760 @ 1992 The Japanese Society of Pathology

A Case Report of Inflammatory Pseudosarcoma of the Urinary Bladder

Hayato Inoue', Keiichi Iwabuchil, Sadahito Kuwaol, Kiyoshi Kasail, Masayuki Furuhata2, and Toru Kameya'

A case of inflammatory pseudosarcoma of the urinary bladder in a 35-year-old Japanese male is presented. This benign lesion can easily be mistaken for spindle cell sarcoma since it consists of rhabdomyoblast-like elongated strap cells showing infiltrative growth, and whether it is benign or malignant is difficult to determine by microscopic examination. In this case, spindle cell proliferation extended among bundles of the superficial muscle layer. However, no abnormal mitoses, severe nuclear atypia or cellular pleomorphism could be seen, thus indicating inflammatory pseudosarcoma. Although the lesion was not completely resected, no recurrent disease has been clinically observed for two years following transurethral resection. Urologists and surgical pathologists must be able to detect this lesion in order to avoid unnecessary surgical procedures. Acta Pathol Jpn 42 : 760-765, 1992. Key words : Inflammatory pseudosarcoma, Urinary bladder

mixed with inflammatory mononuclear cells. No abnormal mitotic figures are present. Both urologists and surgical pathologists should be aware of this lesion in order to avoid unnecessary surgery.

CASEREPORT The patient was a 35-year-old Japanese male who presented with acute onset of asymptomatic gross hematuria on July 13, 1989. He had been healthy without any significant personal or family medical history. There was no history of pelvic trauma, surgical operations or urinary tract infection. The findings of a previous physical examination had been unremarkable. Laboratory test data were within normal limits except for gross hematuria. Urine cultures were invariably nega-

An inflammatory pseudosarcoma of the urinary bladder is a very rare benign proliferative lesion and was first described in 1980 by Roth(1). It is a unique lesion considered to be an exuberant granulation tissue proliferation accompanying chronic cystitis. It may thus be called a reactive pseudosarcomatous response in the urinary bladder. In 1985, Nochomovitz and Orenstein reported two cases to which they gave the name, inflammatory pseudotumor of the urinary bladder because the lesion resembled a malignant tumor clinically and radiologically (2). Histologically, it is composed of atypical spindle cells possessing hyperchromatic nuclei scattered in markedly myxomatous stroma and Received May 22, 1992. Accepted for publication July 29, 1992. Departments of 'Pathology and 2Urology, Kitasato University, School of Medicine, Kanagawa. Mailing address: Hayato Inoue, M.D., Department of Pathology, Kitasato University, School of Medicine, Kitasato 1-151, Sagamihara, Kanagawa 228, Japan.

Figure 1. Axial CT image shows a mass protruding from the

anterior wall of the bladder.

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Acta Pathologica Japonica 42 (10): 1992 Table 1. Antisera for lmmunohistochemistry Antiserum to Epithelia I membrane antigen S-100 protein Cytokeratin low molecular weight high molecular weight Viment in Desmin a1-antichymotrypsin Cathepsin D Factor VIII,-relative antigen a,-smooth muscle actin Myoglo bin

Abbreviation EMA s-100

Dilution x 200 x 400

Source Lipshaw, MI, USA DAKO JAPAN, Kyoto, Japan

AE-1 AE-3 VIM DES AACT CD FVllla ASMA MG

x 200 x 400 x 200 x 400 x 500 x 450 x 800 x 1,000 x 200

ICN, IL, USA ICN, IL, USA DAKO JAPAN DAKO JAPAN, Kyoto, Japan Lipshaw, MI, USA NOVOCASTRA LAB, England Behringwerke AG, Germary ICN, IL, USA Lipshaw, MI, USA

tive. A computed tomography (CT) scan indicated a tumor mass on the bladder dome (Fig. 1). Regional lymph nodes were not enlarged. On July 22, he was referred to Kitasato University Hospital. Transurethral ult rasonotomogra phy showed an irreg ula r mass (approximately 3-5 cm in size) protruding into the bladder cavity. On the following morning, the patient suddenly developed massive hematuria and clot retention. Emergency cystoscopy was performed and a localized, pedunculated lesion measuring 3 x 3 . 5 cm in size was observed in the bladder dome. The surface was smooth and there was slight bleeding. On the same day, transurethral resection of the lesion was conducted, and the tumor was diagnosed as inflammatory pseudosarcoma of the urinary bladder. During a two year follow-up period, neither hematuria nor tumor recurrence has been observed.

