Ovarian involvement by the intra-abdominal desmoplastic small round cell tumor with divergent differentiation: A report of three cases

Ovarian Involvement by the IntraAbdominal Desmoplastic Small Round Cell Tumor With Divergent Differentiation: A Report of Three Cases ROBERT H. YOUNG, MD, JOHN H. EICHHORN, MD, G, RICHARD DICKERSIN, MD, AND ROBERT E. SCULLY, Three girls, one 14 and two 15 years of age, with the recently described neoplasm that has been designated “intra-abdominal desmoplastic small round cell tumor with divergent differentiation,” and ovarian involvement at presentation are described. In two cases the ovarian tumor was initially thought to be the primary neoplasm. In all cases there was extensive extraovarian tumor at the time of presentation. The ovarian involvement was bilateral in two cases and unilateral in the third. Microscopic examination showed prominent nodular growth within the ovaries. The tumors were characterized predominantly by nests of small cells with hyperchromatic nuclei and scant cytoplasm separated by a prominent desmoplastic stroma. A few tubules containing mutinous secretion were present in one case. On immunohistochemical staining many of the tumor cells stained positively for cytokeratin, epithelial membrane antigen, desmin, and vimentin. Staining for neuron-specific enolase was present in two cases but was conspicuous in only one of them. Leu7 was expressed by the tumor cells in two cases, and S-100 protein by one, giving further support to the possibility of neuroectodermal differentiation within some of these neoplasms. The two cases studied by electron microscopy both showed frequent intercellular junctions, basal lamina, cytoplasmic filaments, and sparse, small dense granules of either neuroendocrine or lysosomal type. Paranuclear aggregates of filaments were found in one case and cellular processes were prominent in the other case. The differential diagnosis in these cases was extensive and included a number of small cell tumors that may involve the ovary, either primarily or secondarily, in young females. The desmoplastic small round cell tumor should be considered in such cases when the appearances on routine examination are consistent with the diagnosis, and ap propriate immunohistochemical stains should be performed to confirm the diagnosis. HUM PATHOL 23:454-464. Copyright 0 1992 by W.B. Saunders Company

A few years ago, two of us (R.H.Y. and R.E.S.) reported two cases of alveolar rhabdomyosarcoma that had metastasized to the ovary, and presented a discussion of the differential diagnosis of small cell malignant tumors of the ovary.’ Since that time, our experience has indicated that the already large number of tumors that must be considered in these cases includes several additional neoplasms not mentioned in that discussion. One of them, malignant melanoma metastatic to the

From the Department of Pathology, Harvard Medical School, and the James Homer Wright Pathology Laboratories of the Massachusetts General Hospital, Boston, MA. Accepted for publication October 4. 1991. K
MD

has been the subject of a recent publication.’ Another is the subject of this study, which was prompted by the recent observation of prominent ovarian involvement in two young girls with widespread small cell malignant tumors that had the microscopic features of the tumor recently described as “intra-abdominal desmoplastic small round cell tumor” (DSRCT).“.* This experience led us to re-evaluate a case we had seen several years ago of a small cell malignant tumor with prominent ovarian involvement. Examination of routinely stained slides of the tumor in that case, and in the other cases, showed features characteristic of this neoplasm, and the diagnosis was supported by appropriate immunohistochemical results. In this report we record the clinical and pathologic features of these cases and contrast their pathologic features with those of other small cell malignant tumors that may involve the ovary. ovary,

MATERIALS

AND METHODS

The three cases were retrieved from the consultation filrs of one of us (R.E.S.). Hematoxylin-eosin-stained slides were reviewed in each case. For case no. 1 (SCS 10 144), 16 sections were available, and three representative tissue blocks were obtained. For case no. 2 (SC91 147). 33 sections of the primary tumor and three of the recurrent tumors were available, as well as nonembedded, formalin-fixed tissue. For case no. 3 (SCS22512), 25 sections were available. as well as formalinfixed tissue. One section from case no. 3 was stained with mucicarmine, periodic acid-Schiff; and periodic acid-Schiff with diastase. Immunoperoxidase stains (avidin-biotin-peroxidase complex method) were done on representative tissue from all three cases. with the use of the antibodies and dilutions listed in Table 1. In cases no. 2 and 3, electron microscopy was performed on nonembedded, formalin-fixed tissue that was washed in sodium cacodylate buffer and reprocessed with Karnovsky’s II solution, postfixed in 2% osmium tetroxide, stained en bloc with uranyl acetate. dehydrated in graded ethanols, infiltrated with propylene oxide/Epon, and embedded in Epon. One micrometer-thick sections were cut, stained in toluidine blue solution, and examined by light microscopy. Representative areas were chosen for thin sectioning, and the resulting sections were examined in a Philips 301 electron microscope.

