Allen, Philip W. MBBS, FRCPA
CASE ID AND SOURCE
AMR #59, case 1: GVH H-04021, (FMC10/S06813). Case referred by Dr Terry Schultz, Department of Anatomical Pathology, Goulburn Valley Health, Shepparton, Victoria 3630, Australia.
A 75-year-old male presented with a lesion that was thought to be a giant cell tumor located on the dorsum of the right hand. The specimen consisted of a smooth surfaced, roughly egg-shaped piece of tissue 35×30×24 mm with a delicate external capsule. The cut surface had a whorled appearance.
Sclerotic (fibroma-like) lipoma, dorsum of right hand.
The histology of this tumor (Figs. 1–5) closely matches the description in the 2006 paper by Laskin et al.1
Sclerotic lipoma was first described by Zelger et al2 in a series of 5 cases which included 3 on the scalp and 2 on the fingers. However, Laskin and colleague’s group only retrieved tumors from the hands, feet, wrist, or ankle so it is possible the tumor also has a predilection for the scalp.
Mast cells are a feature that sclerotic lipoma shares with spindle cell lipoma, and the current tumor was CD34 positive. Some of Laskin and colleague’s tumors were also weakly CD34 positive, which raised the possibility of a relationship to spindle cell lipoma.
Do any of the panel members, particularly the 2 club members who were coauthors of Laskin and colleague’s paper, have any new information about monosomy or partial loss of chromosomes 13 or 16 in sclerotic lipomas?
CLUB MEMBERS’ ANONYMOUS OPINIONS
* I thought this could correspond to a spindle cell lipoma. Thanks for bringing me up the awareness of this entity (sclerotic fibroma-like lipoma).
* For a change, something whose name seems to correspond to the histology in a straightforward fashion. This had a vague “neural” appearance to me when I first looked at it. In looking through PubMed I came across a reference to superficial acral fibromyxoma whose abstract states that these lesions had conspicuous mast cells. Is there any relation?
* I would defer to Michal and Markku but the lesion seems to fit the description of sclerotic (fibroma-like) lipoma. There certainly is a resemblance to spindle cell lipoma.
* Certainly benign spindle cell lesion. I leave the fancy nomenclature to the soft tissue mavens (Maven=a trusted expert in a particular field who seeks to pass knowledge on to others) (Wikipedia).
* Sclerotic (fibroma-like) lipoma, dorsum of right hand. I did not know this precise entity.
* Agree with diagnosis.
* Thank you, Phil. I don’t recall making the diagnosis of sclerotic lipoma before. Thank you for “reviving” this tumor.
* Right on. I would have never made that diagnosis simply because I did not know about that entity.
* I do not know about loss of chromosomes in sclerotic lipoma. I believe that I have missed this diagnosis previously and signed out one or the other case due to CD34 positivity as spindle cell lipoma.
* Sclerotic (fibroma-like) lipoma. My impression is that this lesion belongs to a group of tumors composed of dendritic (as seen by me) CD34+ cells that includes: giant cell angiofibroma, solitary fibrous tumor, lipomatous hemangiopericytoma, and dendritic cell lipoma. Or better, it can be a spectrum of lesions with cellular, myxoid, lipomatous, and sclerotic phenotypes.
* Indeed a very good fit.
* I agree with the diagnosis of spindle cell lipoma with sclerosis.
* Nice case, Phil. Thank you. I do not know the entity; spindle cell lipoma with plexiform changes would be my non-educated guess.
* Sclerotic (fibroma-like) lipoma, dorsum of right hand. I agree. Morphology and CD34 positivity do suggest some link with spindle cell lipoma. Parenthetically another fibromatous tumor which is also CD34 positive is nuchal-type fibroma, which can occur also in extranuchal sites.
* Sclerotic lipoma, seems to fit the description although the features overlap with other entities. Genetic analysis would be of interest.
* I think that some of these lesions (perhaps this one too) fit within the spectrum of low-grade spindle cell liposarcoma, which shows a predilection for subcutaneous somatic soft tissue and exhibits more frequent recurrence than spindle cell lipoma. There seems to be mild nuclear atypia and there are small numbers of convincing signet ring as well as bivacuolated lipoblasts with mildly hyperchromatic nuclei.
* Lipoma variant sounds ok.
* Perhaps the tumour might have a common histogenesis with solitary fibrous tumour. The accentuated sclerosis results in a clear differential diagnosis together with the atypical lipoma. Certainly, the diagnostic key is to identify the entity. I had not seen a similar case before.