tion of birefringent spindle cells, most of which lay in edematous or myxomatous stroma containing mononuclear inflammatory cells and numerous capillaries (Fig. 2). The cellularity of the tumor was rather sparse. Cellular proliferation extended among bundles of the superficial muscle layer without destroying or replacing them (Fig. 3). The spindle cells had elongated, tapered and partially eosinophilic cytoplasmic processes. The nuclei were moderately hyperchromatic and some of them varied in size and shape; nucleoli were conspicuous.

MATERIALS AND METHODS The resected specimens, consisting of small 'fragile, slimy fragments, weighed 30 g were fixed in 10% formalin and processed into 3 p m paraffin-embedded sections. These were stained with hematoxylin and eosin (HE), Masson's trichrome, phosphotungstic acid hematoxylin (PTAH) and immunostained by the avidin-biotin-peroxidase (ABC) complex method (3) (Vector Lab, Burlingame, CA, USA). The antibodies used, their sources and working dilutions are summarized in Table 1. Small portions of tumor fragments were re-fixed in 2.5% glutaraldehyde, postfixed in 1% osmium tetroxide and processed for transmission electron microscopy. Ultrathin sections stained with uranyl acetate and lead citrate were studied by 100-SX electron microscope (Nippon Denshi, Tokyo, Japan).

RESULTS Microscopic examination revealed a dominant popula-

Figure 2. A dominant population of widely separated spindle cells scattered in edematous stroma with abundant capillaries. HE.

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lnflamatory Pseudosarcoma of the Urinary Bladder (Inoue et a/.)

Figure 3. Extensive growth infiltrating bundles of the superficial muscle layer. HE.

Figure 4. Spindle cells with vacuolat. ed cytoplasm. No atypical mitosis is seen. HE.

Mitotic figures were present, but no abnormal mitoses could be detected (Fig. 4). The cytoplasm of the spindle cells stained pale red with Masson's trichrome stain. Examination of the sections stained with PTAH showed no cytoplasmic cross-striations. lrnmunohistochemically, the spindle cells were strongly positive for desmin, diffusely positive for vimentin and a,-smooth muscle actin, but not with other antibodies such as epithelial membrane antigen (EMA), S-100 protein, cytokeratin (AE-1, AE-3), cathepsin D, factor Vlll-related antigen (FVIIIa), and myoglobin.

Ultrastructurally, the tumor cells were extremely elongated and sparsely arranged in loose stroma and frequently had at least one blunt end. The nuclei were oval to round, occasionally folded with a peripheral zone of heterochromatin and one or two large reticular nucleoli. In most cells, well-developed, rough endoplasmic reticulum (RER) was abundant with occasionally dilated cisternae. A prominent Golgi apparatus was also seen. The cytoplasm was characterized by numerous dilated profiles of rough endoplasmic reticulum (Fig. 5). Features characteristic of fibroblastic cells were evident.

Acta Pathologica Japonica 42 (10): 1992

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Figure 5. Nuclei of tumor cells have fine, uniform euchromatin network and the dilated rough endoplasmic reticulum is well developed in the cytoplasm. ~7,000.B a r = l pm.

Myofibroblastic differentiation with cytoplasmic microfilaments associated with dense bodies was not recognized. There was no indication of striated muscle differentiation. The fibroblastic nature of the atypical spindle cells was supported by immunohistochemicaI a na lys is, and electron microscopy. The myofibroblastic properties were shown by immunohistochemistry, but not by EM. Clinical follow-up data supported their benign nature. The final diagnosis was thus inflammatory pseudosarcoma.

