Myofibroblastic proliferations of the bladder in adults are unusual lesions with a benign course. These proliferations, whether spontaneous or secondary to instrumentation, have identical morphology and behaviour. Histologically, similar lesions have been reported in the literature using different names, such as inflammatory pseudotumour, pseudosarcomatousfibromyxoidtumour, nodular fasciitis, postoperative spindle cell nodule. Recently, some authors proposed that these lesions are similar enough to be considered the same entity, designated as “pseudosarcomatousmyofibroblastic proliferation” and insisted on the necessity to distinguish them from the inflammatory myofibroblastictumour of the childhood. The latter, recently recognized as tumour, has a malignant potential and is capable of giving metastases.
We describe the case of a 68-year-old woman who presented a vesical mass. The histopathological study concluded to a pseudosarcomatousmyofibroblastic proliferation.
Pseudosarcomatousmyofibroblastic proliferation (PMP) of the bladder has been described by many. Roth  first described the lesion as a reactive pseudosarcomatous response in 1980. In the past, these lesions have often been initially misdiagnosed as malignancies such as sarcomatoid urothelial carcinoma, leiomyosarcoma, and rhabdomyosarcoma. The patient with PMP presents with symptoms that include urgency, urinary frequency, dysuria and hematuria, urinary obstruction, and pelvic pain. These tumors can occur at any age[3,4]. PMP usually appears as a polypoid or nodular, sometimes ulcerated, exophytic mass with broad attachment to the bladder wall[2,4]. Treatment usually consists of transurethral resection or partial cystectomy. PMP can grow extensively through the muscularis propria to invade the perivesicular adipose tissues, peritoneum, and omentum. Recurrence has recently been reported in 3 cases, but it has not been reported to metastasize [4,5].
A 68-year-old woman was admitted because of gross hematuria. Seven days prior to admission, she noted dark blood in her urine with dysuria. But she reported neither urgency, frequency, burning nor fever or chills. She had no history of urinary tract infection, instrumentation, trauma or other
urological problems. She was a nonsmoker and was otherwise in good health.
Physical findings on admission were essentially unremarkable.
An ultrasound study of the kidneys and the urinary bladder revealed a broad-based polypoid mass (4×3cm) which was located in the right posterolateral wall of the bladder. Cystoscopy showed a large ovoid tumor on the right lateral wall of the urinary bladder near the left ureteral orifice, Transurethral resection was performed, and pathology disclosed a picture of spindle cell proliferation in the submucosal and mucosal layers of the urinary bladder. The cellular proliferation was associated with mild nuclear atypia and eosinophilic cytoplasm within a fibrillary or myxoid background. It was compatible with pseudosarcomatousmyofibroblastic lesion of the urinary bladder.
Then, thoracic/abdominal/pelvic computed tomography was arranged and disclosed a 5×4cm mass lesion on the right posterior wall of the urinary bladder with muscle layer invasion, but no lymph node lesion and no evidence of extension or metastasis was noted. Bone scan is normal.
A radical cystectomy was done.
Histologic evaluation of the mass showed infiltration of
the bladder wall by a cellular population composed of oval,
spindled, and stellate myofibroblastic cells arranged in a loose
edematous and myxoid stroma with numerous small blood
vessels and inflammatory cell infiltrate including, lymphocytes,
plasma cells, and eosinophils. The cells were haphazardly
arranged; however, rare foci of fascicles were also noted. In the
high-power field microscopy, the tumor cells showed mild to
moderate nuclear atypia, prominent nucleoli, and eosinophilic
cytoplasm. Mitotic figures were present. However, no abnormal
figures were noted. The lesion-elicited areas of focal necrosis
associated with mucosal ulceration and invaded the muscularis
propria. In the immunohistochemical study, the tumor cells
were positive for anaplastic lymphoma kinase (ALK). A limited
population of tumor cells was immunoreactive desmine et
actine. Based on the previously mentioned morphologic
and immunohistochemical characteristics, the diagnosis of
pseudosarcomatousmyofibroblastic proliferation was finally
The post-operative course was uneventful. The patient did
not receive any adjuvant treatment. She is currently free of
disease without evidence of tumor recurrence or metastasis by
1-year follow-up (Figure 1).
PMP of the urinary bladder was first reported by Roth in
1980. He described a 32-year-old woman with recurrent
cystitis and hematuria associated with an ulcerated bladder
lesion. Unique histologic features included tumor-like, atypical
spindle cell proliferation. Histology and etiology were not defined
in Roth’s report, although chronic cystitis was characteristic in
In subsequent years, many descriptive names have been
used to describe histologically similar lesions, including
inflammatory pseudotumor, nodular fasciitis, postoperative
spindle cell nodule, pseudosarcomatousfibromyxoid tumor,
PMP, and inflammatory myofibroblastic tumor. Unfortunately,
no consensus on nomenclature seems imminent.
Recent reports show a male predominance (3:1), with a
mean patient age range at presentation of 47 to 54 years (range,
3-89 years)[4,6]. Hematuria is the most common presenting
symptom (60%). The following symptoms, pelvic pain (7%),
mass lesion (7%), obstructive symptoms (4%) and urinary tract
infection (4%) were often noted. Most cases are limited to the
bladder, although concurrent involvement of the prostate has
been reported[4,6]. Lesions range in size from 1cm to 12cm,
and are polypoid or nodular, with variable degrees of mucosal
hemorrhage and ulceration. The cut surface is graywhite to
tan-pink and often gelatinous. Microscopically, the lesions vary
from highly myxoid to highly cellular, and are composed of
bland, spindle-shaped myofibroblastic cells, with an associated
interlacing vascular network and a variable but polymorphous
inflammatory infiltrate. Mitotic rates range from 0 to 20 per
10 high-power field. Invasion into the muscularis mucosa and
muscularis propria is common, and infrequently the process
may involve perivesical adipose tissue, peritoneum or even
omentum. Necrosis, if present, is usually focal and associated
with surface ulceration or deep muscularis propria invasion.
Immunohistochemically, the spindle cells have expression
for epithelial markers such as cytokeratin AE1/3 (94%), and
smooth muscle markers such as smooth muscle actin (68%)
and desmin (60%)[4,6]. Transurethral resection or partial
cystectomy has been reported as the treatment of choice.
Whether these lesions are reactive or neoplastic is unresolved.
It has been shown recently that a t(2;5) involving the Alk-1 gene
can be demonstrated by fluorescent in situ hybridization in a
substantial number of cases with expression of Alk-1protein by
immunohistochemistry, supporting the notion that a significant
proportion of these histologically similar lesions are truly
neoplastic, while the remainder may be either reactive or harbor
a different genetic derangement .
Most lesions can be managed by transurethral resection,
although more extensive resection is sometimes required.
Cases regarded as “typical” occasionally recur locally but do
not metastasize[4,6]. Iczkowski et al.  reported the death of
1 patient who was not a candidate for definitive tumor ablation
after transurethral resection of a 13cm tumor. The tumor grew
to 37.5cm, resulting in urinary obstruction and urosepsis.
Sandhu and Iacovou7 reported the case of a patient with fullthickness
bladder invasion and tumor fixation to the rectus
sheath who was treated with 4 months of oral antibiotics. They
saw resolution of the lesion at 9 months of follow-up, and the
patient was free of recurrence after 3 years.) PMP of the
urinary bladder has unique clinical and pathologic features
that allow their distinction from primary bladder sarcoma and sarcomatoid carcinoma . The definition of PMP and
inflammatory myofibroblastic tumor of the urinary bladder
is still controversial because of the malignant potential.
Transurethral resection or partial cystectomy is sufficient to