A Rare Case of Primary osteosarcoma of urinary bladder
A 36-year-old male presented with a 2-month history of intermittent hematuria, dysuria, and flank pain. He had undergone cystolithotomy 20 years earlier for the treatment of bladder calculi. He also had a history of recurrent urinary tract infection and intermittent hematuria. Double J stenting was performed on the right side in a previous cystoscopy examination. Cystoscopy in our institution revealed growth in the urinary bladder, which was biopsied and the sample sent for histopathology evaluation.\nA plain radiograph of the kidney and urinary bladder showed faint specks of calcification in the region of the bladder on the left side with Double J stent on the right side []. Ultrasound showed irregular polypoidal bladder growth with multiple foci of calcification involving the vesicoureteric junctions (VUJ) on both sides. Bilateral hydrouretronephrosis was severe on the right side and moderate on the left side [].\nContrast-enhanced computed tomography (CT) scan of the abdomen and pelvis revealed a heterogenously enhancing polypoidal mass involving the lateral walls and base of the urinary bladder (including VUJ). The mass measured approximately 70 mm (anteroposterior) ×80 mm (transverse) and showed multiple specks of calcification. Loss of fat planes was noted between the urinary bladder, prostate, and seminal vesicles [Figures and ]. Bilateral hydrouretronephrosis was noted with Double J stent in situ on the right side. CT of the chest showed multiple well-defined enhancing pulmonary nodules of varying sizes (5-15 mm), with calcification being noted in some of them [].\nMicroscopic examination revealed a tumor infiltrating into the vascularized fibrocollagenous tissue with extensive tumor necrosis. Tumor cells showed marked pleomorphism, with hyperchromatic tumor cells arranged singly and in small nests. Focally, tumor cells were seen embedded in lakes of osteoid matrix with focal calcification. Diagnosis of sarcomatoid variant (osteosarcomatous type) of urothelial carcinoma was made and the sample was sent for immunohistochemistry to rule out primary osteosarcoma of the urinary bladder []. Immunohistochemical investigations showed diffusely positive results with vimentin and negative results with cytokeratin. The final pathological diagnosis made was primary extraskeletal osteosarcoma of the urinary bladder. Radiographs of the upper and lower limbs were taken to rule out skeletal osteosarcoma.