Case Histories Case No. I (SCSlO144~. A 15-year-old girl with a short history of constipation and edema of the right leg underwent a laparotomy. which disclosed large bilateral ovarian tumors and tumor in the omentum and mesentery. A bilateral salpingooophorectomy was performed and omentum and mesentery

454

DESMOPLASTIC

SMALL CELL TUMOR (Young et al)

TABLE 1. Commercial Sources of Antibodies

Hvhritrt h, lnc (Sari Diego. (:A) Be~torr-I)i~kinhon (Mount;lin View, (I;\) 1)akoPatts (:o. Irrt (C:;tr-pintcr-ia.(:A) Biomedical ‘I‘echnologirs. 111~(Stoughtotr. \I 22I Becton-l)i~kinrc,n 1)akol’atts <:o. In< Dakol’atta (.o. III< 1)akol’atts (:o. Inc E:rr~oIXagnostic-s. 111~(New \‘III-k. NY) Sigma Cllrmic aI (:() (St I .ouis, hl( )) Bc~ton-I)i~kiiis(,n I);tkol’atts (:o F.n~o I)iagnostic5, In, I)akoP
ttintot ~crt’ also rrsrc~trd. The patient was rdcarr-etl to artothct. irtstitrttion. where ;I se~oncl oper;Ition tlinclosecl ;I 3) Y L’x I( 20 ctti tumor estencling from 7 ciii atxw thr anal vtqv along ~hc cul-de-WC, sacrrmi. and left pericolic space to silt-round ttlc* ret IIII~, sigmoid colon, and transverse c,olon and h)th urctcm. The patient underwent hystcrectoni\- with rcwc.tion of ttrc. WC tttm. sigmoid colon, and rx~r~oval of as much 01 the pelvic ;md ahclominal tumor as was techrricAlv feasiblr. c cbnt,iitting

‘l‘hr patient RY c%ivcd comhinatiorr chemother-spy, ‘including (.ispl;ttin po~top~rativc+y. but died -1 months Iatcr-. (,‘(I.sPh’o. 2 (.s‘C.Z’I 14 7). A I 5year-old girl who presented with abdoniin~~l distension was rioted on physical esaniination IO havr a large pelvic mass and an enlarged left-sided cervical lymph node. She had begun menstruating at 13 yrars of age, aid had regular periods uritil approximately 5 months prior

IO presenration, at which time her menses ceased. An abdomirral computeri~cd toiiiogrdphic scan showed enlarged I‘etr’op(+toneal nodes. .4 biopsy of rhe cervical lymph node suggcstrd riietastatit c-nrrinoma on frozen section evaluation, and ;t lapawtcmn was performed. The operative findings included ;I I.5 X 1 1 :c H CIII right ovarian mass, a left ovarian mass 9 ~111 itr greatest dimension, and multiple serosal and omental nodtries, up to 3 c 111in gratest dimension. A second-look lapar-ototn); performed 7 months later revealed persistent trmior cstrnsivcly invohing scrosal surfaces. A total hysterrc,tomy was tlren perfor-mrd, with biopsies of numerous abdominal ad ptalvic nodulrs. rhis case is recent.

