Retroperitoneal Extraskeletal Osteosarcoma: Imaging Findings and Transarterial Chemoembolization

Ossifying metaplasia of urothelial metastases: original case with review of the literature

Background

Ossifying metaplasia is an unusual feature of urothelial carcinoma, with only a few cases reported. The largest series included 17 cases and was published in 1991. The mechanism of ossification is unknown and hypotheses of osteogenic precursor cells, inducing bone formation, are proposed.

Case presentation

A 75 year-old patient was treated for a high grade transitional cell carcinoma of the bladder by surgery, chemotherapy and radiotherapy. Histology showed foci of bone metaplasia, both at the periphery of the tumor, and in a lymph node metastasis. 1 year later, a heterotopic bone formation was discovered in the right retroperitoneal space, near the lumbar spine, increasing rapidly in size during follow-up. Several imaging exams were performed (2 CT, 1 MRI, 1 Pet-CT), but in the absence of typical features of sarcoma, diagnosis remained unclear.

Histology of a CT-guided percutaneous biopsy showed urothelial carcinoma and mature lamellar bone. Integration of these findings with the radiological description of extraosseous localization was consistent with a diagnosis of osseous metaplasia of an urothelial carcinoma metastasis. The absence of bone atypia in both the primary and metastases argues against sarcomatoid urothelial carcinoma with osteosarcomatous differentiation.

Conclusion

Osseous metaplasia of an urothelial carcinoma metastasis is unusual, and difficult to distinguish from radiotherapy induced sarcoma, or from sarcomatoid carcinoma. Rapid progression, sheathing of adjacent structures such as vessels (like inferior vena cava in our case) and nerves and bony feature of lymph node metastases necessitate histological confirmation and rapid treatment. Our case illustrates this disease and evaluates the imaging features. In addition we discuss the differential diagnosis of osseous retroperitoneal masses.

Extra skeletal osteosarcoma of gall bladder: A case report

Extraskeletal osteosarcoma is a rare malignant soft tissue tumor. At open cholecystectomy performed for gallstones, a 45-year-old woman was found to have extraskeletal osteosarcoma on histopathological examination. 1 year after surgery, the patient is symptom free and all imaging studies are normal. After multidisciplinary discussion it was decided to give no further treatment. The patient was asked to follow up three monthly. Although osteosarcoma has rarely been reported at other extraskeletal sites, this appears to be the third case of a primary tumor in the gallbladder.

Gastric wall implantation metastasis of retroperitoneal extraskeletal osteosarcoma: A case report and review of the literature

Retroperitoneal extraskeletal osteosarcoma (ESOS) is a rare and highly invasive tumor that is usually diagnosed at an advanced stage due to the insidious onset. The present study analyses a case of retroperitoneal ESOS and its clinical, radiological and therapeutic conditions, and also provides a review of the literature. A 52-year-old male was diagnosed with retroperitoneal ESOS. The patient succumbed to the condition one year after the initial surgery. During treatment, the patient underwent two additional surgeries and two courses of chemotherapy. In the present case, a peritoneal metastatic lesion of ESOS was shed from the peritoneum and implanted into the outer membrane of the stomach and metastasis was identified, this has rarely been reported in the literature. Retroperitoneal ESOS should be considered in the differential diagnosis of a retroperitoneal mass in order to facilitate the management of surgery and help determine the appropriate treatment of the disease.

SPECT/CT imaging of retroperitoneal extraskeletal osteosarcoma

The condition of a 52-year-old man was diagnosed with unresectable retroperitoneal extraskeletal osteosarcoma. SPECT/CT demonstrated a retroperitoneal extraskeletal osteosarcoma adjacent to the right upper ureter with large calcifications and increased Tc-MDP accumulation. Multiple hepatic capsular, renal fascial, and peritoneal metastases were noted. Four months later, multiple peritoneal metastases were noted at the second-look surgery. A histopathologic examination confirmed osteosarcoma.

Primary extraskeletal osteosarcoma of the seminal vesicle: a case report and literature review

A primary extraskeletal osteosarcoma (EOS) is a rare tumour. An EOS of the seminal vesicle has not been reported in the literature. We describe a case of a seminal vesicle EOS initially detected as a pre-rectal mass on a routine transrectal ultrasound in a 48-year-old man. A computed tomography (CT) scan confirmed the tumour to be arising from the left seminal vesicle. A robot-assisted laparoscopic seminal vesiculectomy was performed to avoid neurovascular bundle injury. Microscopic examination of the resected specimen showed a poorly differentiated osteosarcoma originating from the seminal vesicle. The patient received adjuvant chemotherapy. He is doing well without voiding or erectile dysfunction and he is tumour-free five months after surgery.