Abstract
Both giant synovial osteochondroma and parosteal osteosarcoma are rare musculo-skeletal tumors, often localized in the vicinity of the knee. Misdiagnosis of a malignant bone tumor can entail fatal consequences. Etiology of giant synovial osteochondroma is widely unsolved but is believed to originate from synovial chondromatosis, a mostly benign metaplasia of the synovial membrane. Parosteal osteosarcoma is a low-grade surface osteosarcoma with a propensity of local recurrence and the potential of distant metastasis and therefore requiring a different therapeutical approach. We report the case of a popliteal giant osteochondroma mimicking a parosteal osteosarcoma. Relevant facts of this rare entity regarding pathogenesis, treatment, and differential diagnoses will be discussed.
Highlights
For benign lesions of the bone, no reliable data regarding incidence rates are available
Giant synovial osteochondroma is a very rare form of an osteochondromatous tumor and not to be confused with classic osteochondroma, the most common bone tumor. Pathogenesis of this lesion is related to a synovial metaplasia in most
The critical report noted an extensive formation of osseous tissue with tiny hyalinous caps for the primary lesion. These caps showed benign cartilage with cells arranged in Discussion After clinical examination and imaging, a number of differential diagnoses for extra-osseous, heavily mineralized masses had to be taken into consideration
Summary
For benign lesions of the bone, no reliable data regarding incidence rates are available. Giant synovial osteochondroma is a very rare form of an osteochondromatous tumor and not to be confused with classic osteochondroma (osteo-cartilaginous exostosis), the most common bone tumor Pathogenesis of this lesion is related to a synovial metaplasia in most. Parosteal osteosarcoma could not be ruled out completely by standard histopathological examination, though In this case, the patient remained free of symptoms and recurrence 2.5 years after surgery. A second, smaller nodule attached to the cranial pole of the primary lesion was excised in the process Both specimens were sent for histopathologic analysis. Histopathological examination of the first surgical specimen showed a spindle-shaped 7×3.5×3.5 cm large, ossified piece of tissue (Figure 6). The critical report noted an extensive formation of osseous tissue with tiny hyalinous caps for the primary lesion These caps showed benign cartilage with cells arranged in
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call