Comparison of the Imaging and Pathological Features of Telangiectatic Osteosarcoma and Aneurysmal Bone Cyst of Long Tubular Bones

Abstract

Background: The clinical, imaging and pathological features of telangiectatic osteosarcoma (TOS) in long bones are helpful for differentiation from aneurysmal bone cysts (ABC). Objectives: To investigate the clinical, imaging and pathological features of TOS in comparison with ABC in long bones. Patients and Methods: Seventeen patients with TOS and 17 patients with ABC in our hospital were analyzed in the clinical, imaging and pathological features for proper diagnosis. Results: For plain radiographs in 17 TOS cases, a soft tissue mass was detected in 14 cases, lytic bone destruction in 13, ill-defined border in 12, periosteal reaction in eight, formation of the Codman triangle in five, pathological fracture in three, and calcification in one. In 17 cases with ABC, an ill-defined border was found in fifteen cases, lytic and expansile destruction in eleven, thinned sclerotic rim in twelve, eccentrically location in ten, coarse septations in eight, a soft tissue mass in three, pathological fracture in three, periosteal reaction in two, and ill-defined border in two cases. In CT imaging of TOS, multiple cysts were in twelve cases, and fluid-fluid levels in three. In ABC, multiple cysts were in eleven cases while fluid-fluid levels in four. In MRI presentations of TOS, low and medium signal was present in the T1-weighted imaging (T1WI), whereas mixed (9/12) or high signal (3/12) was presented in the T2 WI with inhomogeneous signal. Four cases had multiple cysts and fluid-fluid levels in the bone destruction and soft tissues. The cysts had long T1 and long T2 signal with isointense signal in the septations (5/12). Fat inhibition sequence showed clear cystic changes. In ABC, low complete or incomplete signal was demonstrated in all lesions with a higher incidence of fluid-fluid levels (8/11). The lesion was of low and medium inhomogeneous signal in the T1 WI but mixed signal in T2 WI (6/11) including hyperintense signal in the upper part but mixed signal in the lower part in four cases or hyperintense signal (1/11) in T2 WI. The histopathological features of TOS were bleeding inside the lesion, highly atypia tumor cells of malignancy in the septa and tumorous bone tissue. The septa of ABC were composed of proliferative fibroblasts with dispersed polykaryocytes, reactive woven bone but no atypical cells. Conclusion: The clinical, imaging and pathological characteristics should be combined to make a correct differential diagnosis between telangiectatic osteosarcoma and aneurysmal bone cyst.