Leiomyosarcoma of Somatic Soft Tissues in Childhood: An lmmunohistochemical Analysis of Six Cases With Ultrastructural Correlation PAUL E. SWANSON, MD, MARK R. WICK, MD, AND LOUIS P. DEHNER, MD Leiomyosarcoma (LMS) of soft tissue is a rare tumor in children. Although LMS may exhibit clinical and histologic features that are typical of smooth muscle neoplasms in adults, they may often be confused with or resemble tumors of presumed fibroblastic, myofibroblastic, or rhabdomyoblastic differentiation. As a result, the diagnosis of LMS in children is often difficult to establish with confidence. To address this problem, we analyzed the immunohistocbemical features of six LMS in children (one of deep soft tissue of an extremity, one of paravertebral tissue, one of the retroperitomeum, two of oropharyngeal soft tissue, and one of subcutis); the ultrastructural features of four of these tumors were also Istudied. Histologically, each of the three tumors of deep soft tissue and one of the retromolar trigone were composed of pleomorphic spindle cells arranged in interweaving fascicles. In contrast, the subcutaneous tumor and the lesion of the hard palate had an epithelioid appearance. Ultrastructural features were typical of adult type LMS. Immunohistochemically, these neoplasms were diffusely reactive for vimentin, while each was negative for cytokeratin, epithelial membrane antigen, and S-100 protein. Desmin was present in all cases, but was expressed only focally in three: a similar pattern of staining was noted for muscle-specifimc actin. although staining was generally noted in a larger population of cells. a-1-Antichymotrypsin was found in five tumors, and cathepsin B reactivity was encountered in four cases. Leu-7 antigen and myelin basic protein were coexpressed by one tumor, but neither was found in the remaining cases. These results indicate that immunobistochemical detection of desmin and muscle-specific actin may be useful in the differential diagnosis of spindle or epithelioid cell proliferations in childhood when ultrastructural analysis is unavailable. HCM PATHOL 22:569-577. Copyright i 1991 by W.B. Saunders Company I,eiotn~~~s~il-~oni~i (LhlS) is ;I r;trc nt~~pl~srn in c~hildhooci. ant1 2s ;I prirriar\. nialignartc~~ ot sof‘l tiasues in this age group, it is tweedingly u~~o~i~~i~on. ‘-; At lclzst SOIW c ;tses reported as LbIS, especially those nlaj reprcwmt twimples ot tlia~gtiosccl it1 neo1i;ttes, ~ongenit;il-iirt~ttitil~ ~ri\ofil)l-onlatosis with au excel-

_---

569

HUMANPATHOLOGY TABLE 1.

lmmunohistochemical This Study

Reagents Used in

sour< c

Keagellt

Volume 22, No. 6 (June 1991)

Diluuon

Monoclonal anttbodirs Cptokeratin* AElIAE3 I : IO0

hlAii 6 I:Xl)

Vmentin

(\‘9) I:? Pwdilutcd

Desmin Muscle-apecilic actin (HHF1.5) Mvoglobin Eplthelial mrmbran~ antigen (ES) Leu-7 antigen

I: 11’.000

I:xoIl

t :H(I

Pol~clonal antibodies S- 100 protein hlyelin basic protein a-l-Antichymotr~pain Cathepsin Bt Other reagents Sheep anti-I-ahhit globulins. biotinylatrd Sheep anti-sheep globulins. hmtm~lated Horse anti-mouse globulin. hiotinvldtcd Avidin-bwtin peroxidase complrv Rabbit anwmousc globulins Mouse peroxidaseanuperoxidase romplr>

t .liilO 1mo 1: I ,L’CI(I I :800 f is II 2s” I :-II) I :L’oo

* AEl/AES and hlAIGti used together a? .* cvtohct-atin “cocktall” tit the stated diluuons. t Sheep heteroantiswum $ Kabhit VectaStain ABC: lGt\. 8 Sheep VectaStain ABC: Kits flblouse VertaStain ABC: Kits.

