Fibromaof tendon sheath - BMJ

J Clin Pathol 1982;35:842-848

Fibroma of tendon sheathPS SMITH, AS PIETERSE, J McCLURE

From the Adelaide Bone and Joint Research Unit, Division of Tissue Pathology, Institute of Medical andVeterinary Science, Frome Road, Adelaide, South Australia 5000

SUMMARY A series of nine cases of fibroma of tendon sheath is described including details of theultrastructural features of two cases. The series was composed of lesions from six males and threefemales with a mean age of 38 yr. The most common site of involvement was the hand (includingfingers) and the mean greatest diameter was 19 mm. Typically the tumours were lobulated andmicroscopically there was a collagenous stroma with spindle and stellate cells in a moderatedegree of cellularity. One recurrence was noted in the series. The lesion was distinguished fromcircumscribed fibromatosis, nodular fasciitis, neurofibroma, leiomyoma, scar tissue, giant celltumour of tendon sheath (localised nodular tenosynovitis) and fibrous histiocytoma. Ultrastruc-tural studies revealed that the large majority of cells present in the two cases studied were

myofibroblasts and fibroma of tendon sheath is therefore the third instance of a benign tumourcontaining these cells (the other two being dermatofibroma and giant cell fibroma of the oralmucosa).

In his classification of tumours of tendon sheathBuxton' considered that benign tumours included(i) lipoma, (ii) fibroma, (iii) chondroma and(iv) ganglion. Obviously the latter would not be con-sidered a true neoplasm and the other three at firstsight would be considered rare. Buxton also referredto a "giant celled myeloma" which was benign butliable to recur locally. It is obvious that this entityequates to the so-called giant cell tumour of tendonsheath a lesion which is probably not a true neo-plasm and which is best regarded as a nodulartenosynovitis being a reactive proliferation of bothA and B tenosynoviocytes.2 Buxton regarded ten-don sheath fibroma as uncommon and described aspecimen from near the ankle and which was in theMuseum of the Royal College of Surgeons ofEngland. Geschickter and Copeland3 described afibroma of tendon sheath as an encapsulated tumourcomposed of tightly packed spindle cells surroundedby collagen fibres.From 1936 to 1979 no additional cases of fibroma

of tendon sheath were reported in the literatureuntil Chung and Enzinger4 described the clinical,macroscopic and light microscopical characteristicsof this tumour. They described a well circumscribedoften lobulated tumour which was usually attachedto tendon or tendon sheath. Microscopically therewas dense fibrocollagenous tissue containing usually

Accepted for publication 9 December 1981

spindle but sometimes stellate cells and frequentlybearing dilated or slit-like vascular channels some ofwhich resembled tenosynovial spaces. In the last fewyears we have had experience of nine cases of ten-don sheath lesions which fulfil the diagnostic criteriaof fibroma as laid down by Chung and Enzinger.Our experience with these lesions is reported here inview of the fact that the majority were not initiallyrecognised as fibromas and that electron microscop-ical studies were performed in two cases.

Material and methods

All tendon sheath lesions accessioned to the Divi-sion of Tissue Pathology of the IMVS over the 10-year-period 1971-80 were reviewed and nine caseswere identified which exhibited features consistentwith a diagnosis of fibroma. Haematoxylin and eosin(HE) stained sections were available in each case. Inaddition the following special stains were applied(i) Perl's Prussian blue, (ii) Masson's trichrome,(iii) Gordon and Sweet's reticulin, (iv) PAS,(v) PAS after diastase digestion, (vi) MSB,(vii) alcian blue (pH 2.5), (viii) Miller's elastin stainand (ix) von Kossa. In two cases portions offormalin-fixed tissue were post-fixed in osmium tet-roxide and processed into Spurr's resin. Survey sec-tions were cut and representative blocks were thin-sectioned for electron microscopy.A limited amount of clinical data was abstracted

