Soft tissue tumors of the urinary bladder, Part I: myofibroblastic proliferations, benign neoplasms, and tumors of uncertain malignant potential

Inflammatory pseudotumours of the urinary bladder in dogs resembling human myofibroblastic tumours: a report of eight cases and comparative pathology

Eight cases of inflammatory myofibroblastic tumours (IMT) of the urinary bladder in dogs are described, including their clinical, imaging, morphological, and histopathological aspects. Old small breed female dogs were more commonly affected. Haematuria was the main clinical sign, often associated with dysuria and crystalluria. The IMT appeared as single or multiple, polypoid, firm masses, measuring 1-7 cm. Histologically, the masses were well delineated, covered by a benign hyperplastic urothelium and diffusely infiltrated by a mixed inflammatory component. The cells were spindle-shaped, adopting a fascicular, pallisading or whirling organisation and were vimentin and variably desmin and actin positive. The nuclei were globular, containing open chromatin and prominent nucleoli. Mild to moderate pleomorphism and little mitotic activity were present. These morphological features are compatible with human myofibroblastic inflammatory tumours.

Laparoscopic enucleation of a bladder leiomyoma

Bladder leiomyomas account for less than 0.43% of all bladder tumors, and these comprise about 35% of mesenchymal tumors [1,2]. About 250 cases of bladder leiomyoma have been reported in the English literature to date [3]. A patient may or may not have symptoms, according to the location and size of the leiomyoma. Initial symptoms include urinary frequency, urgency, hematuria, and pelvic pain [4]. Treatment for bladder leiomyoma includes abdominal, vaginal, laparoscopic, or transurethral resection. Herein, we present the first case, to our knowledge, of bladder leiomyoma that was laparoscopically enucleated without cystotomy.

TP53 mutational analysis supports monoclonal origin of biphasic sarcomatoid urothelial carcinoma (carcinosarcoma) of the urinary bladder

Sarcomatoid urothelial carcinoma of the urinary bladder is an uncommon neoplasm with biphasic morphology exhibiting both epithelial and sarcomatoid components. Whether this tumor arises from a single cancer stem cell with subsequent differentiation or represents collision of the progeny of two separate cancer stem cells is a matter of controversy. To clarify its clonal origin, we analyzed the TP53 mutation status of a series of 17 sarcomatoid urothelial carcinomas using single-strand conformation polymorphism, DNA sequencing and p53 immunohistochemistry. Sarcomatoid and epithelial tumor components were separately microdissected using laser capture microdissection. Five out of the 17 sarcomatoid urothelial carcinomas contained TP53 point mutations in exons 5 and 8. In all five cases, the TP53 point mutations were identical in both the epithelial and sarcomatoid components. The sarcomatoid and epithelial tumor components in all 17 cases showed concordant p53 expression patterns. Our results suggest that despite their conspicuous divergence at the phenotypic level, the sarcomatoid and carcinomatoid elements of this uncommon tumor share a common clonal origin.

Evaluation and management of a patient with a bladder mass of uncertain etiology

BACKGROUND

A healthy, parous, nonsmoking, 36-year-old woman consulted her gynecologist for nonspecific bladder pain. Urinary tract infection was ruled out. Vaginal ultrasonography and MRI revealed an undefined tumor between the bladder and the uterus. The patient refused further testing until tumor growth was detected at a scheduled appointment 5 months after presentation. She was referred to a urology department at this time.

INVESTIGATIONS

Physical examination, urine culture, medical history, cystoscopy, MRI, angiography, intraoperative frozen section analysis, and final histology.

DIAGNOSIS

Inflammatory myofibroblastic tumor of the bladder. Management Partial cystectomy with complete excision of the tumor from the trigonal and posterior wall of the bladder by median laparotomy.

Inflammatory myofibroblastic tumors of the genitourinary tract--single entity or continuum?

PURPOSE

Inflammatory myofibroblastic tumor of the genitourinary tract is a spindled soft tissue lesion that is often mistaken for sarcoma. These tumors have been described in numerous sites in the body and have been assigned many names. The relationship between inflammatory myofibroblastic tumor and other morphologically similar entities has been a long-standing source of controversy. We investigated whether inflammatory myofibroblastic tumors in adults and children are the same entity, and whether inflammatory myofibroblastic tumor is part of a biological spectrum that includes benign and malignant entities at opposite ends.

MATERIALS AND METHODS

We performed an extensive review of the literature.

RESULTS

The literature suggests that with evidence of anaplastic lymphoma kinase rearrangement and expression, the lesion is neoplastic rather than reactive, differentiating it from previously described lesions.