RESULTS

Light Microscopic Features

Clinical Features

‘I-he histologic appearances of the six cases in this series were relativelv diverse, but shared areas in which elongated or iusiform cells were arranged in interweaving fascicles (Fig 1. left). Although it was noted in areas of cases IIO. 1, .?. and 6, cellular pleomorphism was not marked, nor were tumoral giant cells encountered. Mitotic activity was apparent in all tumors (Fig 1, right), but did not exceed eight division figures per 10 high-power fields. In three cases (cases no. 2. 3, and 4). the microscopic appearance was nodular; in each instance, demarcation from adjacent stromal was abrupt, with pushing margins. In

The pertinent clinical features of each case are summarized in Table 2. Patients (two males and four females) ranged in age from 8 months to 18 years at diagnosis. Two tumors involved soft tissues of the oropharynx, and one neoplasm each arvse in the following locations: paraspinal soft tissues, retroperitoneum, extensor compartment of the upper leg, and subcutis (deep dermis) of the lip. With the exception of case no. 3, all lesions were excised; however, location in the oropharynx precluded complete surgical extirpation of tumors in cases no. 5 and 6. Local raTABLE2. Age&x

Size (cm)

I 2 3

21 ma/M 8 trio/F 14 yr/M

>5.0 2.4 1.1

4 5 ti

I5 y/F 9 yrlF 18 yr/F

Case No.

diation therapy was administered in case no. 2 (5,200 rad) and case no. 3 (3,000 rad), and multiagent chemotherapy was given in cases no. 1 and 3. Because most cases were referred in consultation, clinical follow-up was incomplete in some instances. In case no. 1, a large soft tissue mass was resected from the anterior thigh. Despite adjuvant chemotherapy, the child died with disease 18 months later. In case no. 4. a subcuticular-deep dermal lesion was removed surgically, without recurrence or metastasis in the 12 months following diagnosis. Of’ the two children treated at the University of Minnesota, one (case no. 2) was free of disease 96 months after diagnosis. The other child presented in an unusual fashion and suffered a rapid progression of disease despite aggressive therapy. In this case (case no. 3). the patient, who was a l+year-old male, was the recipient of a renal allograft (cadaveric) 3 years earlier for chronic renal failure secondary to renal dysplasia. He had been treated with cyclosporin A, anti,md OKT3 for two episodes of lymphocyte globulin, L acute rejection. ‘I‘his child underwent a laparotomy to evaluate the cause of acute abdominal pain 5 days after the implantation of a second cadaveric renal al‘I 0.5cm nodule was noted at the lografi. At surgery, L ligament of Treitz, a biopsy of which demonstrated low-grade LMS. No obvious organ-associated or retroperitoneal 111ass was identified. Subsequent clinical evaluation revealed multiple hepatic and splenic metastases. Chemotherapy was complicated by the need for immunosuppression for maintenance of his allograft, and there was a poor response to radiotherapy. The child suffered progression of intraabdominal disease and died 10 months later. An autopsy was not performed.

Abbreviations:

Location Anterior thigh Paravertebral ?Retroperitoneal Lip-subcutaneous Retromolar trigonr Hard palate

0.x 2.3 2.0

NED. no evidence

Leiomyosarcoma in Childhood: Clinical Features

of turnor;

DWD, &ad

with disease.

570

Trrattnent

Follow-up

Excision cbemotherap~ Excision. 5,L’OO mcl Biopsv, ch~motl~erapv. Y.000 rad Excision Partial excision Pnrtial excision

DWDi 18 tno .NEDI”G tno Liver and spleen metastasis at diagnosis, DWD/IO nw NED/I :! mo Not available Not available

LEIOMYOSARCOMA IN CHILDREN [Swanson et al)

FIGURE 1. Leiomyosarcoma. (Left) Spindled cells in case no. 1 form interweaving foscicles. (Hematoxylin-eosin stain, magnification x 200.) r 3501 (Right) Mitotic activity was apparent. (Hematoxylin-eosln stain; magnkation

plastic cells iti a nianncr tilage (Fig 3. right).