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Fibroma of tendon sheath

Clinical and macroscopic data ofnine cases offibroma oftendon sheath

Case Sex Age Site Clinical history Macroscopic appearance

1 M 41 Not known Not known An encapsulated white nodule20 x 10 x 10 mm

2 M 48 Palm of left palm Swelling after injury Irregular, firm grey nodule 26 mm inmaximum diameter

3 F 26 Palmar aspect of left Not known Fibrous nodule size unknownmiddle finger

4 F 68 Back of the left hand Cystic swelling Firm, white nodule 25 x 25 x 20 mm5 M 23 Not known Not known Not known6 M 18 Right middle finger Not known Ovoid white nodule 20 x 15 x 15 mm7 F 29 Extensor tendon Described as a ganglion White nodule 7 x 5 x 2 mm

apparatus of left handRecurrence of above ,, ,, Irregular greyish tissue 12 x 8 x 5 mm

8 M 58 Ulnar aspect of distal Swelling present for a few Firm, white nodule 12 x 18 x 10 mmphalanx of left index months. Not painful Weight = 1-6 gfinger

9 M 33 Left knee Smooth rounded tumour Firm, white nodule 30 x 20 x 10 mmattached to quadricepsmechanism

from the information submitted with each biopsyand this is shown in the Table.

Results

An examination of the clinical data shows that in thenine cases there was one recurrence making 10specimens available for examination. There were sixmales and three females in the series. The mean age

was 38 yr (range 18-68 yr). The lesion was relatedto the knee in one case and to the hand in sixinstances. Three of these were related to fingers andthree to either the palmar or dorsal aspects of thehand.The mean greatest diameter was 19 mm (range

7-30 mm) and in seven specimens there was a dis-tinct lobulation. In one case mucoid areas were seen

macroscopically and in one other microscopically.Microfoci of cystic change were noted in two speci-mens. Generally the stroma was markedly collagen-ous (confirmed by the trichrome strain) and themajority of constituent cells were spindle-shaped(Figs 1, 2). Blood vessels were evenly dispersedthroughout in nine instances and only in one were

slit-like spaces prominent. Limited areas of looser,less fibrous stroma were seen in six samples and theconstituent cells were here stellate in shape (Fig. 3).Assessment of the overall degree of cellularityrevealed it to be mild in three, moderate in five andmarked in two specimens. Extravasation of erythro-cytes (in snall numbers) was seen in three cases.

Occasional multinucleated giant cells (macrophagepolykaryons) were seen in one case. Foam cells were

not seen in any of the cases studied. There was no

significant mitotic activity.Small foci of mucoid change were seen in two

cases and these areas were shown to contain an acidmucin. In two other cases there were small areas

exhibiting a storiform pattern. There was a finereticulin pattern with fibres apparent around indi-vidual cells in all cases. A small amount ofhaemosiderin was present in three specimens butthere was never any detectable fibrin. No elastin wasseen in the lesions and the von Kossa stain wasuniformly negative. True encapsulation was notseen. In several cases there was condensation ofmarginal connective tissue giving the appearance ofa pseudocapsule.

Ultrastructural studies were performed on two ofthe cases and identical features were seen in both.Sections revealed spindle and stellate cells set in acollagen matrix. The nuclei varied from regular andelongated to highly convoluted the latter beingmuch frequent (Fig. 4). Chromatin was marginatedand a prominent nucleolus was only occasionallyseen. The cytoplasm contained large amounts ofrough endoplasmic reticulum which was oftendilated by an amorphous substance. Free ribosomesoccurred in large numbers but only an occasionalswollen mitochondrion was seen. There were alsolarge vacuoles present which appeared to have con-tained lipid. Fine myofilaments were visible justbeneath the cell surface and occasional largerbundles were seen between the organelles of somecells (Fig. 5).At higher magnification these myofilament

bundles exhibited periodic densities indicating theirsimilarity to actin (Fig. 6). The cell surface tended tobe indistinct but no cell-cell or cell-stroma(hemidesmosomes on a basal lamina) junctions wereseen. Occasional groups of pinocytotic vesicles werevisible however (Fig. 7). Clefts frequently occurredbetween the collagen and the cells and betweenneighbouring cells (Fig. 4). These clefts were notbounded by a basement membrane and cell cyto-plasm rarely extended around their entire internal

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Smith, Pieterse, McClure

Fig. 1 Fibroma oftendonsheath with a collagenousstroma and constituentspindle and stellate cells.Haematoxylin and eosin x100.

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IFig. 2 The majority ofcells arespindle-shaped. Haematoxylin andeosin x 200.