(,?I.wR’o. i (SCS225 12). A I&year-old girl who had lost II) pounds over. a 3-month period presented with signs anti SL tnptoms of an acute abdominal disorder. L!ltrasound showed ;t pelvic IIMSSand laparotomy disclosed a pelvic tumor, a boss&ted enl;lrged right ovary. multiple nodules of tumor in the omentrmr, and ;I nodule oi tumor on the uterus. l‘he patient rmdcrwent ;I right oophorectomy with resection of the pelvic turrlot- and thr trrnror on the uterus and a11ornentet tomy. This C.
I : 100 I :5 I :30 NIXI I A0 I :750 I:10 I : IO0 ix’cat I :“.wo

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dominantly of solid, lohulated, cream-colored tissue, but a few qrsts up to 1 cm in diameter were present as well. ‘l’he mrsentery aud omen~um wcrc studded with numerous tumor nodules ranging fro111 trncler I IO 2.5 cn~ in diameter. The peric-olic tissue from 1l1e second operation contained many confluent, ran-lvhite, nodular tumor masses. The colonic mucosa was unrentarkable. Separate masses of similar turnor from other areas in the pelvis and lower abdomen were alsco receilred. The uterus appeared normal. The right ovarian mass iI1 c‘ast* no. 2 nleasured 15 X 1 1 X 8 cm and weighed 750 g. A tense unilocular c>\~I containing bloody fluid ac.c.ount~d li)r tM.0 thirds of the mass, while the remaining third was solid, 1x1. and multilchulated, with small stellate I;)ci 01. lieni01-rhage. The left ovarian mass, which measured 9 cm in greatest dimension and weighed 2HO g, ~vas entirely solid. ~nultilobulated. and tan. ,4 compressed wedge olovariau parenchyma contained follicle cysts. rtle multiple omental and peritoneal nodules, taken from the abdominal wall and sigmoid serosa, were s( #Iid a11d tan. The right ovary in case no. 3 me;lsurecl 5.3 X showed a 3.!) X :3.6 cm and weighed 25 g. Sectioning tan, soft tumor 6.4 cm in greatest dimension. The pelvic tunlor was bosselated, measured 7.8 X 3.0 X 3.6 cm, and weighed 42 g. Sectioning showed a homogeneous tan mass. Thcs omentum contained manv tmrlor nodules ranging from a few millimeters to 3.2 cm in diameter: they were soft and tan or yellow-tan. The uterine tumor measured 2.!) cm and was tan with focal cystic. degencration. Microscopic

Features

The microscopic features of the thl-cc casts were strikingly similar. Low-power microscopic examination of the ovarian turllors showed discrete nodules and sharply circumscribed aggregates of cells with an epithelial appearance separated by dense fibrous stroma (Fig 1). which was conspicuous in most areas. The ag-

RESULTS Gross Pathology The ovarian tumors in case no. 1 were !I cm and 8.5 cm in greatest dimension. Both were composed pre455

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HUMAN PATHOLOGY

lmmunohistochemical

Features

The inlmunohistologic profiles of the three tumors in this series are summarized in Table 2. In each case staining of tumor cells for keratins and for epithelial membrane antigen was widespread and intense (Fig 7). Paranuclear globular staining of turnor cells for desmin (Fig 8) and vimentin was also noted in each case, but the distribution varied from rare, scattered cells (case no. 2) to large foci (cases no. 1 and 3). In addition, most tumor cells in case no. 2 showed granular cytoplasmic vimentin staining. In this case staining of some tumor cells for actin was also noted with the use of two antibodies. Kare Leu-M 1 -positive cells were noted in each case, and rare B72.3-positive cells were found in cases no. 2 and 3. Leu-7 was expressed by most of the cells in case no. 2 and some of them in case no. 3, and neuron-specific enolase was detected in rare to many cells in cases no. 1 and 3, respectively. No staining fo1 carcinoembryonic antigen, melanoma antigen HMB45. chromogranin A. neurofilament, glial fibrillary acidic protein, or synaptophysin was noted in any case.

