Postgrad MedJ7 1995; 71: 692-700 i) The Fellowship of Postgraduate Medicine, 1995

Short reports

Giant retroperitoneal hemangiopericytoma

Siu-Cheung Chan, Chi-Ming Lee, Yu-Bun Ng, Chang-Huang Tsai

Department ofDiagnostic Radiology,Chang GungMemorial Hospital,222 Mai Chin Road,Keelung, Taiwan,ROCS-C ChanC-M LeeY-B NgC-H Tsai

Accepted 26 April 1995

SummaryHemangiopericytomas are rare vasculartumours that are derived from pericytes.Retroperitoneal hemangiopericytomasare usually bulky but clinically silentwhen diagnosed because oftheir slow rateof growth. A 49-year-old man, who pres-ented with only vague symptoms ofabdominal fullness for several months,was found on computed tomography tohave a huge well-defined mass with areasof low attenuation and well-enhancedsepta. The tumour was successfully re-sected and was confirmed to be a malig-nant retroperitoneal hemangiopericy-toma. It measured 30 cm in the greatestdimension. We are prompted to presentthis case as it is believed to be the largesttumour reported to date.

Keywords: hemangiopericytoma, retroperitoneal neo-plasm, computed tomography

Hemangiopericytoma is a rare vascular tumourrepresenting approximately 1% of all vascularneoplasms.' It is derived from pericytes andwas first described by Stout and Murray in1942.2 Pericytes are cells with long processesthat surround capillaries and serve to changethe calibre of the capillary lumen.3 The exactfunction ofpericytes is still unknown, but it hasbeen postulated that these cells have contractilepower.4 Hemangiopericytomas tend to be largeand well encapsulated.5 They have beenobserved in many parts of the body and in anumber of viscera but most commonly in thesoft tissue of the lower extremities.36 Approx-imately 2500, of hemangiopericytomas arisefrom the retroperitoneum and pelvic cavity.7Although the median size of the excisedtumours reported is 6.5 cm, the largest malig-nant hemangiopericytoma recorded was 23 cmin its greatest dimension.8 We are prompted toreport a giant retroperitoneal heman-giopericytoma of 30 cm in its greatest dimen-sion. To our knowledge, this is the largesttumour to date in the english literature.

Case report

A 49-year-old male presented with progressiveabdominal fullness in the past six monthswhich had become worse in the last two weeks.There were no complaints ofabdominal pain orother gastrointestinal symptoms. He had hadan anterior wall myocardial infarction six yearsearlier and was under regular cardiac care. On

physical examination, the abdomen appearedglobular in shape. It was non-tender, withdullness on percussion. Blood examination wasnegative. Small bowel series revealed peri-pherally displaced bowel loops with a centralspace-occupying lesion (figure 1). Computedtomography (CT) scan of abdomen with intra-venous contrast demonstrated a huge lobulatedretroperitoneal soft tissue mass with cystic lowattenuation zones and intervening enhancedseptations (figure 2). On exploratory laparo-tomy, a huge mass originating from the pan-creatic region with adhesion to serosa of thestomach and transverse colon was found. Thepatient underwent complete excision of thetumour mass with distal pancreatectomy andsplenectomy. He was later discharged in stablecondition. Gross pathology revealed a large,well-encapsulated tumour mass measuring30 x 20 x 15 cm and weighing 3750 g (figure3). The tumour appeared grey in colour, andwas soft with an irregular surface. On dissec-tion, there was extensive necrosis and haemorr-hage. Microscopically, the tumour showedtightly packed cells around thin-walled vas-cular channels ranging from capillary-sizedvessels to large sinusoidal spaces. The tumourcells had small round-to-oval nuclei and amoderate amount of clear cytoplasm. Spindlecells were also noted in places. The interveningvascular channels usually formed a continuousramifying vascular network or a 'staghorn'configuration. There were focal haemorrhages,necrosis and a few mitotic figures (1-2 per 10

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Figure I Small bowel series showing a space-occupying lesion with displacement of the bowel loops.

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Giant retroperitoneal hemangiopericytoma 693

Figure 2 Contrast-enhanced CT scan demonstrates alarge retroperitoneal tumour with multiple large andsmall areas of low attenuation corresponding to tumournecrosis and haemorrhage.

Figure 3 Excision demonstrated a large ret-roperitoneal hemangiopericytoma.

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Figure 4 Photomicrograph of the tumour showingvascular structures lined by a layer of endothelium andsurrounded by tumour cells with oval nuclei and amoderate amount of clear cytoplasm. A mitotic figure ispresentation (arrow) (original magnification, x 100).

