Pediatric Surgery International

, Volume 23, Issue 8, pp 815–819

Inflammatory myofibroblastic tumor of the bladder in children: what can be expected?

Authors

    • Department of Surgery, Prince of Wales HospitalThe Chinese University of Hong Kong
  • A. Chan
    • Department of Anatomical and Cellular Pathology, Prince of Wales HospitalThe Chinese University of Hong Kong
  • K. H. Lee
    • Department of Surgery, Prince of Wales HospitalThe Chinese University of Hong Kong
  • Y. H. Tam
    • Department of Surgery, Prince of Wales HospitalThe Chinese University of Hong Kong
  • K. F. To
    • Department of Anatomical and Cellular Pathology, Prince of Wales HospitalThe Chinese University of Hong Kong
  • W. Cheng
    • Department of Surgery, Prince of Wales HospitalThe Chinese University of Hong Kong
  • C. K. Yeung
    • Department of Surgery, Prince of Wales HospitalThe Chinese University of Hong Kong
Case Report

DOI: 10.1007/s00383-007-1885-y

Cite this article as:
Houben, C.H., Chan, A., Lee, K.H. et al. Pediatr Surg Int (2007) 23: 815. doi:10.1007/s00383-007-1885-y

Abstract

Inflammatory myofibroblastic tumor of the bladder is an uncommon condition of unknown neoplastic potential. In adults the tumor is seen in association with instrumentation of the lower genitourinary tract, while in children it appears to run an idiopathic course. Its clinical and radiological presentation in children resembles sarcoma. The case of a 10-year-old girl with inflammatory myofibroblastic tumor is presented, outlining the histological and immunhistochemical features to allow differentiation between sarcomas, the most important differential diagnosis. An outcome meta-analysis of the literature identified 35 cases of inflammatory myofibroblastic tumor in the bladder of children. Conservative surgery is the strategy of choice. There is no evidence of recurrence or metastasis at a median follow up of 1.5 years.

Keywords

Inflammatory myofibroblastic tumorSarcomaBladder tumorMeta-analysis

Introduction

Inflammatory myofibroblastic tumors (IMTs) are neoplastic proliferations with an inflammatory infiltrate composed primarily of lymphocytes and plasma cells. The lesions with a low to intermediate neoplastic potential were initially described in the lungs [1]. They have since been recognized in most organ systems including the central nervous system [2].

We report the case of a teenager with an IMT of the bladder and perform a meta-analysis of the literature on bladder IMTs in children up to the age of 16 years to assess the outcome. Individual cases were incorporated into the study if sufficient demographics and surgical data were available for assessment [214].

Case report

A 10-year-old girl was presented with a one-month history of dysuria and frequency accompanied by a feeling of incomplete voiding. Several urine analyses including a urine culture were all negative.

Subsequently she attended the A&E department with a tender suprapubic mass, the upper margin just 5 cm below the umbilicus. An ultrasound scan showed a heterogeneous polypoid soft tissue mass arising from the superior and anterior wall of the bladder. The patient was referred to our institution for further management of a suspected rhabdomyosarcoma.

Magnetic resonance imaging of the abdomen and pelvis showed an irregular and lobulated tumor mass measuring 45 × 55 mm centered at the antero-superior aspect of the urinary bladder (Fig. 1). A diagnostic work up which included a CT scan of the thorax and abdomen, a bone scan and a bone marrow aspirate were negative.
https://static-content.springer.com/image/art%3A10.1007%2Fs00383-007-1885-y/MediaObjects/383_2007_1885_Fig1_HTML.jpg
Fig. 1

MRI of the lower abdomen and pelvis. a Transverse view T2 weighted image, b sagittal view T1 weighted image, arrows indicate the tumor

The oncology team opted for an ultrasound guided biopsy of the suprapubic mass in preference to a cystoscopic biopsy. The histology showed spindle cell proliferation in a fascicular pattern with a mixed inflammatory cell infiltrate consistent with IMT.

