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Inflammatory (pseudosarcomatous) myofibroblastic tumor of the urinary bladder causing acute abdominal pain
Inflammatory (Pseudosarcomatous) Myofibroblastic Tumor of the Urinary Bladder Causing Acute Abdominal Pain By M.P
Gardner,
A. Lowichik, Salt
Lake
and
City,
PC.
Cartwright
Utah
Inflammatory myofibroblastic tumor is a reactive proliferation of myofibroblasts that rarely involves the urinary bladder. The cause of inflammatory myofibroblastic tumor is unknown but may represent an initial reactive process to an infectious agent or trauma that transforms into neoplastic growth. Cases reported in children, however, often lack any preexisting bladder pathology. The authors present a case in a young child that presented as acute abdominal pain. In
general, these tumors follow a benign clinical course after resection, although close monitoring is essential given the rarity of this bladder lesion. J Pediatr Surg 34:1417-1419. Copyright o 1999 by W.B. Saunders Company.
I
benign transitional epithelium with an expanded submucosal and intermuscular fibromyxoid stroma with a mixed inflammatory infiltrate consisting of lymphocytes, plasma cells, neutrophils, and eosinophils. In some areas, eosinophils predominated, whereas in other regions, a lymphoid aggregate was present (Fig 2A). Near the necrotic center of the gross specimen, sheets of neutrophils were evident on microscopy, often adjacent to xanthomatous areas (Fig 2B). The proliferative stromal cells infiltrated the muscular wall of the bladder and into adjacent fibroadipose tissue but did not appear to involve the skeletal muscle of the rectus. The spindle cell proliferation assumed a “tissue culture” appearance in some areas. No malignant cellular features were identified, although a few isolated cells showed large nuclei, discemable nucleoli, and abundant cytoplasm reminiscent of ganglion cells (Fig 2C). The heterogeneous inflammatory infiltrate accompanied by the spindle cell and ganglionlike cell proliferation confirmed the diagnosis of IMT. The patient’s foley catheter was removed on postoperative day 2, and he was discharged later that day. His symptoms resolved over 4 to 6 weeks. A small, superficial wound infection developed 2 weeks after discharge, which was treated with drainage and packing. An ultrasound scan at 3 months follow-up showed a normal bladder wall.
NFLAMMATORY (pseudosarcomatous) myofibroblastic tumor (IMT) of the bladder is an uncommon cause of a bladder mass and abdominal pain in children. Although the etiology remains poorly understood, this entity uniformly follows a benign course. We report a case in a young child and discuss the significance of recognizing this condition and pursuing proper management. CASE
REPORT
A 3-year-old boy presented with a l-month history of intermittent low abdominal pain, urinary frequency, and dysmia. His symptoms worsened acutely with associated fevers to 39.l”C 24 hours before presentation. Evaluation showed lower abdominal tenderness, a white blood cell count of 16,000, and urine unremarkable for pyuria or hematuria. An abdominal ultrasound scan was interpreted as showing a possible perirectal fluid collection. He was subsequently taken to the operating room with appendicitis suspected and through an infraumbilical midline incision was found to have a 6-cm mass in the region of the bladder dome. The appendix was normal in appearance. There was no entry into the perivesical space through the peritoneum. Needle biopsies were performed, and the incision was closed. Histological evaluation results showed a dense eosinophilic infiltrate within benign smooth muscle bundles as well as occasional lymphocytic foci. The patient was then transferred to our institution. Laboratory data were notable for a white blood cell count of 3,500 with 8% eosinophils on differential and a hematocrit value of 35%. Urinalysis showed 3 to 5 red blood cells per high power tield but did not show leukocytes. Abdominal and pelvic computed tomography (CT) scan showed a large mass, with a small central hypodense area, arising within the bladder dome and extending toward the anterior abdominal wall (Fig 1). There was no obvious adenopatby. and a chest film was normal. The patient was taken to the operating room where cystoscopy showed a submucosal mass effect at the dome and anterior wall of the bladder but no disruption of mucosal continuity. The abdomen was then entered where a firm mass was palpable with extension from the dome to the anterior abdominal wall. Partial cystectomy was performed removing a 3- X 3-cm patch of detrusor and completely excising the tumor. The bladder was closed in a standard 2-layer fashion. The specimen was 4.5 X 4.7 X 3.5 cm with an area of necrosis centrally measuring 1.5 cm in diameter. Sections of the mass showed Journal
ofPecfiatric.Surgery,
Vol34,
No 9 (September),
1999: pp 1417-1419
INDEX WORDS: bladder, bladder
Inflammatory neoplasm.