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Figure S Low power view demonstrated the heman-giopericytoma with massive necrosis (originalmagnification, x 40).

high power fields). The histopathologic pictureof the tumour was compatible with malignanthemangiopericytoma (figures 4 & 5). Further-more, immnunohistochemical stains for actin,desmin, S-100, Ulex europaeus agglutinin 1were negative, while stains for vimentin werepositive.

Discussion

Hemangiopericytoma is a rare vascular neop-lasm, which is believed to arise from the cellssurrounding capillaries and postcapillary ves-sels.2 Because the growth rate of the tumour isgenerally slow, it is often large by the time it isdiagnosed, as in our case. As a result, it isusually presented with no symptoms other thanoccasional pain or abdominal fullness whichseems to be related to perineural invasion.79According to the literature, it can be foundanywhere in the body but most commonlyappears at the lower extremities (34.9%0);24.50% arises from the retroperitoneum andpelvic cavity.7 It has an equal sex distributionand occurs at between 4 and 72 years of age.4The median age at diagnosis is 45 years.7 Somecongenital cases have been reported.'0"' Thepresent patient is 49 years old, close to thequoted age and has non-specific complaints.The plain radiographic feature of most

hemangiopericytomas, is a well-demarcatedsoft tissue mass. Calcification is noted only

occasionally in the tumour (less than 1% ofcases).3,8"1''4 This non-specific finding is of nohelp in diagnosis and does not allow itsdifferentiation from other soft tissue tumours. 15Angiography may be of help in defining theanatomy and planning surgical strategy but isnot diagnostic.8 CT scanning is superior toultrasound in diagnosis of the retroperitonealtumour because of delicate cross-sectionalanatomy and abundant fat content.'6'17 Heman-giopericytoma is prominently enhanced in anintravenous contrast CT scan due to its densevascularity, particularly in the periphery of thelesion, which is helpful for the diagnosis. 18 Themass is usually well circumscribed, lobulated,large in size and has multiple areas of lowattenuation due to necrosis, haemorrhage orcystic degeneration.5" 8 All the above CTfindings are presented in our case.CT presentation of a large, lobulated, soft

tissue mass with cystic low attenuation zonesand enhancement of solid areas or septationswith or without speckled calcifications is sug-

Clinical features

* asymptomatic, but vague abdominal fullness* occasional pain due to perineural invasion,

usually a late manifestation

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694 Chan, Lee, Ng, Tsai

gestive ofbut not specific for malignant heman-giopericytoma.'9 A similar appearance on CTscan of the retroperitoneum may be seen inliposarcoma, although liposarcoma is hypovas-cular and therefore not well enhanced on intra-venous contrast CT scan and in addition, itoccasionally has CT number indicative of fat.Malignant fibrous histiocytomas may alsoappear as lobulated, inhomogenous masseswith ill-defined margins and inhomogenouscontents on intravenous contrast CT scan.Generally, of the CT images of liposarcoma,malignant fibrous histiocytoma and heman-giopericytoma, hemangiopericytoma shows thegreatest degree of contrast enhancement.Angiography can demonstrate the nature of

the tumour and its blood supply, however, CTscan plays an extremely important role indemonstrating its size and relationship to adja-cent viscera. A definite diagnosis of heman-giopericytoma is made only upon pathologicalconfirmation but the above radiological find-ings are helpful for the differential diagnosisand treatment planning.

Pathologic diagnosis of this tumour is basedon the presence of large numbers of branched,sinusoidal vascular channels surrounded byand enclosed within nests and masses ofspindle-shaped cells which can be occasionallyovoid or even round. Silver impregnations canbe used to confirm that these cells are outsidethe basement membrane of the endotheliumand hence are pericytes rather than endothelialcells. Distinguishing the tumours as benign ormalignant is based on the numbers of mitoticfigures, increased cellularity, presence of cel-lular anaplasia and foci of haemorrhage andnecrosis.7'20 McMaster et al classified thehemangiopericytoma histologically as benign,borderline malignant, and malignant on thebasis of microscopic findings such as vascularpatterns, shape of pericytes, anaplasia ofpericytes, number of mitotic figures andreticulum.4 Focal haemorrhage, necrosis andmitotic figure were found in our case whichhence was diagnosed as a malignanthemangiopericytoma. Immunohistochemicalmethods using monoclonal antibodies havebeen used recently to distinguish heman-giopericytoma and other mesenchymoma, butalso they cannot make a definite diagnosis ofthis rare tumour.2'The treatment of choice for hemangio-

pericytoma is wide surgical excision.3'8'9Because of its extreme vascularity large retro-peritoneal hemangiopericytomas have some-times been considered unresectable due to ahigh risk of inordinate blood loss. In previousreports, pre-operative vascular embolisationhas been found to be an effective adjunct to the