rentinicc~tnt

of Iicoplastic

car-

Ultrastructural Features E:lrc.tI.on microscopic, examination was pertormed in fi~ut- cases (cases no. 2 through 4 and 6). In each rsaniple, the tumor w2s dominatecl by tusiform (cxses no. 2 and 3) or polyynal culls (c.as& no. 4 and 61 Ihat Cotitained it-regularly indented oval nuclei. (~hromatin was coarsely granular, tixallv tnarginated, and cxxxiotiatty assoc.iatecl with w,vell-iormed small nucleoli. ‘I‘he cytoplasm invariabt\~ contained skeins of nlic-i.ofit;tnlerlts interrupted spc;radically by dense hodies. I’inocytotic vesicles wet-e evident in three examples (cascs’no. 3, 4, and 6). Ptasntalett~n~a! ptacques \~‘ere notes! in each tumor. and discotttinuous basement metnbrane material was variable present (Fig 4). In (~tst‘ no. 2, tumor cells c~c,nta’itted moderate amounts 01 rough endoplasmic retic.u!um, whereas III other examthis sIi-uindle cells. Small portions of thr lesion in case t10. I wew foci iti \vttich a hcmanc.haractet-iced b\ hypocellulal#ioperic~toiii;l-like \xcular pattern was cc~nspicuous (Fig 3. kf’t). ,4diacent lo these artxts, nivsoid stroma supporlcd s~iiall lt11iior trtl clusters or ‘iscllatet! nc’o-

lmmunohistochemical

Features

‘1 he itrrntt~~lopllenotyl,e ot eac,tt case is !)resented in ‘I‘able 3. Regardless of‘ the major cell type (spindled ot- epithetioid), the majoritv oi tumor cells in each case were stron~ty re&tiv& for vitnwtin. Desmin!)ositive ncc)!kisnc cells were also f’oultrl (Fig 5) in al! 571

HUMAN PATHOLOGY

FIGURE 2. Leiomyosarcoma. Epithelioid cells predominated case no. 4. (Hematoxyin-eosin stain; magnification x 500.)

Volume 22, No. 6 [June 19911

12 cases with only one extravisceral example.“’ Several larger series of soft tissue sarcomas in children have revealed that LMS probably represents less than 1% of all soft tissue malignancies in this age A review of the available literature group. 1.L’.4~5.‘Lx~p!’ reveals a total of 28 examples of soft tissue sarcomas in childhood that have been sufficiently well documented to warrant consideration as LMS (Table 3). Inclusive of the present series. a female predominance was apparent (21 females: 12 males), with the age at diagnosis ranging from newborn to 17 years (mean. 8.2 years). Most tumors arose in the head and neck region,‘:! extremities,* or axialiparavertebral soft tissues.” Primary thoracic (two) and retroperitoneal (three) lesions were considerably less common. Seven neoplasms arose in the dermis or subcutis, and two principally involved the wall of the femoral vein. In those cases with adequate clinical follow-up. 17 patients (59%) remained free of disease after resection or ad_juvant therapy from 6 months to 9 years after diagnosis (mean, 4.9 years). .Two (7%:) were alive with persistent or recurrent disease at 2 and 12 years, and the remaining 10 (35%) died of their tumors at 10 months to 22 years (mean, 5.0 years). Apart from primary cutaneous lesions, in which cases all patients were free of disease or died of other causes, no site was associated with a prognosis that deviated substantially from the series as a whole. Overall, age had no apparent effect on clinical outcome; however, when cutaneous lesions were excluded from consideration, tumors occurring in children less than 5 years of age were generall), less aggressive. Only three of nine such patients died of disease, compared with two of five patients aged 5 to 10 years, and five of eight children older than 10 years. ‘I‘hese results roughly parallel the experience with LMS in adults . 3IL’-14.I X.2I .J!S--82although the overall survival rate for this sarcoma may be somewhat higher among the children. Notably, most cutaneous lesions at all ages behave in an indolent fashion, although the occurrence of lymph nodal or soft tissue metastasis in two reported examples”‘.:‘x emphasizes the aggressive potential of these peripherally disposed lesions. ‘I’he current series of six neoplasms closely mirrors the combined experience recounted here, but also raises the important issue of immunologic surveillance in the histogenesis of soft tissue sarcoma. The potential exists for the induction of malignancy in the immunocompromised or immunomodulated host,+:‘-“” and one previously reported case of LMS in childhood developed in this setting.4G ‘I-he occurrence of a highly aggressive retroperitoneal LMS in a child immunosuppressed for maintanence of a renal allograft represents an intriguing addition to this phenomenon. From a diagnostic point of view, the neoplasms in the present series displayed a histologic spectrum which invokes several differential diagnostic considerations. Perhaps most important in this context is the recognition of various clinically indolent myofibroblastic proliferations, including the so-called fibro-