Ultrastructural

Features

Both neoplasms examined were composed of islands of small cells surrounded by basal lamina (Fig 9). The cells were in close contact with one another and

FIGURE 1. Nests of cells with peripheral palisading are present within a fibrous stroma. (Hematoxylin-eosin stain; magnification x 125.)

gregates ranged from tiny clusters and slender trabeculae (Fig 2) to rounded and irregularly shaped islands that often coalesced. Central necrosis was evident in larger islands (Fig 3) and there were a few spaces containing eosinophilic fluid in the center of nests in one case. There was peripheral palisading of basaloid cells in some of the nests (Fig 1). In minor foci in case no. 3 and large regions in case no. 2, the tumor cells acquired considerable eosinophilic cytoplasm and were fusiform or spindle shaped (Fig 4)) creating in areas an appearance of a biphasic pattern (Fig 5) because rounded cells with scanty cytoplasm were adjacent to more spindleshaped cells with appreciable cytoplasm. In case no. 3, rare tubules lined by cuboidal tumor cells (Fig 6) were present with intraluminal basophilic material that stained positively with mucicarmine and periodic acidSchiff. The stromal component varied in cellularity, but was mostly densely collagenous with minor myxoid areas. High-power microscopic examination of the cellular foci showed a preponderance of cells with indistinct cytoplasmic borders and oval, slightly convoluted hyperchromatic nuclei with irregularly clumped chromatin and one to three small nucleoli. Mitotic figures were frequent. In case no. 3, luteinization of ovarian stromal cells was present adjacent to the tumor. In each case, foci of residual ovarian parenchyma were identified. The above description is based on the appearance of the ovarian tumors, but we did not notice any differences in the appearance of extraovarian tumors. 456

FIGURE 2. Cords of cells with hyperchromatic nuclei and scant cytoplasm are present within a fibrous stroma. (Hematoxylineosin stain; magnification X313.)

DESMOPLASTIC

SMALL CELL TUMOR (Young et al)

DISCUSSION The clinical. gross, routine m~roscc~pic, immunohistochemical. and ultrastruc.turaI featurcbs of the three tumors we have reported arc consisten[ with the neoplasm first described in the litc~rature in two independent reports in 1989”~” and designated “inrra-a~~clominal desmoplastic small round cell tumc)r” in the largest reported series.’ Only six of the 26 previously reported tumors of this type have occurred in fen~alt3.“~R i2ltllOLl~tl ovarian involvement is not specifically men(ioned in an) of these reports, our observation of three cases with significant ovarian involvement suggests that when this tumor does occur in females, ovarian involvement is often present. This is not surprising since there is typically extensive involvement of the peritoneum bv a high’ly malignant tumor with a predilection for the pelvicOur experience with the (XSCS described region.i here has caused us to add this entity to thr already long list of neoplasms that one has to consider in the differential diagnosis of small cell malignant tumors involving the ovarv.’ As in all of the previously reported cases of this neoplasm. the three examples reported here occurred patients. Except for the invol\.ement of tht in young ovarv and the presentation in two of the patients as ovarian cancers, the clinical features and distribution of the tumors did not appear to diff’el- from those CIIFIGURE 3. Necrosis is present within a large nest of tumor cells. (Hematoxylin-eosin stain; magnification X 125.)

11,d numeI-oils

ilit~1-iliettiate,j~l~l~tions

and desnIoson~es

(Fig 10). III ~‘ase no. 3 there were also foci of radially arranged IlighC,jimr.tions ~trid,junctiorlal complexes, suggesting rag-ly Itmien f’ormation, but no actual luminal spa(~s will1 microvilli were identified (Fig 11). In case IIO. 3 rhe ~cells were uniformly round and oval, and had finely dispersrd chromatin and frequent large and multiple nucleoli (Fig 12). The nuclear to cytoplasmic ratio was high ~II both tumors. The cytoplasm was extended illto polar- processes in many cells in case no. 2 (Fig lo), 1,111this featlirc. was less (‘oninion in case no. 3. Occasional mic~rotubules were found in case no. 2. and occ,lsional sulall, dense c’ore-type granules were found in processes and ~11 bodies in both tumors. In both cases, Illicl.otilaInents were present in ;I moderate number of in a few cells. Rare cells md in heav), concentrations cells in case no. Z-5had paranuclear clusters of intermediate fila~nents (Fig 12). Otherwise, the cytoplasm of the cells (11 both tumors was generally similar, having a background of free ribosomes and a moderate number 01‘ mitochondria and cisternae of rough endoplasmic number of lipid reliculum. In case no. 2. a moderate neoplastic cells droplets vvcw present in well-preserved (Fig 9). C,Iycogen was not conspicuous in either case. The matrix between the islands of tlmlor cells in both c,~ses consisted predominantly of banded collagen (Figs !J and 101 with interspersed fibroblasts and myofibrohlasls.