myofibroblastictumor,
urinary
DISCUSSION
Inflammatory (pseudosarcomatous) myofibroblastic tumor (IMT) l is a benign reactive proliferation of myofibroblasts that may present as a bladder mass in children. It is a rare condition with less than 80 reported cases. Roth2 initially described this condition in a woman with a history of chronic cystitis. Since that time, however, various terms have been assigned to describe this condition including i@ammatoly pseudotumol;3 postoperative
From the Division of Urology University of Utah School of Medicine Centel; Salt Lake City, VT Address reprint requests to Patrick Children $ Medical Centec Pediatric Medical DI; Salt Lake City, UT84113. Copyright 0 1999 by WB. Saunders 0022-3468/99/3409-0026$03.00/O
and Department of Pathology, and Primary Children’s Medical C. Cartwright, MD, Primary Urology, Suite 2200, 100 North Company
1417
1418
Fig 1. Pelvic CT scan shows IMT as a large mass necrotic area involving the bladder dome with extension anterior abdominal wall.
GARDNER,
LOWICHIK,
AND
CARTWRIGHT
with central toward the
spindle cell nodule,4 and nodularfasciitis of the bladdex5 The term pseudosarcomatous appropriately designates this lesion as such because it is frequently mistaken for embryonal rhabdomyosarcoma, which may present with similar clinical and pathological features. Although originally believed to occur primarily in children and young adults less than 20 years of age,6 there is no age predominance. There is a slight gender predilection with more of the reported cases in patients less than 20 years of age occurring in girls (62%).1.6-9 The only exception to this was the series of 11 pediatric cases reported by Hojo et al,’ showing IMT to be nearly twice as prevalent in boys. Although the etiology remains unclear, several cases of IMT have been associated with chronic cystitis2*6,10or operative trauma to the bladder such as transurethral resection of transitional cell carcinoma in adults.4 Cases reported in most adults and particularly children, however, typically lack any preexisting bladder pathology or iatrogenic manipulation. Angulo and Lopez6 have suggested IMT may arise from abberrant proliferation of stromal cells related to embryological differentiation of the bladder. Others have examined the histological similarities of IMT and nodular fasciitis of soft tissues and speculated both conditions may represent a reactive cellular proliferation to an unknown stimulus, possibly related to cytokines or an infectious agent. ‘J Pediatric cases of inflammatory pseudotumors have been reported in other organs as well, including the lung, pancreas, mesentery, and uterus.3 The presenting features of IMT are characteristically dysuria and hematuria. Serum laboratory data are generally nonspecific, whereas urinalysis may show hematuria.6 Of note, however, lesions confined to the submucosa and bladder musculature may lack hematuria as observed in our case. Rarely, a palpable suprapubic mass may be appreciated. l2 Cystoscopically, these tumors exhibit a wide range of morphology from an ulcerating polypoid
Fig 2. Histological heterogeneity of inflammatory myoflbroblastic tumor of the bladder illustrates the importance of adequate biopsy sampling. (A) Nodules of mature lymphocytes separate relatively unremarkable smooth muscle bundles in another area. (B) Focus of neutrophils and sheets of foamy macrophages corresponding to areas of gross necrosis. (C) Loose stellate to spindle cells occasionally mimick sarcoma or ganglion cells with prominent nucleoli.
