Review Question - QID 219350

This 18-year-old male presents with a lesion on the right femur and a biopsy suspicious of telangiectatic osteosarcoma. The most appropriate treatment is neoadjuvant chemotherapy, followed by wide surgical resection and adjuvant chemotherapy.

Telangiectatic osteosarcoma (TO) represents a rare subtype of osteosarcoma most commonly seen in the long bones (proximal humerus, distal femur, proximal tibia) of those between ages 5 and 25 years. The diagnostic conundrum of the entity lies in sufficiently ruling out the possibility of aneurysmal bone cysts (ABCs), as both conditions present similarly from a clinical and diagnostic perspective. Although certain characteristics (see Illustration A) may favor one diagnosis over the other, a biopsy is a required part of the workup when considering both entities. Following histological diagnosis, the standard treatment includes neoadjuvant chemotherapy, followed by wide surgical resection with the goal of limb salvage, and adjuvant chemotherapy.

Murphey et al. performed a retrospective review of 40 individuals with histologically confirmed telangiectatic osteosarcomas in order to examine the diagnostic characteristics of the disease. The authors found many similarities between TOs and ABCs, noting expansile, cystic lesions on radiographs and hemorrhagic components on MRI as the most common characteristics, whereas the presence of cortical disruption, thick soft-tissue components, and intralesional necrosis in TOs as distinguishing factors from ABCs. They conclude histological examination is still required to obtain the diagnosis.

Zishan and colleagues similarly performed a retrospective review of all ABCs (n=152) and TOs (n=31) encountered over 11 years at a single institution. The authors found several distinguishing characteristics between the two, noting a lack of bony destruction, absence of soft tissue mass, smaller tumor size, and a larger element of fluid-fluid levels as characteristics favoring the diagnosis of ABCs. However, the authors report the standard for definitive diagnosis continues to be biopsy.

Figures 1 and 2 demonstrate orthogonal radiographs of a right femur demonstrating a mid-shaft blastic lesion with evidence of periosteal reaction. Figures 3 and 4 exhibit an expansive, cystic lesion with poorly defined fluid-fluid levels and a large soft tissue component. Illustration A is a table delineating the differences between TOs and ABCs.

Incorrect Answers:
Answer 1: Aspiration with intralesional steroid injection is a treatment commonly utilized in unicameral bone cysts, and would not be appropriate given the findings on histology in this patient.
Answer 2: Lesion curettage with possible adjuvant and grafting would be an acceptable answer had histology been suggestive of an ABC.
Answer 4: Observation with serial imaging would be appropriate, had histology suggested a benign entity.
Answer 5: Wide resection alone is not correct, as osteosarcoma can be a highly chemosensitive malignant tumor.