FIGURE 4. Tumor cells, some of them spindle-shaped, with appreciable cytoplasm. (Hematoxylin-eosin stain: magnification X310.)

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I

i ’ I

FIGURE 5. Alternating areas in which the cells have either scanty or more abundant cytoplasm impart a biphasic appearance. (Hematoxylin-eosin stain; magnification X200.)

I

countered in other cases. On microscopic examination the appearance of the neoplasms was typical of that described in the literature. An unusual feature of one of our cases was the presence of small tubules containing mutinous secretion, but tubules have been described rarely ir, this neoplasm by other investigators.4.“a7 In all of our cases we obtained the typical immunohistochemical results, with many of the neoplastic cells staining for cytokeratin, epithelial membrane antigen, desmin,

and vimentin (Table 2). Paranuclear globular staining for desmin, reported to be an important characteristic of this neoplasm, was present in all three cases, but was often focally distributed, and in case no. 2 was present in only rare tumor cells. Expression of desmin by only a minority of the tumor cells in some cases has been mentioned in the literature.” It is also noteworthy that in the case in our series with only focal stain&g for desmin, actin positivity was also present. Less conspic-

FIGURE 6. A few small tubules containing scant mutinous secretion (arrows) are lined by cuboidal tumor cells. (Hematoxylin-eosin stain; magnification X313.)

458

DESMOPLASTIC SMALL CELL TUMOR (Young et al) TABLE 2.

Results of lmmunohistologic

uo115 i~~~~lll~tioIiisto(.ht‘~iii~.;~l staining of the tumor fi)~ Il~ul.on-spc,c.itic. enolase in our cases is also cxmsistenl witli the di:igricAs.“mh Staining for Leu-7, present in two of’ our ( asty UYISalso noted in the one other series in whi~~ti scailiing fi)r this antigen was performed.” SirnuL tanrotls positi\ity for chr-oniogranin reported in that

FIGURE 7.

Stains

st%es,” however. was lacking in our c;tst’5,. I,eu-‘7, likr nelu-on-sl_‘e~ific. anolase, is often positive in tumors with presumed neuroectociermal or ri~ul~oentlo~ririe differentiation.!’ More specific markers of‘ nelIroectodermal differentiation, including @al fihr-ilIar)- ;Icidic- protein, neurofilanrent, and synaptophysin, were not drnlonstrated in the present series. The possibility that the

Intense staining of the tumor cells for cytokeratin stain for CAM 5.2: magnifica-

CAM 5.2 (lmmunohistochemical tion x 313.)

459

FIGURE 8. Globular staining of tumor cells for desmin. (lmmu nohistochemicat stain for desmin: magnification ‘~313.)

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HUMAN PATHOLOGY

FIGURE 9. Neoplastic cells are small, closely opposed, and arranged in islands in a matrix of collagen. Nuclei are pleomorphic and heterachromatic. The cytoplasm contains a moderate number of lipid droplets (s), (Magnification X3.750.)

DSRCT may exhibit features of neuroectodermal differentiation has been raised by other investigatorst’.’ In comparing our electron microscopic findings with those of other cases of DSRCT in the literature, we noted both similarities and differences, suggesting the possibility of a range of ultrastructural features in these neoplasms. The nucleoli of the tumor cells were described as inconspicuous in one report,” which is similar to OUI case no. 2, but which contrasts with our case no. 3. Junctions have been variable in the reported cases, ranging from scant and small to more prominent ones, including desmosomes. In both of our cases that were studied ultrastructurally, frequent junctions, including those of intermediate, desmosomal, and tight types, were identified. Lumens were present in the tumors in three reports,‘-” and in our case no. 3 their presence was suggested by foci of radially arranged junctional complexes, without visible spaces or microvilli. Cellular processes were described as intertwining in one case’ and as ru460