lesion to a submucosal, mural mass.l,’ In the reported cases in children, the size of the specimen is most commonly less than 5 cm and located on the bladder dome, anterior, or posterior ~all.‘,~,~ Trigone or bladder neck involvement have been reported in 2 female children8 Histologically, these lesions appear as a proliferation of myofibroblasts. Analysis of the myofibroblasts may show variable morphology based on size of nucleoli, extent of eosinophilic cytoplasmic staining, and cellular
INFLAMMATORY
MYOFIBROBLASTIC
TUMOR
1419
pleomorphism. Ganglion cell-type myofibroblasts, as seen in our patient, are appreciated less commonly than spindle-shaped cells and typically have prominent nucleoli with abundant eosinophilic cytoplasm. An acute and chronic inflammatory infiltrate, which accompanies the cellular proliferation, is also a prevalent feature of IMT. Neutrophils dominate areas of necrosis as seen in this case. Eosinophils also may be present within the cellular matrix but has been observed with less frequency than lymphocytic or macrocytic infiltrates.1*7 Of clinical importance, IMT should be considered in the differential diagnosis of any bladder mass resembling embryonal rhabdomyosarcoma. Its similar clinical and radiographic presentation to rhabdomyosarcoma unfortunately has led to radical treatment in a few cases including tumor resection followed by chemotherapy and radiation.6 The histological features that distinguish IMT from rhabdomyosarcoma is the heterogeneous appearance, lack of a cambium layer, different appearance of the spindle cell component, and decreased mitotic rate.ls7 Other causes of bladder mass that should be considered in a child, albeit with equal rarity as IMT, are leiomyosarcoma, leiomyoma, lymphoma, granulocytic sarcoma, neuroblastoma, eosinophilic cystitis, and viral cystitis.13-16Of note, the initial biopsy result in this case shows the potential for sampling error in this histologically protean lesion. The finding of a focally dense eosino-
philic infiltrate and absence of a myofibroblastic component led to consideration of an alternative diagnosis of tumor-forming eosinophilic cystitis.15 A similar diagnostic dilemma caused by prominent eosinophils within bladder specimens of IMT was described in two cases.’ Pathological diagnosis of IMT relies on multiple, deep biopsies. Thus, if a bladder mass is encountered during exploration of an acute abdomen, proceeding with biopsy seems a reasonable approach to ensure accurate diagnosis. If, however, preoperative imaging confirms the bladder as the focus of the mass, endoscopic biopsies generally are feasible while conferring less morbidity. Transurethral resection or open excision of IMT of the bladder is the mainstay of treatment.1,6-9 Currently, it is not clear whether complete excision is necessary to prevent recurrent disease. One case of recurrent IMT in an adult was presumed secondary to incomplete resection. l7 Postoperative follow-up should entail imaging at regular intervals with ultrasound scan or CT if symptoms reappear. Lesions that involved the epithelial surface of the bladder may best be managed with surveillance cystoscopy and biopsy of suspicious lesions. Long-term follow-up of the larger series may clarify the biological behavior of this disease and instill confidence in postoperative management.
