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Radiation-induced pseudotumor following therapy for soft tissue sarcoma
Lacey F Moore1, Mark J Kransdorf, Steven J Buskirk
1Department of Radiology, Mayo Clinic, Jacksonville, FL 32224-3899, USA.
Skeletal Radiology
|February 18, 2009
Summary
Radiation-induced pseudotumors can mimic tumor recurrence after extremity soft tissue sarcoma treatment. Magnetic resonance imaging (MRI) findings of ill-defined, enhancing masses suggest this condition, potentially avoiding unnecessary surgery.
Area of Science:
- Oncology
- Radiology
- Pathology
Background:
- Extremity soft tissue sarcomas require radiation therapy, which can cause post-treatment complications.
- Distinguishing radiation-induced changes from tumor recurrence is crucial for patient management.
Purpose of the Study:
- To determine the prevalence of radiation-induced pseudotumors after extremity soft tissue sarcoma radiation therapy.
- To describe the characteristic imaging appearance of these pseudotumors on magnetic resonance (MR) imaging.
Main Methods:
- Retrospective review of serial MR images from 24 patients treated for extremity soft tissue sarcomas.
- Analysis of 208 MR exams for focal signal abnormalities suggestive of recurrence.
- Histopathologic correlation for patients with suspected recurrence.
Main Results:
- Focal signal abnormalities were observed in 38% of patients, with 3 of these (12.5% of the total group) surgically confirmed as radiation-induced pseudotumors.
- Pseudotumors developed between 11 and 61 months post-radiation (mean 38 months) with an average dose of 5,527 cGy.
- MR imaging showed ill-defined, ovoid, intensely enhancing masses with minimal mass effect.
Conclusions:
- Radiation-induced pseudotumors are more common than previously thought in patients treated for extremity soft tissue sarcomas.
- Characteristic MR imaging findings can help differentiate pseudotumors from recurrence.
- Imaging follow-up or biopsy may be preferable to surgical re-exploration when pseudotumor is suspected.