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Fig. 3 Less frequent stellate cells are illustrated.Haematoxylin and eosin x 400.

circumference. No erythrocytes were seen in thesestructures.

Discussion

The clinical data were limited in this series but inagreement with the findings of Chung and Enzinger4

the lesion was more common in males than femalesand the fingers and hands were most commonlyaffected. The mean age in the present series was38 yr compared to a median of 31 yr in that ofChung and Enzinger. The mean diameter was19-0 mm compared to a median of 18.0 mm. Only inone case was there recurrence of the lesion (fivemonths after initial excision). This is considerablyless than the recurrence rate of 24% reported byChung and Enzinger but their series was muchlarger and follow-up was for a considerably longerperiod of time.

In determining the typical features of fibroma oftendon sheath it is evident that a collagenous stromagenerally containing spindle cells in a moderatedegree of cellularity were the dominant features.Blood vessels were fairly prominent in a majority

and in 80% an attachment to tendon sheath wasevident. Lobulation was observed in 70%. Foci ofstellate cells were observed in 60% of cases. Theserepresented the main diagnostic features and weresimilar to the criteria developed by Chung andEnzinger except that slit-like spaces were infrequentin the present series.

In a consideration of the differential diagnosis ofthese lesions one must exclude circumscribedfibromatosis, nodular fasciitis, neurofibroma,leiomyoma, scar tissue, giant cell tumour of tendonsheath (localised nodular tenosynovitis) and fibroushistiocytoma. Distinction from nodular fasciitis and

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Fig. 4 Spindle cells in acollagenous matrix (M)showing ovoid andconvoluted nuclei (N).Clefts are visible betweenthe cells and the collagen(C). x 1900.

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Fig. 5 Spindle cell with aconvoluted nucleus (N),rough endoplasmicreticulum (RER), vacuoles(V), and a thin band ofmyofiaments just beneaththe plasma membrane(arrows). x s400.

fibrous histiocytoma was relatively straightforwardsince myxoid change and extravasations of erythro-cytes (features of the former) and a storiform pat-tern (a feature of the latter) were inconspicuousfindings. In addition lesions were lobulated and notnodular. The circumscribed margins of the lesionstended to exclude fibromatosis. None of the lesionswas considered to exhibit sufficient evidence to sup-port the diagnosis of localised nodular tenosynovitis.Foam cells were never seen, siderophages were onlynoted in three cases and then infrequently and onlya few multinucleated giant cells were seen in one

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case. However the possibility must still be admittedthat the lesions denoted as fibroma of tendon sheathmight represent an endstage of a nodulartenosynovitis.The ultrastructural characteristics of fibroma of

tendon sheath have not been previously described.A study of two cases in the present series revealedidentical features. Ultrastructurally open cleftsoccurred between the collagen and cells and be-tween cells. These were considered probably to rep-resent the dilated slit-like vascular channels likenedby Chung and Enzinger to tenosynovial spaces.

Fig. 6 Higher power view ofmyofdlamentbundles (M) showing periodic densities(arrows). X 26200.

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Fibroma of tendon sheath

Fig. 7 Portion ofspindle cell showing roughendoplasmic reticulum (RER), myofilaments(M) and pinocytotic vesicles (arrows). x12 500.

From our studies it is evident that these spaces werenot vascular channels. There was no basementmembrane and often there was no cell cytoplasmbounding the edge of the collagen. The spaces weredevoid of red blood cells.

Of particular interest was the nature of the cellsobserved intrastructurally. Fibroblasts were seenrarely. These were elongated cells characterised by asmooth elongated nucleus, moderate to largeamounts of rough endoplasmic reticulum (oftendilated) and small numbers of other organellesincluding fine cytoplasmic filaments. The majority ofcells seen were myofibroblasts. These cells combinethe features of fibroblasts and smooth muscle cells.They exhibit nuclear indentations and folds, bundlesof intracytoplasmic microfilaments arranged parallelto the long axis of the cell and dense bodies similarto those in smooth muscle cells, surface differen-tiations with desmosomes and hemidesmosomes,abundant rough endoplasmic reticulum andpinocytotic vesicles.5

