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Extraskeletal osteosarcoma arising in myositis ossificans.
E Konishi1, K Kusuzaki, H Murata
1Department of Pathology, Kyoto Prefectural University of Medicine, Japan.
Skeletal Radiology
|April 6, 2001
Summary
This case report details an extremely rare instance of extraskeletal osteosarcoma developing from myositis ossificans in a woman's wrist. The study highlights the malignant transformation of a benign soft tissue bony mass.
Area of Science:
- Orthopedic Oncology
- Soft Tissue Tumors
- Bone Pathology
Background:
- Extraskeletal osteosarcoma is a rare malignant bone tumor arising outside the periosteum.
- Myositis ossificans is a benign, non-neoplastic condition characterized by heterotopic ossification in soft tissues.
Observation:
- A 53-year-old woman presented with a 4-year history of a soft tissue bony mass on her left wrist.
- The mass initially was soft and mobile, becoming hard and fixed within the first year.
- Radiological imaging revealed features of mature myositis ossificans with "eggshell" ossification.
Findings:
- Histological examination showed a high-grade osteosarcoma between the radius and the bony shell of the myositis ossificans.
- A nonmineralized soft tissue mass was noted between the radius surface and the bony shell.
- The findings indicated malignant transformation of myositis ossificans into extraskeletal osteosarcoma.
Implications:
- This case underscores the potential for malignant transformation in long-standing myositis ossificans.
- It emphasizes the importance of thorough histopathological evaluation for soft tissue masses with ossification.
- Further research is needed to understand the mechanisms and risk factors for this rare transformation.