Abstract
Metastatic renal osteosarcoma is a rare entity. We report a case of a 52-year-old male postright nephrectomy status presented to us with metastatic renal osteosarcoma. 18-fluorine- fluorodeoxyglucose (18F-FDG) avid lesions were seen in the right renal bed with extension to adjacent hepatic parenchyma. The patient exhibited a favorable response to 6 cycles of carboplatin and doxorubicin with no FDG avid lesions in the postchemotherapy follow-up scan. On 6-month follow-up scan, scan findings reveal a recurrent lesion at the renal bed region infiltrating psoas muscle and liver metastatic lesion. This case highlights the use of 18F-FDG positron emission tomography/computed tomography in metastatic recurrent extraskeletal osteosarcoma.
Keywords: Extraosseous, fluorodeoxyglucose positron emission tomography/computed tomography, osteosarcoma, recurrence, renal
Informed consent
Informed consent from the patient was obtained to be included in the study.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient has given his consent for his images and other clinical information to be reported in the journal. The patient understands that his name and initials will not be published and due efforts will be made to conceal identity, but anonymity cannot be guaranteed.
Conflicts of interest
There are no conflicts of interest.
Figure 1.
A 52-year-old male with biopsy-proven case of extraskeletal (renal) osteosarcoma had right nephrectomy for that presented with clinical suspicion of recurrence, referred for positron emission tomography/computed tomography (PET-CT). Axial CT (a) images show soft tissue lesion in the renal bed region. Fused PET-CT transaxial (b) and coronal (c) sections depict hypermetabolic nodular lesions at the right renal bed infiltrating (c, blue arrow) adjacent liver parenchyma (c, black arrow) with SUV max 8.0. The patient underwent six cycles of carboplatin and doxorubicin following which posttherapy fluorodeoxyglucose (FDG) PET-CT scan was repeated, which showed complete metabolic resolution of all the previously noted lesions in the axial CT (d), axial PET-CT (e), and coronal PET-CT (f) sections. Follow-up FDG PET-CT scan done after 6 months to assess disease status, demonstrated hypermetabolic ill-defined heterogeneously enhancing soft tissue lesion in the operated right renal bed (h, white arrow; i, black dashed arrow) with SUV max 10.9, infiltrating into the adjacent hepatic parenchyma-segment VI (i, white dashed arrow) and right psoas muscle (i, blue dashed arrow) suggestive of recurrent metastatic disease. Extraskeletal osteosarcoma is a rare malignant bone-forming tumor originating in the soft tissues without skeletal attachment.[1] Some of the extraosseous sites that are reported in the literature are kidneys,[2] gallbladder,[3] lower extremities,[4] retroperitoneum,[5] and colon.[6] Renal osteosarcoma has been reported as an aggressive disease.[7] FDG avidity of the metastases in extraosseous osteosarcoma is similar to primary lesion and extension to nearby structures can be noted and has been reported by few studies earlier.[8] This case highlights the role of FDG PET-CT in diagnosis, treatment response evaluation, and detection of recurrence in metastatic extraskeletal (renal) osteosarcoma
Figure 2.
Tumor histopathology sections showing (low power) tumor infiltrating the normal renal parenchyma (a) with high power showing tumor cells with oval-to-elongated nuclei exhibiting moderate-to-marked nuclear pleomorphism, abundant eosinophilic cytoplasm with deposition of pericellular osteoid (b). Immunohistochemistry of tumor cells (c, blue arrow) shows diffuse immunoreactivity for SATB2 (c)
Funding Statement
Nil.
References
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