in

instances, although reactivity was focal in cases no. 1, 3, and 6. Monoclonal antibody to “muscle-specific” actin similarly labeled all six lesions (Fig 6). but cases no. 1 and 6 were stained in a focal manner. Keactivity for these myogenic determinants was most obvious in densely cellular areas. Overall, actin positivity was more consistently observed. In the hemangiopericytoma-like foci of case no. 1. neither desmin nor actin reactivity was identified. Myoglobin was not detected in any example. Leu-7 labeled occasional cells in case no. 1, but was uniformly nonreactive with other tumors. A similar distributibn of staining was noted with antibodies to myelin basic protein. S-100 protein was not apparent in any tumor studied. Of the proteolytic enzymes that were assessed, CY-1-antichymotrypsin was most commonly expressed (five neoplasms). whereas cathepsin B reactivity was apparent in four tumors. Neither cytokeratin nor epithelial membrane antigen was identified in any lesion. All positive and negative controls stained appropriately. DISCUSSION Leiomyosarcoma is a rare neoplasm in children in general, and even less commonly presents primarily in soft tissue, as demonstrated in a recent series of 572

LEIOMYOSARCOMA IN CHILDREN [Swanson et al)

FIGURE 3. Unusual histologic patterns in lelomyosarcoma. (Left) Case no. 1 exhibited varyng “nonmyogenlc” patterns. Including areas resembling hemangiopencytoma. (Hematoxylin-eosin stain; magnification x 60.) [Right) Also seen in case no. 1 were areas in which a chondroid-like matrix was elaborated. IHemotoxvln-eosin stain: magnification J 350.1 In each area, however, lmmunohistochemistry revealed a “myogenlc” phenotype (see iext].

titx otii;itosis.

s;trcoma-like r.ounteref:l

in

ctlildrul.

\oung

the

detfp

‘.x..‘X ‘l‘he

which soft

is tiiost

tissues

tieoplasms

of iri

often int;tnts ~‘2x3

en-

hrous histiocvtoma. cral Ilt’t‘vc sheath

;ind 110.

c~1101ld1-0a~1r-c

I

noses

2

t-eprrwnt

taxamples

were

olll;is.:~.‘i

Ititieetl.

tlir

tatter

tb’o

diag-

c~otisidrred during the- pwliminarv evaliiation of this lesion. because it had ;t \~aguel~~ chondroid character foc;illy, and showed permt&ion ot adjacent skeletal muscle that imparted an appearance su&eativv of heterotogous nivo,genic differentiation. actin ‘I‘he unifortnity of reactivit\. tj,*- muscle-specific and desmin in this lesion. to thv exclusion of other determinants, provided coticlusiw tv idence of its tiiyogrnic nature. rhal~dt~myo~at-coma, On occasion. a11 embr\onal epeciatl!, from the parate&utar region. ha a predominant spindle cell pattrrn; howevctr, eosinophilic rhat~tiom~ot~l~sts art‘ often intwsperstd among the spindle c,elts or the presence 0L cvtoptasmic crossstriation helps facilitate thy diagnosis of rhabdomyosarcoma. Kale et al have discussed their experience bvith spindled embr):onal rhabdomvosarc~om~~ and the fnm L,MS.t’ Ohvidift‘icult~~ powx1 by tts distinction ousl~. both therapeutic and prognostit purposes are served by the separation of these t\vo myogenic neoplasms. ‘l‘hv usefttlness of c-lectron micrckopy in this setting was demonstrated in t’our of our cases, each showing features of‘ smooth muscle differentiation. In further contrast to spindled rhal)c-lomyosarcoI~l~1.