dimentary in another.’ Processes were rather well developed in our case no. 2, but were insignificant in number and size in case no. 3. Cytoplasmic filaments were a prominent feature in three reports in the literature,“4*” and were a feature of both of our cases (nos. 2 and 3). Small, dense granules of either neuroendocrine or lysosomal types were found in sparse numbers in both of our cases (nos. 2 and 3). Dense core-type granules were described in two cases in the literature.‘.? Basal lamina, present in both our cases (nos. 2 and 3). were described around islands of cells in one report.” The differential diagnosis in cases of DSRCT involving the ovary is that of a small cell malignant tumor of the ovary. We have recently discussed most aspects of this problem in detail elsewhere’ and shall review here only those that are most pertinent to the diIIerentia1 diagnosis of DSRCT. Perhaps the most common small cell malignant tumor of the ovary with an epithelial pattern of growth is the small cell carcinoma that is usually

DESMOPLASTIC

SMALL CELL TUMOR (Young et al)

FIGURE 10. Many ot the neoplastic cells have polar processes (*), and intercellular junctions (arrow) are numerous and prominent. (Magnification A 10,400.)

asscxiatt’tt i\.ith h\,~)~~ratcen~i~~. “’ l.ike the DSRCT, this females, alttioilgh it octum01- typically OCCLII‘S in young curs in the first decade in less than 15%of the cases. In that age group, DSRCT is a more tiket?; diagnosis statistically; seven of 29 patients (three of nine females) have been under 10 years of age. The microscx)pic appearance 01 these two tumors difl’ers considerably. The small cell c;.u~cinoma rarely has a prominent desmoplastic stroma. which is characteristic of the DSRCT. and when it is present in the small cell carcinoma it is more often irreptar ill distribution and diffuse and is not associated with the di.jc.rete neoplastic nesting pattern of the latter. Like many tumors involving the ovary. the DSRCT may contain degenerative spaces that result from tumor necrosis, as siren in one of our cases, hut these spaces differ f’rotlr the. follicle-like spaces lined by neoplastic

cells that are almost always present in sn~all ct~lt carciIIOIIMS. Only rare follicle-like spaces that c.ontained eosinophilic fluid and resembled the folliclrs of the small (~11 c.arcinoma were present in OIIC of OIII. cases (case no. 1 I. While a slight majoritv of small c7tt carc%lornas have shown irnmunohis~~~~t~~~~~i~~~i staining for vimentin,’ ’ none ha\,e stained for desmin to thr best of OUI knowledge. The ultrastructural features ot rhe small cell carcinoma also differ from those of’ the DSR(:T. The former does not show a nesting patlern cxmsisting of islands of tumor cells surrounded hy basal lamina, ter01‘ rleuro~:llttocrine type minat processes. microlumens, granules. Dilated rough endoptasmic rcGxlum, the most striking uttrastructurat finding of the small cell carcinoma. ” is not a feature of the DSRCI’. The microscopic features of the DSRCT are similar to (hose of 461

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HUMAN PATHOLOGY

FIGURE 11. The frequency and arrangement of the tight junctions (arrows) and the junctional complexes in this field suggest early lumen formation. (Magnification x19.200.)

some carcinomas of the lung that fall into the category of either a small cell carcinoma or poorly differentiated squamous cell carcinoma composed predominantly of small cells. Lung carcinomas may spread to the ovaries and, rarely, the ovarian involvement may be the presenting manifestation of disease.“’ We are only aware of one case, however, in which a pulmonary neoplasm, an atypical carcinoid tumor, s read to the ovary in a patient under 20 years of age. ” Clinical assessment is obviously important in excluding a pulmonary tumor, and immunohistochemical investigation should be additionally helpful, as lung carcinomas do not exhibit the 462

typical staining profile of the DSRCT. Because of its distinct nesting pattern, the DSRCT may suggest the diagnosis of a malignant carcinoid tumor or “neuroendocrine” carcinoma. Immunohistochemical staining should help distinguish between the DSRCT and these neoplasms because, with the exception of one report,” the DSRCT has been negative for chromogranin and the cytoplasmic keratin staining has been intense and uniform rather than punctate, as is often the case fox “neuroendocrine” carcinomas. A subtype of neuroendocrine carcinoma that could mimic the DSRCT is a Merkel cell tumor metastatic to the ovary. One case of

DESMOPLASTIC

SMALL CELL TUMOR (Young et al)

FIGURE 12. The neoplastic cells have uniformly oval nuclei, finely dispersed chromatin. and large nucleoli. Occasional cells have many microfilaments within the cytoplasm (*). (Magnification k4.500.)