* It looks like spindle cell lipoma. Sclerotic fibroma is very new to me. Thank you very much for the case, Philip.
* Lovely case, Phil. Curious to know if there is anything known about the molecular pathology in this case, particularly if it sheds any light on its possible relationship to spindle cell lipoma.
* Agree with diagnosis. I also would like to know the genetic profile.
* I thought this was a variant of spindle cell lipoma.
* A nice example of so-called sclerotic lipoma. Although the stroma looks different, there are indeed similarities to spindle cell lipoma and it would be very interesting to look for chromosomal changes in these lesions.
* (One of the coauthors of Laskin and colleague’s paper). Sclerotic (fibroma-like) lipoma. To answer Phil’s question, I am not of aware of any information of genetics concerning this tumor.
* (Another of the coauthors of Laskin and colleague’s paper). Agree on sclerotic lipoma. Atypical lipoma is a consideration, but atypia falls short.
* Interesting case. The myxoid parts of my slide remind me of superficial acral fibromyxoma but I do not have a better unifying diagnosis than sclerotic lipoma. The collagen is not like the ropy/wiry collagen in spindle cell lipoma. I guess we’ll see what Markku thinks.
* Thanks Philip for the case. It would make sense to associate this tumor with spindle cell lipoma. I understand that EMA was negative.
* Nice example of the entity described by Laskin et al. I suppose this tumor could also have been called a fibrolipoma, but fibrous tissue gets no respect in the soft tissues (it is the Rodney Dangerfield of this area), in contrast to bone, skin, and many other sites.
* Agree sclerotic lipoma. Perineurial markers negative?
* Thank you! I was not aware of this entity.
* I think this is a very apt descriptive term and interpretation for this process. It does indeed look like a lipoma that is undergoing secondary fibrotic changes. We reported a series of unusual lipomatous tumors under the term of “dendritic fibromyxolipoma” several years ago (Ann Diagn Pathol. 2:111-120, 1998), which we interpreted to be part of the spectrum of spindle cell lipoma/solitary fibrous tumors. I believe all of these lesions are closely related, albeit sufficiently distinct that they merit their own “names.” The important thing is to recognize their benign nature and not mistake them for more ominous processes.
* Nice case.
* My interpretation was that of a fibrolipoma or a spindle cell lipoma. It would be interesting to find out any more recent insights regarding potential nosologic relationships between spindle cell lipomas and sclerotic lipomas.
AUTHOR’S ADDITIONAL COMMENTS
The following immunohistochemical stains were performed after the slides had been distributed. The CD99 was positive and the S100, EMA, CD10, smooth muscle actin, and muscle specific actin were all negative. The MIB1 stained <1% of the tumor cells. A CD34 had previously been performed and was positive in the spindle cells. These immunohistochemistry results are similar to Laskin et al’s1 findings. The negative EMA rules out a sclerosing digital perineurioma.
It is 15 years since Zelger et al2 first described sclerotic lipoma affecting the scalp, hands, and feet and 6 years since Laskin et al1 reported 21 sclerotic lipomas involving either the hand or a finger. Patients’ ages ranged from 7 to 72 years (mean and median 39), there were 12 males and 9 females, the masses, which were mostly asymptomatic and solitary, ranged from 0.6 to 2.2 cm (median 1.2 cm, mean 1.3 cm) and involved fingers (N=17), hands or wrists (N=3), and toes (N=1). Microscopically, lesions were well circumscribed, of low cellularity, and consisted of cytologically bland spindle and stellate-shaped cells with a minor component of randomly dispersed adipocytes embedded in a collagenous to myxocollagenous stroma. Eight tumors were fibroma-like with dense fibrosclerotic stroma and inconspicuous blood vessels. One tumor exhibited features of spindle cell/pleomorphic lipoma, whereas another displayed a vague onion skin–like arrangement of collagen reminiscent of a sclerotic (storiform) fibroma. The mitotic activity was negligible. Nonlipogenic cells were immunoreactive for CD99 (6/6), CD34 (6/8), S100 (4/7), and smooth muscle actin (2/6). Follow-up on 8 patients (range, 1 to 20 y; median, 9.5 y) revealed no recurrence in 6 and possible persistent tumor in 2 after simple excision.1
I have been unable to find any more publications on this entity in the intervening years. Since I started to recognize the lesion about 4 years ago, I have diagnosed 2 other cases apart from AMR #59 case 1, one of which was referred in consultation (Figs. 6, 7), whereas the third came from the routine surgical pathology of my hospital, suggesting that the tumor is more common than the small numbers so far published1–3 might suggest. This is possibly because sclerotic lipoma has previously been called spindle cell lipoma, fibrolipoma, or a lipoma variant, as the club’s responses suggest.