DISCUSSION Inflammatory pseudosarcoma of the bladder was first reported by Roth in 1980 (1). It resembled a malignant tumor histologically, and was designated as reactive pseudosarcomatous response in the urinary bladder. Various descriptive terms, such as reactive pseudosarcomatous response (l),postoperative spindle cell nodule (4), inflammatory pseudotumor (2), pseudosarcomatous fi bromyxomato us tumor (5), and pseudosarcomatous myofibroblastic proliferations (6) have been applied to these lesions. Since then, 24cases have been reported, but none in Japan. The present case is the first report concerning a

Japanese patient. The clinical and pathologic features are summarized in Table 2. The lesions in some cases were accompanied by predisposing factors such as recurrent cystitis (1, 7) and previous surgical procedures of the urinary bladder (4, 8, 9).Regarding the postoperative spindle cell nodule, Wick et a/. considered some cases t o possibly represent the proliferation of epithelial cells mechanically entrapped in the submucosa as a result of previous surgery accompanied by stromal response (9). Most reported cases, however, indicate no previous surgical history (2, 5, 6, 10, 1l), as in this case. Asymptomatic gross hematuria is the most common initial manifestation and is sometimes significant enough to cause anemia due to bleeding from exophytic and ulcerated lesions. Laboratory studies are usually noncontributory. The lesions varied considerably in size from 1.5 to 13 cm in diameter (mean 4.0 cm) and were found at various sites of the urinary bladder. A t cystoscopy, the mass always gives the impression of malignancy. Inflammatory pseudosarcoma of the urinary bladder should be distinguished from leiomyosarcoma and rhab domyosarcoma. Clinically, the inflammatory pseudosarcoma simulates sarcoma owing to its polypoid, hemorrhagic, or myxoid appearance on endoscopic examination

764

lnflamatory Pseudosarcoma of the Urinary Bladder (Inoue ef a/.) Table 2. Age, Sex, Symptoms, Predisposing Factors and Size of Tumors of Reported Cases -

Rep0rter( s)

Age/Sex

Roth (1) Proppe et a/. (4) Nochomovitz et a/. (2) Ro et a/. (5) Young et a/. (8) Scott et a/. (7) Wick et a/. (9) Stark e t a/. (11) Albores-Saavedra et a/. (6)

Gugliada et a/. (10) Present study

-

32/F 29/M 22/M 73/F 56/F 52/F 59/M 5/? 55/M 60/M 19/M 16/F 7/F 5/F 15/F 16/F 5/M 8/F 7/M 3/F 12/F 2/F 55/F 27/M 35/M

Symptoms Hematuria FoIIOW-UPof TUR' Hernaturia Hematuria Hematuria Hematuria FoIIOW-UPof TUR Hernaturia Hernaturia FOIIOW-UPO f TUR Hematuria Hernaturia Hematuria Hematuria Hematuria Hernaturia Hernaturia Hematuria S t ra ngury Hematuria Dysuria Dysuria Suprapubic pain Hematuria Hematuria

Predisposing factor Rec urrent cvst it is TUR for TCC** None None None None TUR for TCC Recurrent cystitis After surgical procedure TUR None None None None None None None None None None None None None None None

Diameter of Tumor (cm) 1.5 ?

5 5 2 4 2 13 3 3 2 3 4 3 2 ? ?

3 5 3 ? ?

8 4.5 3.5

Transurethral resection. * * Transitional cell carcinoma.

(6, 12). Histologically, it consists of compact, haphazard fascicles of spindle cells, often with a prominent and delicate vascular pattern, focal acute and chronic inflammation and ext ravasated erythrocytes. Myxoid intercellular material is usually sparse or absent from this lesion. The spindle cells may contain numerous mitotic figures, but atypical forms are not seen, and there is little or no nuclear pleomorphism. The inflammatory pseudosarcoma may invade the urinary bladder musculature but less frequently displays the extensive infiltration seen in leiomyosarcoma (12). The present tumor had microscopic features such as low cellularity, inflammatory infiltrates in the stroma, granulation tissue-like vascularity, absence of atypical mitoses, n e crosis, and minimal infiltrative growth into the muscle layers, indicating a benign nature. Electron microscopy disclosed features such as abundant RER and prominent Golgi zones characteristic of fibroblastic cells (5). The myofibroblastic nature of the atypical spindle cells was further substantiated by immunohistochemical analysis, but not by EM. PTAH sections showed no cytoplasmic cross-striations. The fibroblastic cells were positive for vimentin in most immunohistochemically examined cases, positive for desmin and cytokeratin in some cases, and negative for EMA, S-100 protein, FVllla and myoglobin (5, 6, 8, 9, 12). Wick et a/. considered cytokeratin-positive cases t o represent entrapped epithelial