REFERENCES 1. Albores-Saavedra J, Manivel C, Essenfeld H, et al: Pseudossrcomatous myofibroblastic proliferations in the urinary bladder of children. Cancer 66:1234-1241, 1990 2. Roth JA: Reactive pseudosarcomatous response in urinary bladder. Urology 16:635-637, 1980 3. Scott L, Blair G, Taylor G, et al: Inthunmatory pseudotumors in children. J Pediatr Surg 23:755-758,1988 4. Proppe KH, Scully RE, Rosai J: Postoperative spindle-cell nodules of genitourinary tract resembling sarcomas. A report of eight cases. Am J Surg Path01 8:101-108, 1984 5. Das S, Upton JD, Amar AD: Nodular fasciitis of the bladder. J Urol 140:1532-1533, 1988 6. Angulo JC, Lopez JI: myofibroblastic proliferation of the bladder: Report of 2 cases and literature review. J Urol 151:1008-1012,1994 7. Hojo H, Newton WA, Hamoudi AB, et al: Pseudosarcomatous myofibroblastic tumor of the urinary bladder in children: A study of 11 cases with a review of the literature. An intergroup rhabdomyosarcoma study. Am J Surg Path01 19:1224-1236, 1995 8. Jones EC, Clement PB, Young RH: Inflammatory pseudotumor of the urinary bladder. A clinicopathological, immunohistochemical, ultrastructural, and flow cytometric study of 13 cases. Am J Surg Path01 17:264-274, 1993 9. Stark GL, Feddersen R, Lowe BA, et al: Inflammatory pseudotumor (pseudosarcoma) of the bladder. J Urol141:610-612,1989
10. Coyne JD, Wilson G, Sanhu D, et al: Inflammatory pseudotumor of the urinary bladder. Histopathology 18:261-264,199l 11. Nochomovitz LE, Orenstein JM: Inflammatory pseudotumor of the urinary bladder-possible relationship to nodular fasciitis. Two case reports, cytologic observations, and ultrastructural observations. Am J Surg Path01 9:366-373,1985 12. Freud E, Bilik R, Yaniv I, et al: Inflammatory pseudotumor in childhood. A diagnostic and therapeutic dilemma. Arch Surg 126:653655,199l 13. Walsh PC et al (eds): Campbell’s Urology (ed 7). Philadelphia, PA, Saunders, 1998 (chap 74) 14. Cartwright PC, Faye-Petersen 0, Bybee B, et al: Leukemic relapse presenting with ureteral obstruction caused by granulocytic sarcoma. J Urol146:1354-135.5,1991 15. Gerharz EW, Grueber M, Melekos MD, et al: Tumor-forming eosinophilic cystitis in children: Case report and review of the literature. Eur Urol25:138-141, 1994 16. Londergan TA, Walzak MP: Hemorrhagic cystitis due to adenovirus infection following bone marrow transplantation. J Urol151:10131014,1994 17. Gugliada K, Nardi PM, Borenstein MS, et al: Inflammatory pseudosarcoma (pseudotumor) of the bladder. Radiology 179:66-68, 1991
Gardner,
A. Lowichik, Salt
Lake
and
City,
PC.
Cartwright
Utah
Inflammatory myofibroblastic tumor is a reactive proliferation of myofibroblasts that rarely involves the urinary bladder. The cause of inflammatory myofibroblastic tumor is unknown but may represent an initial reactive process to an infectious agent or trauma that transforms into neoplastic growth. Cases reported in children, however, often lack any preexisting bladder pathology. The authors present a case in a young child that presented as acute abdominal pain. In
general, these tumors follow a benign clinical course after resection, although close monitoring is essential given the rarity of this bladder lesion. J Pediatr Surg 34:1417-1419. Copyright o 1999 by W.B. Saunders Company.
I
benign transitional epithelium with an expanded submucosal and intermuscular fibromyxoid stroma with a mixed inflammatory infiltrate consisting of lymphocytes, plasma cells, neutrophils, and eosinophils. In some areas, eosinophils predominated, whereas in other regions, a lymphoid aggregate was present (Fig 2A). Near the necrotic center of the gross specimen, sheets of neutrophils were evident on microscopy, often adjacent to xanthomatous areas (Fig 2B). The proliferative stromal cells infiltrated the muscular wall of the bladder and into adjacent fibroadipose tissue but did not appear to involve the skeletal muscle of the rectus. The spindle cell proliferation assumed a “tissue culture” appearance in some areas. No malignant cellular features were identified, although a few isolated cells showed large nuclei, discemable nucleoli, and abundant cytoplasm reminiscent of ganglion cells (Fig 2C). The heterogeneous inflammatory infiltrate accompanied by the spindle cell and ganglionlike cell proliferation confirmed the diagnosis of IMT. The patient’s foley catheter was removed on postoperative day 2, and he was discharged later that day. His symptoms resolved over 4 to 6 weeks. A small, superficial wound infection developed 2 weeks after discharge, which was treated with drainage and packing. An ultrasound scan at 3 months follow-up showed a normal bladder wall.