Treatment options

* wide surgical excision* pre-operative vascular embolisation to

minimise blood loss* postoperative radiation therapy to improve

local control rates* radiation therapy also for unresectabletumours and recurrences

* chemotherapy not proven useful

Summary points

* rare vascular tumour* clinically silent* largest tumour to date 30 cm

risky procedure.22'23 Adjuvant postoperativeradiation therapy can improve local controlrates in patients treated initially with surgery,24but complete remission of hemangiopericy-toma from radiation alone is rare.25 Forunresectable hemangiopericytomas and recur-rent problems, radiation therapy has been usedas an alternative treatment.26 Chemotherapyhas not been proven useful for the managementof resectable hemangiopericytoma7'23; only par-tial or short-term remission of metastatictumours has sporadically been reported afterchemotherapy.27Hemangiopericytomas have a uniquely vari-

able range of malignant potential. Ten-yearsurvival rate for benign lesions is approx-imately 80%, but only 29% for malignantlesions.8 Local recurrence predates metastasesin more than 50/% of reported cases.25 Due tothe location of disease, high recurrent rate andpossible metastasis, long term periodic CTscans are necessary, even after complete ex-cision of the tumour.'7

In conclusion, hemangiopericytoma shouldbe considered in the differential diagnosis of awell-defined lobular mass arising in theperitoneum or retroperitoneum, which hasmultiple large and small areas of low attenua-tion, intervening enhanced septa, with or with-out speckled calcifications in CT images. CT ishelpful in diagnosis and demonstrating thesize, location and relationship to adjacentviscera, which is important for planning treat-ment.

Thanks are due to Dr Liang-Tzu Chang, the pathologistofChang Gung Memorial Hospital, Keelung, for expertpathological opinion.

1 Ayella RJ. Hemangiopericytoma: a case report with arterio-graphic findings. Radiology 1970; 97: 611-2.

2 Stout AP, Murray MR. Hemangiopericytoma: vasculartumor featuring Zimmermann's pericytes. Ann Surg 1942;116: 26-33.

3 Binder SC, Wolfe HJ, Deterling RA. Intra-abdominalhemangiopericytoma. Arch Surg 1973; 107: 536-43.

4 McMaster MJ, Soule EH, Ivins JC. Hemangiopericytoma: aclinicopathologic study and long-term follow-up of 60patients. Cancer 1975; 36: 2232-44.

5 Goldman SM, Davidson AJ. Retroperitoneal and pelvichemangiopericytoma, clinical, radiologic and pathologiccorrelation. Radiology 1988; 168: 13-17.

6 Angervall L, Kindblom LG, Nielson JM, Stever B, Svend-sen P. Hemangiopericytoma: a clinicopathologic, angiog-raphic and microangiographic study. Cancer 1978; 42:2412-27.

7 Enzinger FM, Smith BH. Hemangiopericytoma: an analysisof 106 cases. Hum Pathol 1976; 7: 61-82.

8 Morris P, Stahl R, Liriano E, Dardik H. Giant ret-roperitoneal pelvic hemangiopericytoma. J Cardiovasc Surg1991; 32: 778-82.

9 Backwinkel KD, Diddams JA. Hemangiopericytoma: reportof a case and review of the literature. Cancer 1970; 25:896-901.

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10 Kanffman SL, Stout AP. Hemangiopericytoma in children.Cancer 1960; 13: 695-710.

11 Tulenko JF. Congenital hemangiopericytoma: case report.Plast Reconstr Surg 1968; 41: 276-7.

12 Kent KH. Hemangiopericytoma. AJR 1957; 77: 347-56.13 Mujahed Z, Vasilas A, Evans JA. Hemangiopericytoma: a

report offour cases with a review ofthe literature. AIR 1959;82: 658-66.

14 Sutton D, Pratt AE. Angiography of hemangiopericytoma.Clin Radiol 1967; 18: 324-9.

15 Yaghmai I. Angiographic manifestations of soft tissue andosseous hemangiopericytomas. Radiology 1978; 126: 653-9.

16 Stephens DH, Sheedy PF, II, Hattery RR, Williamson B, Jr.Diagnosis and evaluation of retroperitoneal tumor by com-puted tomography. AJR 1977; 129: 395-402.

17 Pinson CW, Remine SG, Fletcher WS, Braasch JW. Longterm results with primary retroperitoneal tumors. Arch Surg1989; 124: 1168-73.

18 Lorigan JG, David CL, Evans HL, Wallace S. The clinicaland radiologic manifestation of hemangiopericytoma. AJR1989; 153: 345-9.

19 Alpern MB, Thorsen MK, Kellman GM, Pojunas K,Lawson TL. CT appearance of hemangiopericytoma. JComput Assist Tomogr 1986; 10: 264-7.

