|Year : 2015 | Volume
| Issue : 3 | Page : 646
Synchronous Lipoma arborescens of bilateral wrist: An extremely rare manifestation and a new perspective on etiopathogenesis
Bal Chander1, Bhanu Awasthi2, Kamal Preet1
1 Department of Pathology, Dr. Rajendra Prasad Government Medical College, Kangra, Tanda, Himachal Pradesh, India
2 Department of Orthopedics, Dr. Rajendra Prasad Government Medical College, Kangra, Tanda, Himachal Pradesh, India
|Date of Web Publication||9-Oct-2015|
Department of Pathology, Dr. Rajendra Prasad Government Medical College, Kangra, Tanda 176 001, Himachal Pradesh
Source of Support: None, Conflict of Interest: None
Lipoma arborescens is a rare lesion wherein abnormal proliferation of adipocytes in the subsynovial region is seen. Whether it is neoplastic or not is still not entirely clear. Usually, Lipoma arborescens is seen unilaterally around knee joint but it can also be seen around tendon sheaths or bursa in adults. Multiple lesions are also reported. Involvement of wrist is extremely rare. We are presenting a case with bilateral wrist involvement by Lipoma arborescens which to the best of our knowledge is first one in English literature. There are a host of co-morbid/associated conditions reported with Lipoma arborescens out of which chronic irritation and inflammation appears to be most significant. We are proposing a novel perspective on etiopathogenesis of Lipoma arborescens based on extant understanding of cellular differentiation and information gleaned from fetal autopsies. The new perspective also explains the predilection for knee joint.
Keywords: Bilateral wrist, etiopathogenesis, hoffa′s disease, ipoma arborescens, post traumatic lipoma
|How to cite this article:|
Chander B, Awasthi B, Preet K. Synchronous Lipoma arborescens of bilateral wrist: An extremely rare manifestation and a new perspective on etiopathogenesis. J Can Res Ther 2015;11:646
|How to cite this URL:|
Chander B, Awasthi B, Preet K. Synchronous Lipoma arborescens of bilateral wrist: An extremely rare manifestation and a new perspective on etiopathogenesis. J Can Res Ther [serial online] 2015 [cited 2019 Nov 21];11:646. Available from: http://www.cancerjournal.net/text.asp?2015/11/3/646/150402
| > Introduction|| |
Lipoma arborescens is an uncommon proliferative lesion of the synovium which is characterized by villous orpolyploidal structures lined by synovial cells and underlying mature adipose tissue.  On gross examination, the lesion due to polypoidal growth gives the appearance of numerous branches and hence the word "arborescens" which originates from latin word arbor meaning tree.
Generally, it presents as a slow-growing painless swelling, however over the time, pain and even limited range of movements owing to the pressure effects manifests. The swelling is due to effusion which invariably accompanies the lesion in the joint and also due to synovial proliferation along with lipomatous infiltration. 
Most of these lesions are intra-articular and majority of them are found around the knee joints either unilateral or bilateral and rather rarely in other the joints. It is mostly mono-articular, but there are several reports of bilateral knee involvement. Rarely extra-articular location is noted around the tendon sheaths and bursa.  The tendon sheaths of the wrist are very rare site indeed and synchronous bilateral Lipoma arborescens of the wrist appears to be unique. To the best of our knowledge, the case we are presenting is the first one in English literature. In addition, we are also proposing a novel perspective on etiopathogenesis of Lipoma arborescens based on fetal autopsy findings.
| > Case report|| |
A 42-year-old male presented with swelling both wrist for 1 year, with pain both wrist joints for last 2 weeks. The patient also had tingling sensation on both hands with right more than left for the last 2 weeks. Physical examination showed soft, non-fluctuant swelling bilateral wrist joints, right larger in size than the left with shiny overlying skin. Test for median nerve compression was positive on right side. There were no features of involvement of any other joints of the body. Small joints of hand and foot were normal and there was no significant family or past history. He was manual worker by profession which involves loading/unloading heavy weights for last 10-15 years. His hemoglobin was 11.2 gm%, blood glucose levels were normal, and Rheumatoid factor was negative. He had normal liver and kidney function tests. A clinical diagnosis of complex ganglion was made. The patient was operated and volar Henry approach was opted for. The swelling was found to be encasing superficial and deep flexor tendons. Flexor retinaculum was incised and median nerve was decompressed [Figure 1]. The tissue along with inflamed synovium was removed and sent for histopathology.
Histopathological examination of the sections taken showed multiple villi lined by synoviocytes 3-5 layers thick with underlying mature adipose tissue and foci of dense lymphoplasmacytic infiltrate [Figure 2].
|Figure 2: x4, (H and E) Showing villous fronds lined by synoviocytes and underlying mature adipose tissue along with inset focal dense lymphoplasmacytic infiltrate (inset)|
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Subsequently, after 2 months, he was operated on the other side and histomorphological features were identical to that of the previous specimen.