NFLAMMATORY (pseudosarcomatous) myofibroblastic tumor (IMT) of the bladder is an uncommon cause of a bladder mass and abdominal pain in children. Although the etiology remains poorly understood, this entity uniformly follows a benign course. We report a case in a young child and discuss the significance of recognizing this condition and pursuing proper management. CASE
REPORT
A 3-year-old boy presented with a l-month history of intermittent low abdominal pain, urinary frequency, and dysmia. His symptoms worsened acutely with associated fevers to 39.l”C 24 hours before presentation. Evaluation showed lower abdominal tenderness, a white blood cell count of 16,000, and urine unremarkable for pyuria or hematuria. An abdominal ultrasound scan was interpreted as showing a possible perirectal fluid collection. He was subsequently taken to the operating room with appendicitis suspected and through an infraumbilical midline incision was found to have a 6-cm mass in the region of the bladder dome. The appendix was normal in appearance. There was no entry into the perivesical space through the peritoneum. Needle biopsies were performed, and the incision was closed. Histological evaluation results showed a dense eosinophilic infiltrate within benign smooth muscle bundles as well as occasional lymphocytic foci. The patient was then transferred to our institution. Laboratory data were notable for a white blood cell count of 3,500 with 8% eosinophils on differential and a hematocrit value of 35%. Urinalysis showed 3 to 5 red blood cells per high power tield but did not show leukocytes. Abdominal and pelvic computed tomography (CT) scan showed a large mass, with a small central hypodense area, arising within the bladder dome and extending toward the anterior abdominal wall (Fig 1). There was no obvious adenopatby. and a chest film was normal. The patient was taken to the operating room where cystoscopy showed a submucosal mass effect at the dome and anterior wall of the bladder but no disruption of mucosal continuity. The abdomen was then entered where a firm mass was palpable with extension from the dome to the anterior abdominal wall. Partial cystectomy was performed removing a 3- X 3-cm patch of detrusor and completely excising the tumor. The bladder was closed in a standard 2-layer fashion. The specimen was 4.5 X 4.7 X 3.5 cm with an area of necrosis centrally measuring 1.5 cm in diameter. Sections of the mass showed Journal
ofPecfiatric.Surgery,
Vol34,
No 9 (September),
1999: pp 1417-1419
INDEX WORDS: bladder, bladder
Inflammatory neoplasm.
myofibroblastictumor,
urinary
DISCUSSION
Inflammatory (pseudosarcomatous) myofibroblastic tumor (IMT) l is a benign reactive proliferation of myofibroblasts that may present as a bladder mass in children. It is a rare condition with less than 80 reported cases. Roth2 initially described this condition in a woman with a history of chronic cystitis. Since that time, however, various terms have been assigned to describe this condition including i@ammatoly pseudotumol;3 postoperative
From the Division of Urology University of Utah School of Medicine Centel; Salt Lake City, VT Address reprint requests to Patrick Children $ Medical Centec Pediatric Medical DI; Salt Lake City, UT84113. Copyright 0 1999 by WB. Saunders 0022-3468/99/3409-0026$03.00/O
and Department of Pathology, and Primary Children’s Medical C. Cartwright, MD, Primary Urology, Suite 2200, 100 North Company
1417
1418
Fig 1. Pelvic CT scan shows IMT as a large mass necrotic area involving the bladder dome with extension anterior abdominal wall.