CONCLUSIONS

Inflammatory myofibroblastic tumor of the genitourinary tract should be considered a neoplasm of uncertain malignant potential, and routine surveillance and close clinical followup are recommended. Aggressive therapy (radical cystectomy, radiation or chemotherapy) is unwarranted given the indolent and often benign clinical course for the majority of cases. To understand the diagnostic and prognostic implications future emphasis should be placed on the link between genetic abnormalities, and clinical course, therapeutic response and ultimate outcome.

A series of vascular tumors and tumorlike lesions of the bladder

Vascular tumors of the bladder are rare and a subject of small series and case reports. We retrospectively identified vascular tumors of the urinary bladder from the consultation files from one of the authors. We identified 13 lesions that included 3 hemangiomas, 3 intravascular papillary endothelial hyperplasias (Masson vegetant hemangioendotheliomas), 2 arteriovenous malformations (AVMs), 1 epithelioid hemangioendothelioma (EHE), and 4 angiosarcomas. One of the angiosarcomas was associated with conventional high-grade urothelial carcinoma (sarcomatoid carcinoma). All patients were adults with a range in age from 18 to 85 years old (mean 63.3). There was no statistical difference among the various lesions in terms of age, although angiosarcomas tended to arise in older patients (mean 71 y vs. 60 y of the remainder). Hematuria was the most common presentation of both benign and malignant lesions. Other symptoms included voiding irritation, pelvic pain, and obstruction. Histologically, benign and malignant lesions were similar to their counterparts in other organ systems. Two hemangiomas were of the capillary type and a third one of the cavernous subtype. They measured 1.1, 2.4, and 3.2 cm. Both AVMs were clinically large broad-based masses measuring 5.5 and 5.8 cm in greatest diameter. One of the AVMs was associated with pseudoepitheliomatous hyperplasia of the urothelium. All 3 patients with Masson lesion had history of radiation therapy for other causes. These presented as raised lesions and were all <1.0 cm. Patients with hemangiomas, papillary endothelial hyperplasias, and AVM had an invariably benign prognosis and needed no further therapy. These benign lesions had consistent involvement of the submucosa and spared the muscularis propria of the organ. All cases of angiosarcoma and EHE involved the muscularis propria. Two of four patients with angiosarcoma had a history of prior radiation therapy and all 4 were dead of disease at 6 months. Angiosarcomas measured 3, 4.5, 5, and 5.8 cm in greatest diameter at cystoscopy. The patient with EHE had a single nodule treated by transurethral resection of the bladder and no evidence of disease at 4 years of follow-up. None of the patients experienced marked gross hematuria that resulted in morbidity or mortality. A wide spectrum of benign, intermediate malignant, and malignant vascular lesions primarily involved the bladder. Despite the potential for marked hemorrhage, none of the tumors resulted in marked hematuria. Papillary endothelial hyperplasia occurs in the bladder and must be differentiated from angiosarcoma, which has a rapidly fatal outcome.

Pseudosarcomatous myofibroblastic lesion of the urinary bladder: a rare entity posing a diagnostic challenge and therapeutic dilemma

BACKGROUND

Pseudosarcomatous myofibroblastic lesions of the urinary bladder are relatively rare entities of an uncertain pathogenesis and benign indolent nature.

CASE PRESENTATION

We present an extremely rare case of an ALK-1-positive pseudosarcomatous myofibroblastic lesion of the urinary bladder, which was initially misinterpreted as a low-grade leiomyosarcoma of myxoid subtype on histologic examination owing to prominent atypia, high mitotic activity, abnormal mitotic figures and infiltration of the bladder wall. Although the histologic features were suggestive of a sarcoma, the correct diagnosis was finally established and radical surgical treatment was subsequently avoided. The patient is currently free of disease without any evidence of tumor recurrence or metastasis at 3 years post-operatively.

CONCLUSION

The key differentiating point rests in distinguishing the aforementioned mass forming lesion from the myxoid subtype of low-grade leiomyosarcoma in order to avoid unnecessary radical therapy.

Soft tissue tumors of the urinary bladder Part II: malignant neoplasms

Most bladder tumors arise from the urothelium. However, there are several uncommon but significant malignant bladder lesions that must be differentiated from urothelial carcinomas and from benign lesions of the bladder. The second half of this two-part review will describe rare nonurothelial malignant tumors of the urinary bladder including leiomyosarcoma, rhabdomyosarcoma, angiosarcoma, malignant fibrous histiocytoma (undifferentiated sarcoma), primitive neuroectodermal tumor, malignant peripheral nerve sheath tumor, hemangiopericytoma, and alveolar soft-parts sarcoma. Common clinical presentations, morphologic characteristics, and immunohistochemical features are described to aid the practicing pathologist in the identification of these entities. Because the distinction between malignant and benign lesions has significant therapeutic and prognostic implications, key factors for differentiating them are presented.