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Injection site pseudosarcoma in piriformis syndrome.
Dan C Phan1, Briana C Gleason, Xuemo Fan
1Department of Pathology and Laboratory Medicine, Cedars-Sinai Medical Center, Los Angeles, CA 90048, USA.
Histopathology
|September 3, 2011
Summary
Reactive myofibroblastic proliferations can mimic sarcoma after injections. Awareness of this injection site reaction is crucial for accurate diagnosis in muscle resections.
Area of Science:
- Pathology
- Surgical Pathology
- Musculoskeletal Pathology
Background:
- Pseudosarcomatous reactive myofibroblastic proliferations are known post-surgical or post-traumatic reactions.
- These reactions have not been previously documented at injection sites.
Purpose of the Study:
- Evaluate the prevalence, morphologic patterns, and clinical resolution of reactive myofibroblastic proliferations at injection sites.
- Raise awareness of this diagnostic pitfall in skeletal muscle resections.
Main Methods:
- Analysis of 266 surgical resection specimens from piriformis syndrome treatment.
- Identification of three cases with exuberant intramuscular fibroblastic/myofibroblastic proliferations.
Main Results:
- Three cases exhibited reactive proliferations mimicking sarcoma.
- All three cases had preceding local injections of cortisone and bupivacaine.
- Clinical follow-up showed no evidence of uncontrolled growth.
Conclusions:
- Reactive myofibroblastic proliferations at injection sites can mimic sarcoma.
- Clinical history of injections is critical for accurate interpretation of skeletal muscle resections.
- Awareness of this entity aids in avoiding misdiagnosis of entrapment syndromes.