cells (9). Their benign character is supported by clinical follow-up data. Recently, a close histogenetic relationship between inflammatory pseudosarcoma (pseudotumor) and nodular fasciitis has been postulated by Nochomovitz and and Ro et a/. (5). NoOrenstein(2), Stark et a/. (ll), chomovitz and Orenstein tentatively conclude inflammatory pseudosarcoma (pseudotumor) of the bladder to possess histologic similarities to nodular fasciitis which shows an invasive tendency, frequent mitotic figures, distinct nucleoli, and rapid growth, but the growth is always self-limited. There is no report in the literature documenting local recurrence or distant metastasis following excision (2). The urinary bladder lesion would thus appear to be a special variant of nodular fasciitis. The optimal management for these lesions has not been established. Stark et a/. state that pseudosarcoma does not recur even though resection is incomplete, as in nodular fasciitis (11). Recently, however, Gugliada et a/. reported the first case of recurrence of an inflammatory pseudosarcoma of the bladder after transurethral resection (TUR) of the tumor four times during 18 months. It was resected by TUR and laser vaporization each time and showed the histology of an inflammatory pseudosarcoma (10). They thus consider that partial cystectomy may prevent recurrence, but emphasize that the initial management should be trans-

Acta Pathologica Japonica 42 (10): 1992 urethral resection, with follow-up cystoscopy and biopsy t o document resolution. In conclusion, it is important t o recognize inflammatory pseudosarcoma as benign, and there has been no report of its malignant transformation. Surgical pathologists should keep in mind the possibility of a n inflammatory pseudosarcoma t o avoid unnecessary radical operations. Acknowledgements : We are grateful to Mrs Tomoko Tsuruta, Kuniko Kadoya and Benio Sat0 of the Morphology Division at our institute for their technical assistance. The members of the Electron Microscope Laboratory Center of Kitasato University School of Medicine are gratefully acknowledged for preparing electron micrographs.

REFERENCES Roth JA. Reactive pseudosarcomatous response in urinary bladder. Urology 16: 635-637,1980. Nochomovitz LE and Orenstein JM. Inflammatory pseudotumor of the urinary bladder-possible relationship to nodular fasciitis: Two case reports, cytologic observations, and .ultrastructural observations. Am J Surg Pathol 9: 366-373,1985. Hsu SM, Raine L, and Fanger H. Use of avidin-biotinperoxidase complex (ABC) in immunoperoxidase techniques : A comparison between ABC and unlabelled antibody (PAP) procedures. J Histochem Cytochem

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29: 577-580,1981. 4. Proppe KH, Scully RE, and Rosai J. Postoperative spindle cell nodules of genitourinary tract resembling sarcomas : A report of eight cases. Am J Surg Pathol

8: 101-108,1984. 5. Ro JY, Ayala AG, Ordonez NG, Swanson DA, and Babaian RJ. Pseudosarcomatous lesions of the urinary bladder. Am J Clin Pathol 86: 583-590,1986. 6. Albores-Saavedra J, Manivel JC, Essenfeld H, ef a/. Pseudosarcomatous myofibroblastic proliferations in the urinary bladder of children. Cancer 66: 1234-

1241,1990. 7. Scott L, Blair G, Taylor G, Dimmick J, and Fraser G. Inflammatory pseudotumors in children. J Pediatr Surg 23 : 755-758,1988. 8. Young RH and Scully RE. Pseudosarcomatous lesions of the urinary bladder, prostate gland, and urethra. Arch Pathol Lab Med 111 : 354-358,1987. 9. Wick MR, Brown BA, Young RH, and Mills SE. Spindle-cell proliferations of the urinary tract: An immunohistochemical study. Am J Surg Pathol 12: 379-

389,1988. 10. Gugliada K, Nardi PM, Borenstein MS, and Torno RB. Inflammatory pseudosarcoma (pseudotumor) of the bladder. Radiology 179: 66-68,1991. 11. Stark GL, Feddersen R, Lowe BA, et a/. Inflammatory pseudotumor (pseudosarcoma) of the bladder. J Urol 141 : 610-612,1989. 12. Mills SE, Bova GS, Wick MR, and Young RH. Leiomyosarcoma of the urinary bladder: A clinicopathologic and immunohistochemical study of 15 cases. Am J Surg Pathol 13: 480-489,1989.

A case report of inflammatory pseudosarcoma of the urinary bladder.

A case of inflammatory pseudosarcoma of the urinary bladder in a 35-year-old Japanese male is presented. This benign lesion can easily be mistaken for...
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