Myofibroblasts has been described in a variety oflesions. These include granulation tissue,5atheromatous plaques,6 ganglia,' hepatic cirrhosis,8triggering tenosynovitis,9 Dupuytren's contracture,'0desmoid fibromatosis,"I circumscribed fibromatosis'2and nodular fasciitis.'3As has been pointed out by Vasudev and Harris'4

few reports exist of myofibroblasts occurring in trueneoplasms. They refer to six documented cases ofmalignant tumours which contained myofibroblastsand which had been classified as fibrosarcomas.With regard to benign tumours nine cases of typicaldermatofibroma have been shown to containmyofibroblasts.'5 A giant cell fibroma of the oralmucosa has also been reported to containmyofibroblasts.'6 If it is accepted that fibroma of

tendon sheath is a true benign neoplasm then it is anexample of a tumour of myofibroblasts.The nature and significance of these cells have

been discussed by Ryan et a15 and Vasudev and Har-ris.'4 The former have suggested that myofibroblastsarise locally from more conventional fibroblasts orfrom primitive mesenchymal cells. Fibroblasts cul-tured in vitro develop intracytoplasmic fibrillar sys-tems similar to those of myofibroblasts.'7 Vasudevand Harris suggest that myofibroblasts represent theexpression of a limited potential in fibroblasts fordifferentiation along myoid lines and that thedevelopment of microfilaments is the normal reac-tion to a variety of proliferative stimuli.

We wish to thank Mrs L Murray and Miss R Noblewho prepared the EM sections and Mrs C Wick-remasuriya for typing the manuscript.

References

Buxton St JD. Tumours of tendon and tendon sheath. Br i Surg1923;10:469-74.

2 Alguacil-Garcia A, Unni KK, Goellner JR. Giant cell tumour oftendon sheath and pigmented villonodular synovitis: an ultra-structural study. Am J Clin Pathol 1978;69:6-7.

Geschickter CF, Copeland MM. Tumours ofbone. Philadelphia:JB Lippincott, 1949.

4Chung EB, Enzinger FM. Fibroma of tendon sheath. Cancer1979;44: 1945-54.

-'Ryan GB, Cliff WJ, Gabbiani G, Irle C, Montandon D, StatkovPR, Majno G. Myofibroblasts in human granulation tissue.Hum Pathol 1974;5:55-67.

' Geer JC. Fine structure of human aortic intimal thickening andfatty streaks. Lab Invest 1965;14:1764-83.

7Ghadially FN, Mehta PN. Multifunctional mesenchymal cellsresembling smooth muscle cells in ganglia of the wrist. AnnRheum Dis 1971;30:31-42.

Bhathal PS. Presence of modified fibroblasts in cirrhotic livers inman. Pathology 1972;4:139-44.

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'Madden JW. The contractile fibroblast. Plast Reconstr Surg1973;52:291-2.

0 Gabbiani G, Majno G. Dupuytren's contracture: fibroblast con-traction? An ultrastructural study. Am J Pathol 1972;66:131-46.

Stiller D, Katenkamp D. Cellular features in desmoidfibromatosis and well differentiated fibrosarcomas. An elec-tron microscopy study. Virchows Arch Pathol Anat Histol1975;367: 155-64.

2 Feiner H, Kaye GI. Ultrastructural evidence of myofibroblasts incircumscribed fibromatosis. Arch Pathol Lab Med 1976;100:265-8.

3 Wirman JA. Nodular fasciitis, a lesion of myofibroblasts. Anultrastructural study. Cancer 1976;38: 2378-89.


4 Vasudev KS, Harris M. A sarcoma of myofibroblasts. An ultra-structural study. Arch Pathol Lab Med 1978; 102:185-8.

5 Katenkamp D, Stiller D. Cellular composition of so-called der-matofibroma (histiocytoma cutis). Virchows Arch Pathol AnatHistol 1975;367:325-36.

16 Weathers DR, Campbell WG. Ultrastructure of giant cellfibroma of the oral mucosa. Oral Surg 1974;38:550-61.

" Goldberg B, Green H. An analysis of collagen secretion by estab-lished mouse fibroblast lines. J Cell Biol 1964;22:227-58.

Requests for reprints to: Dr J McClure, IMVS, Box 14Rundle Street PO, Adelaide, South Australia 5000.


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Fibromaof tendon sheath - BMJ