joint”. The Journal of the American Medical Association vol. 43, no. 12, pp. 795–796

[4] A. Arzimanoglu (1957) “Bilateral arborescent lipoma of the knee”. Te Journal of Bone & Joint Surgery—American Volume vol. 39, no. 4, pp. 976–979 (PMID: 13438955)

[5] I. Bejia, M. Younes, A. Moussa, M. Said, M. Touzi, and N. Bergaoui (2005) “Lipoma arborescens affecting multiple joints”. Skeletal Radiology vol. 34, no. 9, pp. 536–538 (PMID: 15782340)

[6] C. Siva, R. Brasington, W. Totty, A. Sotelo, and J. Atkinson (2002) “Synovial lipomatosis (lipoma arborescens) affecting multiple joints in a patient with congenital short bowel syndrome”. Journal of Rheumatology vol. 29, no. 5, pp. 1088–1092 (PMID: 12022328)

[7] M. Levadoux, J. Gadea, P. Flandrin, E. Carlos, R. Aswad, and M. Panuel (2000) “Lipoma arborescens of the elbow: a case report”. Journal of Hand Surgery vol. 25, no. 3, pp. 580–584 (PMID: 10811766)

[8] E. Y. Chae, H. W. Chung, M. J. Shin, and S. H. Lee (2009) “Lipoma arborescens of the glenohumeral joint causing bone erosion: MRI features with gadolinium enhancement”. Skeletal Radiology vol. 38, no. 8, pp. 815–818 (PMID: 19290523)

[9] Sheldon PJ, Forrester DM, Learch TJ "Imaging of intraarticular masses". Radiographics vol. 25, no. 1, pp. 105-119 (PMID: 15653590)

[10] J. C. Vilanova, J. Barcelo, M. Villal ´ on, J. Aldom ´ a, E. Delgado, and I. Zapater (2003) “MR imaging of lipoma arborescens and the associated lesions”. Skeletal Radiology , vol. 32, no. 9, pp. 504– 509 (PMID: 12811424)

[11] Manaster BJ, Disler DG, May DA et-al (2002) Mosby Inc

[12] Greenspan A, Jundt G, Remagen W (2006) "Differential diagnosis in orthopaedic oncology". Lippincott Williams & Wilkins

[13] T. J. Learch and M. Braaton (2000) “Lipoma arborescens: high resolution ultrasonographic findings”. Journal of Ultrasound in Medicine vol. 19, no. 6, pp. 385–389 (PMID: 10841059)

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