Cystoscopic evaluation confirmed the tumor at the antero-superior aspect of the bladder wall. The tumor together with a small margin of normal looking bladder was excised via a pfannenstiel incision.The histology of the specimen confirmed the biopsy result: fascicles of spindle cells among fibrous and fibro-myxoid stroma with a mild mixed inflammatory infiltrate (Fig. 2a). The tumor infiltrated along the muscular wall with involvement of peri-vesicular soft tissue and submucosa; the resection margins were clear.
https://static-content.springer.com/image/art%3A10.1007%2Fs00383-007-1885-y/MediaObjects/383_2007_1885_Fig2_HTML.jpg
Fig. 2

Inflammatory myofibroblastic tumor of the bladder. a Fascicles of spindle cells among fibrous and fibro-myxoid stroma with mild mixed inflammatory infiltrate. b The tumor cells are highlighted by imunostaining of ALK-1 in cytoplasmic pattern. c The tumor cells are negative for myogenin. d The proliferative pool assessed by MIB1/Ki67 is estimated to be around 5%. (Original magnifications × 400)

A distinct cytoplasmic granular positivity could be seen for anaplastic lymphoma kinase 1 (ALK-1) (Fig. 2b). The proliferative pool as assessed by MIB1 stain (antibody against Ki 67) was estimated as approximately 5% (Fig. 2d). Together with the negative myogenin result, a rhabdomyosarcoma could be excluded (Fig. 2c). Further immunohistochemistry showed the spindle cells stained positive for smooth muscle actin (SMA), desmin and calponin. Other markers (e.g., CD34 and c-kit/CD117) were negative.

The post-operative recovery was uneventful and her initial urinary symptoms disappeared shortly after discharge. She was well at 6 months follow-up. Ultrasound scan showed an unremarkable echo texture of the bladder. Regular review, initially every 3 months, is planned.

Discussion

IMT is an uncommon tumor believed to be a reactive or reparative process, which results in cell proliferation resembling a tumorous growth. The word pseudotumor is frequently included in the various terminologies used to describe the unique features of this lesion [5, 15, 16]. In children and young adults IMTs are most often encountered intra-abdominally in the mesentry and omentum [15, 17]. The subgroup of IMTs of the bladder mimic clinically and radiologically a sarcoma making the differentiation particularly difficult.

In addition to our patient the literature review identified 34 cases of IMT of the bladder in children with sufficient data available for comparative analysis (Table 1) [214]. Of these 35 patients (20 girls) the median age of presentation was 7 (range 2–16) years. The most common presentation was hematuria in 26 patients (74%). The tumor is rarely palpable [4].
Table 1

Review of previously reported cases of children with IMT in the bladder

Author

n

Age

Presentation

Location within bladder

Therapy

FU

Scott 1988

1

5 years/F

Recurrent UTI

NS

TC

NS

NED

Stark 1989

1

10 years/F

Hematuria

Base

PC

17 months

NED

Albores-Saavedra 1990

10

median 7 years (range 2–16) 8 F, 2 M

Hematuria 7

Dysuria 2

Mass 1

NS 6

Base 2

Dome 1

Neck 1

LE 6

PC 2

TC 2

Median 2 years range (1.5–6)

NED

Freud 1991

1

2 years/M

Dysuria

Ant wall

PC

1.5 years

NED

Lamovec 1992

1

2 years/F

Dysuria

Base

TC

8 months

NED

Angulo 1994

1

16 years/M

Hematuria

Dome

PC

10 years

NED

Hojo 1995

10

median 7 years (range 3–15) 6 M, 4 F

Hematuria 10

NS 4

Dome 3

Ant wall 1

Post wall 2

LE 2

PC 8

Median 1 year range (2 weeks to 3.5 years)

