Age / Sex : 17 / F
Chief complaint : Incidentally noted osteolytic lesion in right distal femur
What is your diagnosis?
Two weeks later, you can see the final diagonosis with a brief discussion of this case (Please submit only one answer).
Courtesy : Joon-Yong, Jung, Seoul St. Mary’s Hospital, The Catholic University of Korea
Answer: chondroblastoma with aneurysmal bone cyst change.
About 2.3cm sized well-circumscribed mass at epiphysis of right medial femoral condyle.
- Mild reactive BM edema
- No definite periosteal reaction.
- Internal fluid-fluid level.
- Probable, solid component appeared as low SI on T2 weighted image at the non-dependent portion of the mass
Giant cell tumor with aneurysmal bone cyst change.
Primary aneurysmal bone cyst
- Epidemiology : young patients (< 20 years old), male predilection
- Clinical presentation : non-specific and may include joint pain, muscle wasting, tenderness, and swelling/local mass
- Location : long bone (>75%), epiphyseal origin
- Radiographic finding : geographic lytic lesion with sclerotic margin in majority (90%), chondroid matrix (30~50%)
- MR finding
- Inhomogenously high SI mass on fluid-sensitive sequence and low SI on T1WI
- No distinct soft tissue mass
- No cortical breakthrough
- Smooth, thick periosteal reaction if present
- High signal on fluid-sensitive sequences in adjacent cortex, marrow, and soft tissue in majority of cases
- Secondary aneurysmal bone cyst can be seen
- In the majority of cases, distinguishing the primary ABC from the secondary ABC was possible based on characteristic features, including age of the patient at diagnosis and the tumor location.
- Radiology 1994; 190:467-474. Chondroblastoma: Classic and Confusing Appearance at MR Imaging.
- ONCOLOGY LETTERS 13: 2290-2296, 2017. Diagnosing and discriminating between primary and secondary aneurysmal bone cysts.