The evidence for sclerotic lipoma as an entity separate from spindle cell lipoma is persuasive. Spindle cell lipoma hardly ever involves the hand or fingers and affects mainly the middle-aged males, whereas sclerotic lipoma occurs in a younger age group, probably does not exhibit such a male preponderance and histologically, is more sclerotic and storiform than spindle cell lipoma. In contrast, sclerotic lipoma shares a superficial location, good circumscription, myxoid change, mast cells, and CD 34 positivity with spindle cell lipoma; and one of Laskin and colleague’s tumors exhibited the histologic features of a spindle cell/pleomorphic lipoma. So far, there is no published information on the cytogenetics to tell if sclerotic lipoma has the same monosomy or partial loss of chromosomes 13 and 16 as seen in spindle cell lipomas.
It is still not clear if dendritic fibromyxolipoma4 is a variant of spindle cell lipoma or a separate entity with dendritic tumor cells but as with sclerotic lipoma, this question might be investigated by cytogenetic studies.
The CD34 stain is positive in many tumors, including spindle cell lipoma, dendritic fibromyxolipoma, giant cell angiofibroma, solitary fibrous tumor, lipomatous hemangiopericytoma, dermatofibrosarcoma protuberans, some benign cutaneous histiocytomas, gastrointestinal stromal tumors, normal and neoplastic endothelial cells, and even a variety of peripheral nerve sheath tumors.5 The stain is so nonspecific that I would be reluctant to suggest a relationship between CD34-positive tumors, lest I conclude that sclerotic lipoma is actually a vascular tumour or, to draw a longer bow, that all S100-positive lesions are somehow related.
One of the club members thought that the circulated slide exhibited mild nuclear atypia, however, others disagreed. In my opinion, the atypia in this tumor fell well short of that seen in even the most bland atypical subcutaneous fatty tumors that I have seen.6 The 2 sclerotic lipomas illustrated herein do not resemble the published pictures of spindle cell liposarcoma,7 which some might prefer to regard as high-grade atypical subcutaneous fatty tumors, nor could I find any acceptable lipoblasts on reviewing the circulated slide.
Zelger and colleague’s original report of 3 tumors on the scalp suggests that sclerotic lipoma can occur outside the hands and feet and could even be more common in extra-acral sites. Laskin and colleague’s study was restricted to tumors coded as lipoma, fibrolipoma, myxolipoma, fibromyxoma lipoma, and fibroma involving fingers, toes, hand, foot, wrist, or ankle. Unusual fatty tumors of the scalp or a control group of cases coded as sclerotic spindle cell lipoma were not retrieved and included in that study.
One of the club raised the possibility of a superficial acral fibromyxoma,8,9 which like sclerotic lipoma involves the hand but does not include fat as part of the tumor. Other soft-tissue entities peculiar to, or having a predilection for, the hand include ganglion cyst and digital myxoid cyst, implantation dermoid, Dupuytren’s fibromatoses, recurring inclusion bearing digital fibrous tumour (Reye), calcifying (juvenile) aponeurotic fibroma (Keasbey), acquired digital fibrokeratoma, cellular digital fibroma, fibroma of tendon sheath, chondroma of soft parts, fibroosseous pseudotumor of the digits, sclerosing (digital) perineurioma, myxoma of nerve sheath, lipofibromatous hamartoma of nerve, lipofibromatosis, hemosiderotic fibrolipomatous tumour, cerebriform malformation of Proteus syndrome, glomus tumor, spindle cell hemangio(endothelio)ma, plexiform fibrohistiocytic tumour, acral myxoinflammatory hyaline tumour, clear cell sarcoma, epithelioid sarcoma, alveolar rhabdomyosarcoma, and low-grade fibromyxoid sarcoma.10–12
There are now a good number of described tumors of the hands and feet, some of them only recently recognized. I am continually surprised that such a small part of the human anatomy can be host to so many different tumors.
© 2013 Lippincott Williams & Wilkins, Inc.