Desmoid Tumor of the Rectus Abdominis with Urinary Bladder Involvement: A Case Report and Review of Literature.

Desmoid tumors (DTs) account for 3% of all soft tissue tumors. They are benign and have no malignant potential with a favorable prognosis, and predominantly occur in young women. The pathogenesis and clinical behavior of DTs are still uncertain. In addition, most cases of DTs were associated with abdominal trauma (including surgery), while genitourinary involvement seemed to be quite rare. Up to now, there has been only one DT case with urinary bladder involvement reported in the literature. We, Hereby, report a 67-year-old male patient with left lower abdominal pain while micturition. Computed tomography (CT) showed a mass located at the lower aspect of the left rectus muscle with an extension attached to the urinary bladder. Based on the pathological findings of tumor specimen, a diagnosis of benign desmoid tumor (DT) of the abdominal wall was made. Laparotomy with wide local excision was carried out. The patient had a smooth postoperative recovery and was discharged after 10 days. Introduction:Historically, MacFarland first described these tumors in 1832. Etymologically, the word desmoid was first coined by Muller in 1838 and is derived from the Greek word desmos, which means band or tendon-like. Stout first used the term fibromatosis in 1961[1,2,3]. Desmoid tumors (DTs) are a kind of rare neoplasm, which represents 3% of all soft tissue tumors and 0.03% of all neoplasms with an incidence of 5 to 6 per million of the population per annum[4,5,6]. DTs predominantly affect young females with a median age of 30 to 40 years old and is more than twice in female than male patients. However, there is no gender preference in older patients [7,8]. Furthermore, the symptoms of DTs are not typical in general. Symptoms can occasionally occur due to the size and location of the tumor but usually are nonspecific. Because of its rarity and unusual behavior, DT is often associated with diagnostic and therapeutic challenges. Computed tomography (CT) and magnetic resonance imaging (MRI) is beneficial for the diagnosis of this tumor but pathological diagnosis is mandatory. Surgical resection is now considered as the most efficient treatment option for patients with DT, because it offers a good chance of long-term survival. Our case is of unusual presentation and finding of abdominal wall desmoid tumor with an extension to urinary bladder in a male patient who is 67 years old. Keywords: desmoid tumor, fibromatosis, spindle cell tumor, urinary bladder.