GARDNER,
LOWICHIK,
AND
CARTWRIGHT
with central toward the
spindle cell nodule,4 and nodularfasciitis of the bladdex5 The term pseudosarcomatous appropriately designates this lesion as such because it is frequently mistaken for embryonal rhabdomyosarcoma, which may present with similar clinical and pathological features. Although originally believed to occur primarily in children and young adults less than 20 years of age,6 there is no age predominance. There is a slight gender predilection with more of the reported cases in patients less than 20 years of age occurring in girls (62%).1.6-9 The only exception to this was the series of 11 pediatric cases reported by Hojo et al,’ showing IMT to be nearly twice as prevalent in boys. Although the etiology remains unclear, several cases of IMT have been associated with chronic cystitis2*6,10or operative trauma to the bladder such as transurethral resection of transitional cell carcinoma in adults.4 Cases reported in most adults and particularly children, however, typically lack any preexisting bladder pathology or iatrogenic manipulation. Angulo and Lopez6 have suggested IMT may arise from abberrant proliferation of stromal cells related to embryological differentiation of the bladder. Others have examined the histological similarities of IMT and nodular fasciitis of soft tissues and speculated both conditions may represent a reactive cellular proliferation to an unknown stimulus, possibly related to cytokines or an infectious agent. ‘J Pediatric cases of inflammatory pseudotumors have been reported in other organs as well, including the lung, pancreas, mesentery, and uterus.3 The presenting features of IMT are characteristically dysuria and hematuria. Serum laboratory data are generally nonspecific, whereas urinalysis may show hematuria.6 Of note, however, lesions confined to the submucosa and bladder musculature may lack hematuria as observed in our case. Rarely, a palpable suprapubic mass may be appreciated. l2 Cystoscopically, these tumors exhibit a wide range of morphology from an ulcerating polypoid
Fig 2. Histological heterogeneity of inflammatory myoflbroblastic tumor of the bladder illustrates the importance of adequate biopsy sampling. (A) Nodules of mature lymphocytes separate relatively unremarkable smooth muscle bundles in another area. (B) Focus of neutrophils and sheets of foamy macrophages corresponding to areas of gross necrosis. (C) Loose stellate to spindle cells occasionally mimick sarcoma or ganglion cells with prominent nucleoli.
lesion to a submucosal, mural mass.l,’ In the reported cases in children, the size of the specimen is most commonly less than 5 cm and located on the bladder dome, anterior, or posterior ~all.‘,~,~ Trigone or bladder neck involvement have been reported in 2 female children8 Histologically, these lesions appear as a proliferation of myofibroblasts. Analysis of the myofibroblasts may show variable morphology based on size of nucleoli, extent of eosinophilic cytoplasmic staining, and cellular
INFLAMMATORY
MYOFIBROBLASTIC
TUMOR
1419
pleomorphism. Ganglion cell-type myofibroblasts, as seen in our patient, are appreciated less commonly than spindle-shaped cells and typically have prominent nucleoli with abundant eosinophilic cytoplasm. An acute and chronic inflammatory infiltrate, which accompanies the cellular proliferation, is also a prevalent feature of IMT. Neutrophils dominate areas of necrosis as seen in this case. Eosinophils also may be present within the cellular matrix but has been observed with less frequency than lymphocytic or macrocytic infiltrates.1*7 Of clinical importance, IMT should be considered in the differential diagnosis of any bladder mass resembling embryonal rhabdomyosarcoma. Its similar clinical and radiographic presentation to rhabdomyosarcoma unfortunately has led to radical treatment in a few cases including tumor resection followed by chemotherapy and radiation.6 The histological features that distinguish IMT from rhabdomyosarcoma is the heterogeneous appearance, lack of a cambium layer, different appearance of the spindle cell component, and decreased mitotic rate.ls7 Other causes of bladder mass that should be considered in a child, albeit with equal rarity as IMT, are leiomyosarcoma, leiomyoma, lymphoma, granulocytic sarcoma, neuroblastoma, eosinophilic cystitis, and viral cystitis.13-16Of note, the initial biopsy result in this case shows the potential for sampling error in this histologically protean lesion. The finding of a focally dense eosino-
philic infiltrate and absence of a myofibroblastic component led to consideration of an alternative diagnosis of tumor-forming eosinophilic cystitis.15 A similar diagnostic dilemma caused by prominent eosinophils within bladder specimens of IMT was described in two cases.’ Pathological diagnosis of IMT relies on multiple, deep biopsies. Thus, if a bladder mass is encountered during exploration of an acute abdomen, proceeding with biopsy seems a reasonable approach to ensure accurate diagnosis. If, however, preoperative imaging confirms the bladder as the focus of the mass, endoscopic biopsies generally are feasible while conferring less morbidity. Transurethral resection or open excision of IMT of the bladder is the mainstay of treatment.1,6-9 Currently, it is not clear whether complete excision is necessary to prevent recurrent disease. One case of recurrent IMT in an adult was presumed secondary to incomplete resection. l7 Postoperative follow-up should entail imaging at regular intervals with ultrasound scan or CT if symptoms reappear. Lesions that involved the epithelial surface of the bladder may best be managed with surveillance cystoscopy and biopsy of suspicious lesions. Long-term follow-up of the larger series may clarify the biological behavior of this disease and instill confidence in postoperative management.