1his type has been reported,“’ and we have seen another ~mpublished cixample. Roth, however. occurred in paas well tients over 30 years of age. This age distribution, as other clinical features, should help in the differential diabmosis. The distinctive immunohistochemical staining of the DSRCT distinguishes it from a Merkel cell tumor ;tnd other “neuroendocrine” carcinomas. Poorly differentiated carcinomas with a somewhat hasaloid apl’earance spreading from a variety of organs c.ould potentially enter into the differential diagnosis of the DSRCT. Indeed, at one point we considered the possibility that the tumor in our first case mighl represent spread frc)m ;I cloacogenic carcinoma because there was t*xtensive tumor in the region of the lower rectum. However. it subsequently became clear that this diagIlosis was ncjt tenable because of the absence of a mucosal abnormality in the lower gastrointestinal tract. Although it did not pertain in our case, brief mention of possible confusion of the DSRCT and a metastatic rhabdoid tumor is warranted, as in the experience of some investigalors”.’ the DSRCT has had cells with dense eosinophilic- cytoplasm similar to those of the rhabdoid lumor. WV are awart‘ of only one rhabdoid tumor of

the kidnev that has been documrnted to spread to the ovarv ‘-I and, as in the other problems in diagnosis that with the DSRCT, iIrlnlLuni)tlisto~hemistry 1113k arise &uld he diagnostic. Although the paranuclear filaments that may be seen on lIltI-astI-uc.turnl examination of the DSR
463

HUMAN PATHOLOGY

tures of the ncuroblastoma and the DSRC:T differ markedly. Similar differences should help distinguish the DSRCT from the rare neurohlastoma or primitive neuroectodermal tumor (PNET) that is primary in the ovary. I!’ The PNET may he difficult to distinguish from a DSRCT on the basis of ultrastructural findings depending on the threshold for diagnosing PNET. To diagnose the latter we like to see long polar processes in a tumor that has positive neural markers by immunohistochemical staining. Microtubules and dense core granules, when present, support the diagnosis of PNET. We have not seen paranuclear filaments in the cells of a PNET. The appearance of Ewing’s sarcoma differs from that of the DSRCT. and this tumor has only rarely been documented to involve the ovary. “z” Ovarian spread is seen more often in cases of alveolar rhabdoAlthough an myosarcoma, ’ but this is also uncommon. alveolar pattern has been described in the DSRCT, it is rare and probably artifactual’ and was not a feature of our cases. The distinct nesting pattern and desmoplasia of the DSRCT should also facilitate its distinction from rhabdomyosarcoma. We also considered a small cell variant of a malignant mesothelioma,” in view of the distribution of these tunlors. The presence of rare cells positive for I,eu-Ml, or both Leu-Ml and B72.3, argues against that diagnosis. Moreover, the young age of these patients would be unusual for that diagnosis. In conclusion, the DSRCT of the peritoneum must be added to the already long list of small cell tumors that may involve the ovaries, particularly in young females. Because of its characteristic nesting pattern of growth and desmoplastic stroma, this diagnosis should be considered when these features are observed in an ovarian tumor. Appropriate immunohistochemical staining should further enable one to distin@sh this tumor from the various other neoplasms with which it may be confused.

REFERENCES

Volume 23, No. 4 (April 1992)

3. Ger;dd WI., Koui J: Desmopla~tit small tell 1un101. with diWI-gent ditfutwti;ltioli. I’ediatr Path01 0: 177. I X3, 19X0 1. <)I-done~ NC;. %irkin R. Rloom ICE:: Malignant wull-c-4 epithelial tumor. of the per.itoneum c oexpressing nlesen~hyln;ll-tying intewwliatr hlamrnts. Am J Surg l’athol 13:41?-42 I, 1089 .5. (;af~ney EF. Breatnat h F: I)iverw illlmunorea~ti\,itv and tii~t;t(.hl.oIio1is ~lltr;~stt.~i(.tui.31 variability ill fatal pl-imitive childhood tumor with rhahdoid fraruws. Ar-c h Pa&l Lab Med 113: 1322. ICI80 (Irt1er) 6. (;oriz;ll~~-(:russi I;, (Zra~fol-d SE, Sun (:J: Int~~al)donlitral drsmoplastit small-c-rll tumors with divergent differentiation. Ohservations on tIIrrr C;LW~01 childhood. Am J Surg Pathol I4:WLli_lL?,