LRIS that twembled such lesions. wherein compact fusiform or owid cells were focal,ly ;Irranged in haphazard fkictes. C&e no. L’ was diffic.titt to separate from t‘il)robtaati~-In,c,tibroblast.ic lesions because of the relative uniforn;it\ of its cellular pq)ulation. However, in this neoplasti~. rIltrastruc:t~lri~t features of smooth muscle differentiation were detinitet) present. In contrast, ;I lesion of the rrtrornotar trigc;Ite (case no. 5) assumed ;I variabl\ cellular apprarance punctuated by weas of tibrosis and stromat mwom;itous degeneration. ant1 thus SIIperticiall\ res&nbled lesions otherwiw categorized as Gther t~i~ofil~roiiiatosis or fasciitis. ‘l‘hew features were non&hrttx accompanied by overt c~ytotogic at!cytopia. brisk niitotic. activity, fibrillar eosinophilic plasm. and focaltv fascicular growth. Other soft t&sue neoplasms also were mimickrd t)y lesions in this series. For instance. in selected areas of case no. 1. ;I tocall\- infiltrative pattern of compact bv ;I hemangioperispindled cells M’X accompanied and thus resembled cytoma-like vascxlar pattern. “monophasit ” svnoviat sarcoma. ‘I‘his pattern mav be seen in .I variety of other soft tissue neoplasms: itlc.luding l~‘it~ros~ii~c~otn;~-til\efibromatos~s. malignant fi-

and

liposarcoma, malignant periph;rtid ti~eserictiyn~at tumors,

of

573

HUl’v!AN PATHOLOGY Volume 22, No. 6 (June 1991)

FIGURE 4. Ultrastructure in leiomyosarcoma. In ultrathin sections of case no. 3, skeins of microfilaments are interrupted by dense bodies. Subplasmalemmal placques are evident, and micropinocytotic activity is conspicuous. Basal lamina is present. (Uronyl acetate/lead citrate; magnification x 32,260.)

each of the six cases reported herein was immunohistochemically nonreactive for myoglobin. Based on the foregoing discussion, the general conclusion that can be drawn from this study is that the accurate diagnosis of childhood LMS depends in large part on ultrastructural and immunohistochemical evaluation. Since electron microscopic analysis may not be practical, or possible, in all cases, one may question whether immunohistochemical studies are sufficient to verify the smooth muscle nature of a soft tissue tumor, especially in light of the aforemen-

TABLE3.

tioned spindle cell embryonal rhabdomyosarcoma. Our goal, based on a similar study of LMS in adults,2s was to determine the immunophenotype of these lesions in children using ultrastructurally defined tumors as a standard for comparison. Our earlier study, which has been corroborated by other authors, indicated that a combination of antibodies to desmin and muscle-specific actin was a reliable method of verifyneoing myogenic differentiation in such plasnls,“5,-l”-.5”

‘I‘his conclusion

VIM

DES

ACT

MI’0

LCU-7

s- 100

MBI’

1 2 3 ‘I 5 6

+ + + + + +

1+ f1

f+ + + +

0 0 0 0 0 0

+ 0 0 0 0 0

0 IJ 0 0 0 I)

+ 0 0 II 0 0

1:

to be warranted

hr

pe-

Leiomyosarcoma in Childhood: lmmunohistochemistry

Case No.

+

appears

AA(;I‘ + + + + + (I