REFERENCES 1. Albores-Saavedra J, Manivel C, Essenfeld H, et al: Pseudossrcomatous myofibroblastic proliferations in the urinary bladder of children. Cancer 66:1234-1241, 1990 2. Roth JA: Reactive pseudosarcomatous response in urinary bladder. Urology 16:635-637, 1980 3. Scott L, Blair G, Taylor G, et al: Inthunmatory pseudotumors in children. J Pediatr Surg 23:755-758,1988 4. Proppe KH, Scully RE, Rosai J: Postoperative spindle-cell nodules of genitourinary tract resembling sarcomas. A report of eight cases. Am J Surg Path01 8:101-108, 1984 5. Das S, Upton JD, Amar AD: Nodular fasciitis of the bladder. J Urol 140:1532-1533, 1988 6. Angulo JC, Lopez JI: myofibroblastic proliferation of the bladder: Report of 2 cases and literature review. J Urol 151:1008-1012,1994 7. Hojo H, Newton WA, Hamoudi AB, et al: Pseudosarcomatous myofibroblastic tumor of the urinary bladder in children: A study of 11 cases with a review of the literature. An intergroup rhabdomyosarcoma study. Am J Surg Path01 19:1224-1236, 1995 8. Jones EC, Clement PB, Young RH: Inflammatory pseudotumor of the urinary bladder. A clinicopathological, immunohistochemical, ultrastructural, and flow cytometric study of 13 cases. Am J Surg Path01 17:264-274, 1993 9. Stark GL, Feddersen R, Lowe BA, et al: Inflammatory pseudotumor (pseudosarcoma) of the bladder. J Urol141:610-612,1989
10. Coyne JD, Wilson G, Sanhu D, et al: Inflammatory pseudotumor of the urinary bladder. Histopathology 18:261-264,199l 11. Nochomovitz LE, Orenstein JM: Inflammatory pseudotumor of the urinary bladder-possible relationship to nodular fasciitis. Two case reports, cytologic observations, and ultrastructural observations. Am J Surg Path01 9:366-373,1985 12. Freud E, Bilik R, Yaniv I, et al: Inflammatory pseudotumor in childhood. A diagnostic and therapeutic dilemma. Arch Surg 126:653655,199l 13. Walsh PC et al (eds): Campbell’s Urology (ed 7). Philadelphia, PA, Saunders, 1998 (chap 74) 14. Cartwright PC, Faye-Petersen 0, Bybee B, et al: Leukemic relapse presenting with ureteral obstruction caused by granulocytic sarcoma. J Urol146:1354-135.5,1991 15. Gerharz EW, Grueber M, Melekos MD, et al: Tumor-forming eosinophilic cystitis in children: Case report and review of the literature. Eur Urol25:138-141, 1994 16. Londergan TA, Walzak MP: Hemorrhagic cystitis due to adenovirus infection following bone marrow transplantation. J Urol151:10131014,1994 17. Gugliada K, Nardi PM, Borenstein MS, et al: Inflammatory pseudosarcoma (pseudotumor) of the bladder. Radiology 179:66-68, 1991