1!NO 7. Varirnd roes todermal tO~XithOh~~

S. <~~~~rar-tlhl. Nouis I’D. et al: Intr;l-;~l)dotiiinal tumor of childhood with divergent diff’erentiation.

18:-1.‘,-51,

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(;cr-;dtl WI.. Millrr Hli, Rattifora H, ct al: IIltr;~-;~hdoInin;~l desmoplastic- smxll r~ouncl-cell tumor. Keport of I9 GLSC‘S 0f.a clistinctive type of high-grade polyphenotypic malignancy affecting ycmng indivlduals. Am ,J Surg I’athol 1.5:199-5 IS. 199 1 0. b’ic-k MR. Sw;~nsonI’E: Soft tissur tumor-s. in (:olvin KU, Hllatr RK, McCluskey RT (rds): Diagnostic Inllrlurlopatllolo~. New York. NY. Raven, 1WX, p 37 I IO. IXckersin (;K. Kline IW. Scully K6: Small c-cll car-cinema of thr ovary with Il)prl.c-al~rrlli;l: A reprxt of eleven cases. <:ance~~ 19: I xx- I97, 1982 I 1. Aguirre P. Thol- ;\I). Scully KE: Ovarian slnall cell ~;t~-cinom~~: Histogrnetic cc)trGdrraticuls Ixwd on imrnunohistocherllical and other findings. Am J Clin Pathol 92: I-10-1 49. 1089 12. McMahon JT, Hal-t U’R: Llltrastructurzd analysis of small cVII carcinomas of the &v;w Am J Clin I’athol 90:5?3-529. 198X 1Y. Young RH. Scully KE: Ov;u-ian metastases from c anwr 01 the hmg: Problems in irltri-f”‘t”tion. A report of seven cases. (+cw~l Oncol 9 1 :3:37-:V3~.IO85 14. Young RH. Kozakewit h HI%‘, Scully KE: Metastatic- ovari;m tumors in children: A report of. 14 caws aid review of. the litwaturr. Int J Gynrc-ol Path01 (in press) IS. (;corge Tli, Sant’hgncsc PA. Ketlnett JM: <:hctlrothrt.af,) for mctastatic Merhrl ccl1 c,ircinoma. Cariwt- 56: 1031-1038, I !I85 16. Himelstein-Braw K. Pctcl-s H, Faber M: Influcrlcc of irra diction and chemother-;q,y on the ovariu of children with ahdomin;al ~IIIIIOI~S. Kr ,J (Lmcer 3ti:%‘.l-27.5, 1977 17. bIe?rr U’H, YIIGW. Milvemm ES. et al: Ovarian invoIvc.mc‘nt in neurohlastotrla. MetI Pediatr Oncol 7:49-54, 1979 18. Sty JR, Km1 I.E. (&per JT: Hone srintigraphy in neurohlastonu \bith ovxian metastasis. We Med J 79:28-29. 1W.l I!). Aguirl-e 1’. Scull) RE: Malignant 1ICLIroectodel-nl;ll tumor of the ovary: A distinc tivc fi)r.m of monodermal teratoma. Keport of five caws. Am J Surg l’athol 6:2X3-202, 1982 20. Y’oung RH. Scully RE:: Sarcomas metastatir to the ocary: A repot-t of 21 cases. Int J (;ynecol Pathol 9:231-2.52, 1990 ?I. M((:aughey W’TE. ICannel-stein M. Churg J: Tumor-s and pseudotumor~ of thr SCIWS memhratres. in Atlas of Tumor F’atholou, Second Series, Fasciclc 20. \V;uhington. DC, Armed Forces Institute of I’atholo~~, 1085, 1’ -It-) X.