A case report of inflammatory myofibroblastic tumor of urinary bladder.

An old woman was admitted due to massive visible hematuria; the hematuria was difficult to control and lasted 3 days. Cystoscopy showed a solid tumor in the urinary bladder. After performing transrectal resection, histology and immunohistochemistry showed that it was inflammatory myofibroblastic tumor.

INTRODUCTION

Inflammatory myofibroblastic tumors (IMFTs) is a rare soft tissue tumor, which may occur in soft tissue and viscera such as lungs, retroperitoneum, and pelvis.[1] It has a low malignant tendency; mortality usually occur due to the tumor extension into adjacent organs. This case report presents a rare incident of IMFT found in the urinary bladder.

CASE REPORT

A 71-year-old woman was admitted to our department for massive visible hematuria lasting for 2 h; she had urgency, frequency, suprapubic pain, and dysuria. She had cystitis 2 times during the last 3 months. We started coagulation therapy (Dicynon, Kanavit, Exacyl) without effect. Three days after the admission, her hemoglobin falls to 86 g/l. Cystoscopy showed a solid tumor on the posterior wall of the bladder sized 3 cm, it looked like infiltrating tumor growing from the adjacent organs. After performing transurethral resection (TUR) of the tumor, histological report indicated that the tumor contained malignant spindle cells, partially necrotic with myxoid changes, and urinary bladder urothelium was found without dysplastic changes, it was difficult to differentiate whether it is sarcoma or sarcomatoid carcinoma. Immunohistochemistry examination was ordered, which showed later that the tumor is inflammatory myofibroblastic. Two weeks later, intravenous urography showed irregular contour on the cranial part of the urinary bladder wall. On computer tomography, there was a finger-like mass on the left lateral wall of the urinary bladder, and the fundus invading the surroundings. Two months later, we performed follow-up cystoscopy; we found a tumor on the left lateral wall of the bladder, and TUR was performed. After 3 months, no pathological findings were seen.

DISCUSSION

IMFT is a rare benign and proliferative lesion of the submucosal stroma, TUR of this tumor appears to be curative.

The first IMFT was reported by Roth in 1980,[2] since then around 100 cases of IMFT were described in English literature, four cases of IMFT in the urinary bladder were reported[3] most cases presented with gross hematuria. Histologically, the hallmark of the tumor is the presence of atypical spindle cell proliferations [Figures 1 and 2a and b].

Figure 1

Myofibroblastic cells proliferating in lamina propria, inflammatory cells are scattered in edematous stroma

Figure 2

(a and b) Inflammatory myofibroblastic tumors, the tumor is composed spindle-cells arranged in fascicles with a myxoid stroma and inflammatory cells, the cells exhibit moderate nuclear atypia. (c) Leiomyosarcoma of urinary bladder, the tumor shows diffuse immunoreactivity for caldesmon. (d) Embryonal rhabdomyosarcoma of the prostate. The nuclei of many tumor cells are immunolabeled by an antibody to myogenin

The etiology of the tumor is not clear yet,[2] but there might be an association between the tumor and chronic cystitis or previous instrumentations (e.g., cystoscopy).[3]

Other terminology for this lesion includes atypical myofibroblastic tumor, plasma cell granuloma, nodular fasciitis of the bladder, inflammatory pseudotumor, and postoperative spindle cell tumor. This lesion may occur at any age but typically occurs in young adults, the size of the lesion is variable ranging from 2 to 6 cm. According to Ricchiutti et al., only one recurrence case has been reported.

This lesion grows slowly and does not metastasize. The best treatment for this lesion is TUR and follow-up cystoscopy.[4] Previously, it was thought that this tumor is malignant; hence, unnecessary radical operations such as cystectomy were performed. Histology remains the milestone of the diagnosis; other examinations such as immunohistochemistry and electron microscopic examination can be used too. Here, we can see the importance of a correct, precise, and efficient diagnosis made by the surgical pathologist. In 10-15% of solid tumors, histochemistry, immunohistochemistry, and electron microscopy are crucial tools for making a diagnosis. The pathological report is another essential tool to enhance patients care. The report should consist of all important, available information for the pathologist, and the used technologies/tests to make the diagnosis.[5] Moreover, it was shown that using synoptic checklist yield better results and superior communication between the pathologist and the clinician than the free-text reports.[6789]

Leiomyosarcoma and rhabdomyosarcoma are the most problematic tumors in the differential diagnosis [Figure 2c and d]. Some markers can be used to differentiate between these tumors and IMFT, for example, antibodies directed against myogenin and MyoD1 (which are nuclear phosphoproteins act as transcription factors inducing gene expression in muscles), can be used as specific markers for rhabdomyosarcoma, because these antibodies do not react with cells of IMFTs.[10] In addition, it is believed that antibodies against h-caldesmon can be used as sensitive markers for leiomyosarcomas, leiomyomas, and glomus tumors.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.