NED

Foschini 1995

2

2 years/M

4 years/M

Hematuria

Hematuria

NS

NS

LE

LE

7 years

8 years

DUC

NED

Lakshmanan 1997

1

4 years/M

Hematuria

Post wall

PC

4 months

NED

Gardener 1999

1

3 years/M

Abdo pain

Dome

PC

3 months

NED

Meyer 2000

1

3 years/F

Hematuria

Dome

PC

9 months

NED

Choi 2000

1

7 years/F

Dysuria

Base

PC

1 year

NED

Mergan 2005

3

7 years/F 15 years/M 6 years/F

Hematuria

Hematuria

Hematuria

NS

NS

NS

PC

PC

PC

2 years

5 years

2 months

NED

NED

NED

Houben 2007

1

10 years/F

Mass

Dome

PC

6 months

NED

LE local excision, PC partial cystectomy, TC total cystectomy, NS not specified, NED no evidence of disease, DUC died of unrelated cause

Information regarding the location of the tumor within the bladder was available in just over half the patients and was most often found at the dome of the bladder (eight cases).

The most common operative management was a partial cystectomy in 21 patients (60%) followed by local excision in ten cases (29%). In four cases a cystectomy was performed. This was due to pre-operative diagnosis of sarcoma in three patients and because conservative surgery was deemed impossible in one patient [2, 4, 6].

Follow up data was not available in five patients. One patient died of an unrelated cause, 7 years after surgery and had a normal bladder with no evidence of metastasis at post-mortem [9]. The remaining 29 patients had a median follow-up of 1.5 years (range 2 weeks to 10 years) and there has been no evidence of recurrence or metastatic disease.

The etiology of IMTs remains unclear. In his series of 13 adult patients, Jones postulated an association with previous bladder instrumentation in three of these patients [16]. Others have implicated recurrent urinary tract infections (UTIs) as the preceding factor [8]. However the UTI may have been the result of the developing bladder lesion.

In the available literature on bladder IMTs in children, only one case was identified to have a possible causative factor. A 2.5-year-old boy was found to have a stitch granuloma, secondary to a left sided inguinal herniotomy in infancy [5]. This granuloma was found in close proximity to his bladder IMT.

It is difficult to distinguish between clinical features, radiological findings and even cystoscopic appearances of a sarcomatous proliferation and an IMT (Fig. 1).

Therefore, careful biopsy of the lesion is mandatory to avoid unnecessary radical surgery as seen in three of the cases. The IMTs were mistaken for spindle cell sarcoma, rhabdomyosarcoma and leiomyosarcoma respectively [2, 4].

Immunohistochemical markers were evaluated for their potential to identify specific lesions. Anaplastic lymphoma kinase (ALK) has been suggested as a good marker for IMT. Freeman reports eight out of nine bladder IMTs stained positive for cytoplasmic ALK, as it did in our case (Fig. 2b) [18]. This result is not shared by other investigators who report less than 20% positivity for ALK in young patients [14, 19]. The non-specific expression of ALK gene product has been further highlighted by its identification in sarcomas [20].

Myogenin, a potent marker for rhabdomyosarcoma, helped in our immunohistochemical work up by exclusion of this tumour (Fig. 2c) [21].

The meta-analysis of currently available data favors a conservative surgical approach either by partial cystectomy or local excision as the surgical strategy of choice [5, 22]. Transurethral resection has been reported for bladder IMTs, but this intervention in children is frequently followed by conversion or partial cystectomy at a later stage [8, 13].

There is currently no evidence of recurrence or metastasis for bladder IMTs in children. However a close follow up of the patients appears to be prudent for three reasons: firstly, the duration of follow up in the available literature is rather short and we are not certain about the long-term prognosis. Secondly, a positive ALK marker in some patients, as in our case, implies a neoplastic potential [14, 23] and thirdly, recurrences have been reported in cases of pulmonary and abdominal IMTs [17, 24].

Copyright information

© Springer-Verlag 2007