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Table 1 Reported cases of SOM in papillary urothelial carcinoma of the bladder

From: Stromal osseous metaplasia in urothelial carcinoma of the bladder: a rare case report and literature review

Case Age-Sex Tumor site, description ± related circumstances Histological findings IHC profile within the metaplastic component Treatment Pathologic stage and grade at the diagnosis Outcome Reference
1 60y-F Almost entire bladder: firm and irregular ulcerated mass, extremely fixated to the bladder wall with areas of calcification, 6y. after BTR and repeated cystodiathermy cauterization for bladder tumor. -WD PUC -SOM characterized by thick lamellated mature bone trabeculae, outlined by osteocytes and surrounded by osteoid material. -Other findings: squamous metaplastic changes, calcified material, no cartilage formation. WNP Partial cystectomy. pT2G3 NA [1]
2 50y-M Anterior, posterior and lateral bladder wall: multiple, nodular and partially pedunculated growths, 4y. after BTR and various occasions of cystodiathermy cauterization. -Papillary urothelial tumor with doubtful stromal invasion. -SOM characterized by osteoid and multiple slender bone trabeculae, lamellated or coarse – fibred, outlined by active osteoblasts and small osteoclasts. - Other finding: no cartilage formation. WNP Cystodiathermy cauterization after biopsy. p TxG1 Free from lesions and symptoms 5y after biopsy. [1]
3 68y-M Bladder, NOS. -WD PUC -SOM: osteoid material and bone trabeculae, NOS -Other finding: no cartilage formation. NA NA p TxG2 NA [2]; [4]
4 65y-M Right and left sides of the bladder wall: respectively large infiltrating solid tumor and papillary growth pattern. Right side solid tumor: -PD urothelial carcinoma. -SOM: osteoid formation without mineralization. -Other findings: squamous metaplastic changes; focal calcification; no cartilage formation. Left side papillary tumor: -WD PUC WNP Radiotherapy after biopsies. p T1G2 Died of pyelonephritis. [4]
5 56y-M Hard solid bladder tumor, NOS. -WD PUC -SOM: several bone trabeculae mostly calcified without visible osteoblasts. -Other findings: bone marrow- like spaces containing fat, reticulum and capillaries, without hematopoietic elements; squamous metaplastic changes, no cartilage formation WNP Left the hospital without further treatment after biopsy. p TxG2 NA [4]
6 66y-M Superior to the left ureteral orifice and posterior bladder wall: papillary stalked tumors, 18 m. after partial cystectomy and right ureteroneocystostomy for papillary urothelial carcinoma. -MD PUC -SOM: osteoid formation with fibroblasts and osteoblasts in surrounding stroma. -Other finding: no cartilage formation. WNP Total cystectomy with pelvic lymphadenectomy and ureterosigmoidostomy. p TxG2 Alive and well after surgery. [6]
7 85y-F Retrotrigonal region: solitary and pedunculated bladder tumor. -PD PUC -SOM: osteoid material and bone trabeculae, NOS. -Other finding: cartilage formation. WNP -Repeated transurethral BTR. -Total cystectomy and ileal conduit diversion. p T2b G3 NA [7]
8 84y-M Bladder neck: large exophytic tumor; 4y. after retropubic prostatectomy for prostatic hyperplasia, 5y. history of bladder urothelial carcinomas with TUBR and a 6-week course of intravesical thio-tepa. -PUC with extensive glandular differentiation. -SOM: scattered foci of osteoid, often surrounded by flattened cells resembling osteoblasts. -Other findings: focal calcification, no cartilage formation. WNP TUR. p T2 G3 Alive with disease 7 m. after last tumor resection. [2]
9 60y-M Posterior bladder wall: ill-defined sessile mass with hemorrhagic ulceration; 5 m. after TUR-prostate for benign prostate hyperplasia on which a tumor was seen and interpreted as NV-UC. -NV- UC: small nests and cords of uniform cells with occasional tubular structures. -SOM: mature and laminated bone trabeculae with benign osteocytes. WNP on metaplastic components. Radical cystoprostatectomy with adjuvant chemotherapy. p T4a Nx Mx Died of metastatic disease 11 m. after the first diagnosis. [8]
10 64y-M Lateral and posterior bladder wall: multiple nodular lesions; 26y. history of bladder amyloidosis treated by repeated TUR (6 times, last 7y. ago). -SUC with sarcomatoid differentiation and amyloidosis -SOM, NOS WNP Radical cystectomy with ileal conduit and adjuvant chemotherapy. p T3b G3 N1 M0 Alive and well. [9]
11 66y-M Posterior bladder wall: firm white – tan mass with an extensive area of ossification near the right seminal vesicle. -PUC, NOS -SOM: mature lamellated bone trabeculae outlined by osteoblasts. WNP -Radical cystoprostatectomy. -Chemotherapy (weekly taxane injection). -External beam radiotherapy. p T4b G3 NA [10]
12 3y-M Posterior bladder wall: exophytic papillomatous tumor with a thin stalk. -PUC -SOM, NOS -Other findings: glandular and squamous metaplasia. WNP on metaplastic bone. -TUR. p T1 G3 Free from lesions at 2y. follow-up. [5]
13 83y-M Right side of the bladder wall: whitish and firmer nodular growth, 13y. after RP, adjuvant radiotherapy and annual injection of leuprorelin (enantoneR) for prostatic adenocarcinoma. -WD PUC with focal component of urothelial carcinoma in situ. -SOM: multiple bone trabeculae, lamellated or coarsed-fibred with osteoid seams outlined by osteoblasts and osteoclasts. -Other finding: no cartilage formation. -CD56+ on osteoblasts. -CD68+ on osteoclasts. -Mild positivity of PS100 and P53 in osteoid areas and bone trabeculae. -MDM2-, CDK4-. -Ki 67 + 20%. TUBR with adjuvant BCG therapy. p T1 G3 -Two local recurrences over an 8-month follow-up period. -Alive and well at the time of the report. Present case
  1. IHC Immunohistochemical, NA not available, NOS not otherwise specified, WNP was not performed, SOM stromal osseous metaplasia, y years, m month, PUC papillary urothelial carcinoma, SUC solid urothelial carcinoma, NV-UC nested variant urothelial carcinoma, PD poorly differentiated, MD moderately differentiated, WD well differentiated, BTR bladder tumor resection, TUR transurethral resection, TUBR transurethral bladder resections, RP radical prostatectomy