20 Imachi M, Tsukamoto N, Tsukimori K, et al. Malignanthemangiopericytoma of the omentum presenting as anovarian tumor. Gynecol Oncol 1990; 39: 208-13.

21 Jimenez-Avala M, Diez-Nau MD, Larrad A, et al. Heman-giopericytoma in a male breast. Report of a case withcytologic, histologic and immunochemical studies. ActaCytol 1991; 35: 234-8.

22 Smullens SN, Scatti DJ, Osterholm JL. Preoperativeembolization of retroperitoneal hemangiopericytomas as anaid in their removal. Cancer 1982; 50: 1870-5.

23 Smith RB, Machleder HI, Rand RW, Bentson J, Tarbas P.Preoperative vascular embolization as an adjunct to success-ful resection of large retroperitoneal hemangiopericytoma. JUrol 1976; 115: 206-8.

24 Staples JJ, Robinson RA, Wen BC, Hussey DH. Heman-giopericytoma - the role of radiotherapy. Int J Radiat OncolBiol Phys 1990; 19: 445-51.

25 Craven JP, Quigley TM, Bolen JW, Raker EJ. Currentmanagement and clinical outcome of hemangiopericytomas.AmJ Surg 1992; 163: 490-3.

26 Munoz AK, Berek JS, Fu YS, Heintz PA. Pelvic heman-giopericytomas: a report of five cases and literature revew.Gynecol Oncol 1990; 36: 380-2.

27 Wong PP, Yagoda A. Chemotherapy of malignant heman-giopericytoma. Cancer 1978; 41: 1256-60.

Carcinoid syndrome due to a malignantsomatostatinoma

Omer Ozbakir, Fahrettin Kelestimur, Figen Ozturk, Erdogan Szfier, Ali Unal, Tahir EPatirolu, Kadri Guven

Erciyes UniversitySchool ofMedicine,Kayseri, TurkeyDepartment ofInternal Medicine0 OzbakirF KeletimurA tnalK GuvenDepartment ofPathologyF OzturkTE PatiroluDepartment ofSurgeryE Sozuer

Correspondence toDoq Dr FahrettinKelestimur, Erciyes1lniversitesi Tip Fakultesi IqHastaliklari Anabilim Dali,38039 Kayseri, Turkey

Accepted 26 April 1995

SummarySomatostatinoma is one of the raresttumours of the endocrine pancreas. Car-dinal manifestations of a somatosta-tinoma include gallstones, mild diabetesmellitus, steatorrhoea, diarrhoea anddyspepsia. Like any other pancreatic isletcell carcinoma, a somatostatinoma mayalso produce several different hormonessuch as adrenocorticotropic hormone,calcitonin, vasoactive intestinal polypep-tide, pancreatic polypeptide, gastrin,insulin, and glucagon. In many cases, theclinical picture is dominated by the effectof these other hormones. We present apatient with somatostatinoma in whichan immunocytochemical study of thespecimens from pancreas and livershowed a weak positive reaction for gas-trin besides a strong positive reaction forsomatostatin. Interestingly, this patientalso showed the signs of carcinoid syn-drome which was successfully treatedwith octreotide.

Keywords: somatostatinoma, carcinoid syndrome, oct-reotide

Gut endocrine tumours have a low incidence ofabout 1 in 200 000 population and 60% oftheseare carcinoids.' Somatostatinomas appear to beone of the rarest gut endocrine tumours, andthe yearly incidence is estimated to be as low as1 in 40 million people.2 In the majority of thepatients, metastatic spread is evident at thetime of presentation or shortly thereafter.

Metastatic spread is usually to the liver, withinvolvement of lymph nodes and contiguousspread also being common. It has been sug-gested that the expression of the classic triad ofsymptoms may be more common when livermetastases are present.3 Total tumour resectionis the first line of therapy in patients withpancreatic somatostatinoma, while chemo-therapy is also frequently used either as theprimary mode of therapy in disseminateddisease or as adjunctive therapy after surgery.'

Carcinoid syndrome is a clinical entity whichis usually caused by the humoral secretions ofcarcinoid tumours that originate in the midgut.Lesions other than carcinoid tumours some-times secrete serotonin and present with symp-toms of the carcinoid syndrome (see box 1). Inits most complete form, the carcinoid synd-rome involves several different organ systemssuch as the vasomotor, cardiopulmonary andgastrointestinal systems. The cardinal manifes-tations of this syndrome consist ofhepatomegaly, cutaneous flushing, facial telan-giectasia, hypotension, diarrhoea, endocardial

Carcinoid syndrome: causes

* carcinoid tumours* medullary carcinomas of the thyroid* oat-cell carcinomas of the lung* pancreatic islet cell cancers* neuroblastomas* other chromaffin tumours

Box 1

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