Giant-cell rich osteosarcoma: A report of 3 cases depicting a diagnostic challenge requiring serious attention

Abstract

Giant cell-rich osteosarcoma (GCRO) is a rare variant of osteosarcoma with unusual radiological and histopathological features that make its diagnosis challenging. The most critical and unusual feature of GCRO is that it has a purely osteolytic appearance. Therefore, GCRO cases are frequently subject to delayed diagnosis or incorrect treatment owing to misdiagnosis. This negatively affects the prognosis of these patients. In this study, 3 young adult cases are presented. The first case describes a young female patient who underwent repeated curettages due to a misdiagnosis of a giant-cell bone tumor, and the second case describes a delay in diagnosis in a young male patient who was misdiagnosed with an aneurysmal bone cyst. The final case report describes a young woman who was diagnosed early, treated promptly, and had a good prognosis. One of the poor prognosis cases in this report was treated with amputation, and the other was alive with multiple metastases. Misdiagnosis or delayed diagnosis leads to a poor prognosis in such cases. To make a diagnosis, it is necessary to have knowledge and to be suspicious of the radiological features of this rare variant. Giant cell-rich osteosarcoma should be among the differential diagnosis options when dealing with pure metaphysiodiaphyseal osteolytic bone lesions in young adults. To avoid misdiagnosis or delay, it is necessary to have knowledge and to be suspicious of this rare variant. Level of Evidence: Level IV, Therapeutic study.

Figure 1.

Radiographs (A and B), sagittal CT scan (C), and T1 weighted FatSat MR images with contrast enhancement (D-F) at the presentation. An osteolytic-cystic bone lesion with cortical destruction at the right proximal tibia containing granular opacities compatible with bone cement secondary to previous surgery. Arrow indicates intramedullary tumor with strong contrast uptake, extending through cortical destruction area to the paraosseous structures and subcutaneous plane.

Figure 2.

Local recurrence 3 years after proximal tibia resection. Coronal PET–CT scan showing increased FDG uptake in close relation with the prosthesis (A). Arrows indicating the tumor surrounding the prosthesis in MRI scans (B and C). Dashed circles showing irregular calcific soft tissue lesions around the prosthesis in specimen radiographs (D and E). The patient was treated with an above-knee amputation (F).

Figure 3.

Radiographs (A and B), contrast-enhanced coronal T1 weighted FatSat (C), T1 and T2 weighted FatSat (D) MR images at the presentation. The tumor is spreading out to the popliteal fossa through an osteolytic lesion at the medial metaphyseal cortex of the right femur. The patient presented with multiple visceral metastases 8 months after the distal femur resection (E).

Figure 4.

Radiograph showing an osteolytic lesion with an ill-defined border at the right femoral neck (A). PET–CT scan showing increased FDG uptake at the right femoral neck (B). MRI scans demonstrating an intramedullary mass showing hypointense signals in T1-weighted and hyperintense signals in T2-weighted images (C and D). The patient underwent a right proximal femoral resection with a diagnosis of low-grade spindle cell malignant mesenchymal tumor (E and F).

Figure 5.

Giant cell rich areas of the tumor without evidence of malignancy (HE ×200) (A). Malignant tumor areas with spindling of the mesenchymal cells harboring prominent atypical nuclei and high number of mitotic figures (green arrows) (HE ×400) (B). Malignant tumor areas with spindling of the mesenchymal cells harboring prominent atypical nuclei and high number of mitotic figures (black arrows) (HE ×400) (C).