A diagnosis of Lipoma arborescens, bilateral wrists was made.
| > Discussion|| |
Lipoma arborescens is an unusual and uncommon lesion featuring sub synovial deposition of mature adipose tissue in villous or polypoidal structures. Clinically, there is presence of a boggy swelling. Magnetic resonance imaging (MRI) is the investigation of choice, with images best visualized on fat suppressed or short tau inversion recovery (STIR) sequences. The classical appearance is of multiple villous lipomatous proliferations of fat signal intensity.  Synovectomy is curative; however, associated pathologies may continue to progress.  Microscopy shows villous expansion of synovium lined by a few layers of synoviocytes and underlying mature adipose tissue admixed with variable amount of lymphoplasmacytic infiltrate. , About the histogenesis of this condition, Hallel et al., are of the opinion that it is a reactive process, whereas Liddle et al., have proposed it to be a neoplastic lesion. , Most certainly, it is not a malignant lesion and has not been observed to behave as such.
It is not uncommon to find the lesion arising de novo; however, there are also cases found to have association with conditions such as local trauma, meniscal injuries, psoriatic arthritis, osteoarthritis, rheumatoid arthritis, diabetes mellitus, and gout. , According to the largest study by Vilanova JC et al., all but two of the 33 cases had some other associated pathology of the knee. Furthermore, 94% of the cases were of unilateral knee.  The history of injury is almost universal but the nature of it may vary.  Chronic inflammation is invariably present. Role of lymphoplasmacytic inflammation appears to be quite important and is hard to ignore given the fact that it is present in almost all histopathologically proven cases of Lipoma arborescens.
The results therefore appear to support the prevalent hypothesis that Lipoma arborescens is a reactive proliferative condition in response to chronic irritation, injury or inflammation.
However, that does not explain the rarity of these lesions among abundant cases of reported associated conditions, particularly the ones leading to tissue damage in the joint for instance osteoarthritis and rheumatoid arthritis.
Perhaps we can find a partial explanation for rarity of Lipoma arborescens by considering the following. Only in a few individuals, this condition is seen even as co-morbid/associated conditions are very common in a given population. Therefore, these individuals must have some predisposing condition which is responsible for occurrence of Lipoma arborescens. The predisposing condition is most likely is a local one since mostly Lipoma arborescens is a local phenomenon, although a few multiple lesions are reported.
We propose that in the individuals with Lipoma arborescens, the predisposing condition is abnormal retention of preadipocytes or multi/pleuripotent stem cells in the subsynovial region.
To support our hypothesis, we took cross-sections from the wrists and synovial tissue of knee joints from five fetuses that had come for autopsy. We found that in all the fetuses, adipocytes were present in the subsynovial region from both sites. However, the adipocytes were far more numerous in the synovium from knee as compared to synovium from the tendon sheaths in the wrists [Figure 3]. It stands to reason to assume that this relative distribution in maintained as the individual matures even as the abundant subsynovial adipocytes in fetuses are reduced to occasional ones in adults. Therefore, the number of subsynovial adipocytes in the knee joint should be more than the tendon sheaths of wrist in adults. It is well-known that by adulthood only a few adipocytes are seen in subsynovial area. 
|Figure 3: x40, (H and E) Synovial tissue from knee joint of 28-week-old fetus showing abundant mature adipocyes under the synovial lining (left). Tendon sheath from wrist of 28-week fetus showing adipose tissue and loose areolar tissue (right)|
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Hence, knee is more predisposed to develop Lipoma arborescens than the wrist.
Most common location of Lipoma arborescens is around knee joint also because the microenvironment is already predisposed toward adipocytic differentiation given the presence of sub-patellar fat deposits.
In the individuals with Lipoma arborescens, there should be more subsynovial adipocytes compared to rest of the population The distribution of adipocytes may be focal or diffuse. Hence, in the face of similar nature of injury in a given population, the individuals with more preadipocyes are likely to develop lipomatous proliferations.
However, it should not be erroneously concluded that obese individuals should be more prone to develop Hoffa's disease because we are only alluding to adipocytes in subsynovial region which should be independent of obesity.
| > References|| |
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Hallel T, Lew S, Bansal M. Villous lipomatous proliferation of the synovial membrane (lipoma arborescens). J Bone Joint Surg Am 1988;70:264-70.
Liddle A, Spicer DD, Somashekar N, Thonse C. Lipoma arborescens of both knee- case report and literature review. J Orthop Case Rep 2012;2:3-7.
Smith MD. The normal synovium. Open Rheumatol J 2011;5:100-6.
[Figure 1], [Figure 2], [Figure 3]