Primary osteosarcoma of bladder diverticulum mimicking intradiverticular calculus: a case report
© Grubišić et al; licensee BioMed Central Ltd. 2011
Received: 3 March 2011
Accepted: 18 April 2011
Published: 18 April 2011
There is a well-documented relationship between urinary bladder diverticula and intradiverticular neoplasms. The great majorities of these tumors are urothelial carcinomas, but may also be of glandular or squamous type. Sarcomas occurring within bladder diverticula are exceptionally rare and highly malignant lesions, with only 20 well documented cases published in the literature to date (including carcinosarcomas). We report a case of osteosarcoma of the bladder diverticulum in a 68-year old man, which clinically mimicked intradiverticular calculus. To our knowledge, this is the second case described in the literature to date, and the first in English literature.
The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/5205089355246060.
Bladder diverticula mainly present as small, clinically insignificant anomalies. Rarely, probably due to urinary stasis and prolonged exposure to carcinogens, malignancies may arise within them. Analogous to overall distribution of bladder tumors, most intradiverticular tumors also originate from urothelial cells. Adenocarcinomas and squamous cell carcinomas are uncommon and carcinosarcomas and sarcomas are exceptionally rare within diverticula. There are only 20 well documented cases of intradiverticular sarcoma with or without carcinomatous component published in the literature to date . Eleven of them are pure sarcomas, mainly leiomyosarcomas, with isolated cases of osteosarcoma, malignant fibrous histiocytoma, fibrosarcoma and rhabdomyosarcoma. Here, we report a case of primary intradiverticular osteosarcoma which is, to our knowledge, the second case described in the literature to date, and the first in English literature .
Grossly, the bladder diverticulum exhibited tan to brown mucosa with a 3.2 × 3.5 × 1.8 cm greyish, solid tumor with gritty, firm center (Figure 1b). Microscopically, the tumor was composed of atypical, oval to spindle shaped cells with prominent mitotic activity, in some parts rimmed with lacelike osteoid (Figure 1c). In central parts of the tumor, the osteoid was mineralized and deposited as irregular trabeculae with malignant osteocytes within lacunae (Figure 1d). There were 20 slides of the tumor in bioptic material and these were thoroughly examined, but no epithelial component was found. Immunohistochemistry was performed with primary antibodies to cytokeratin (CK), cytokeratin 7 (CK 7), cytokeratin 20 (CK 20), epithelial membrane antigen (EMA), carcinoembryonic antigen (CEA), smooth muscle actin (SMA) and S-100 protein (all DAKO, Denmark). Tumor cells showed negative reaction for CK, CK 7, CK 20, EMA and CEA, which confirmed the absence of epithelial component, specifically the urothelial one. Reaction to SMA was positive, and reaction to S-100 protein was only focally positive. The diagnosis of osteosarcoma was established. The tumor invaded the whole thickness of diverticulum wall with no extension to the perivesical fat. The urothelium adjacent to the tumor showed areas of squamous metaplasia with no cytologic atypia.
Six months postoperatively the patient was alive and well. Extensive clinical examination revealed no signs of other primary tumor.
Patient died in July 2009, 2 years and 8 months after the initial symptoms had occurred. The autopsy revealed a large tumor of urinary bladder, measuring 29 × 26 × 18 cm, filling the pelvis, with extension to abdomen (Figure 2b). There were 15 slides of primary tumor in autopsy material and again, no epithelial component was identified. Metastases to lungs, heart and liver were found. There were numerous metastatic nodules in lungs, three nodules in myocardium (Figure 2c) and one nodule in liver. All nodules were histologically confirmed to be metastases of the primary osteosarcoma of the bladder diverticulum (Figure 2d).
Urinary bladder diverticula are outpouchings of bladder mucosa through weakened muscular areas of the bladder wall. They are commonly located in the posterior wall above the trigone, near the ureteral orifices and in the dome at the site of an obliterated urachus. They are mostly acquired, developing secondary due to increased intravesical pressure in patients with urethral or bladder neck obstruction and in patients with neurogenic bladder .
Cases of intradiverticular sarcomas with or without carcinomatous component reported in the literature to date
Grubišić I et al
Tsujita Y et al
Cheng CW et al
Omerglu A et al
UC + sarcoma
Bigotti G et al
SCC + sarcoma resembling MFH
Escandon AS et al
SCC + sarcoma
Garcia Figuerias R et al
SCC + sarcoma
Hara S et al
UC + SCC + leiomyosarcoma
Takei K et al
Begara Morillas F et al
Nuwahid F et al
UC + chondrosarcoma
Sarno A et al
Koizumi H et al
McCormick SR et al
Doctor VM, Karanjavala DK
Ostroff EB et al
Ostroff EB et al
Murdzhiev A, Bozhilov I
De Miguel S,
Gutierrez Sanz E
In the present case, the tumor mimicked diverticular lithiasis on radiological examination, but histologically it was composed of irregular, lacelike osteoid and closely packed anaplastic, round to spindle cells with prominent mitotic activity. More towards the center of the tumor, the osteoid was mineralized. These findings, which clearly describe the image of osteosarcoma, should be differentiated from other bone-forming tumors, like carcinosarcoma, urothelial carcinoma with osseous metaplasia and, theoretically, metastasis of osteosarcoma of other primary sites [14, 15]. The bone in the mesenchymal component of carcinosarcoma, like that in osteosarcoma, is neoplastic while that in the urothelial carcinoma with osseus metaplasia is benign-appearing. However, these can be easily distinguished from the osteocarcoma by the presence of neoplastic epithelial elements. In the present case, despite multiple sectioning, no epithelial components were found within the tumor, which was confirmed by negative immunohystochemical reactions for CK, CK 7, CK 20, EMA and CEA. The diagnosis of osteosarcoma was confirmed at autopsy.
In most cases, bladder diverticula are small and asymptomatic, but occasionally malignant transformation may occur within them. Overall incidence of sarcomas is the lowest one among urinary bladder tumors. Our case of primary intradiverticular osteosarcoma is the first such case reported in English literature. We find it very important to make a thorough investigation in patients with symptomatic diverticula because once a malignant transformation had occured, there is a predisposition for rapid spread of the tumor due to lack of muscular layer in diverticular wall.
Written informed consent was obtained from the patient's family for publication of this case report and accompanying images. A copy of the written consent is available for review by the Editor-in-Chief of this journal.
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