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RESIDENT
CASE
STUDIES
Week 1 April 21-25, 2003:
Case 3
Table of
Contents | List of Diagnoses | Case 1 |
Case
2 | Case 3
47-year-old male with right distal femur
tumor
Discussion
Leiomyosarcoma of bone is very rare, accounting for
less than 1% of all primary bone tumors. Patients range from 9 to 80 years
of age, but most patients are in their fifth or sixth decades. The most common sites are the distal femur, followed by the
proximal tibia and the proximal humerus. The tumor is presumed to arise
from the smooth muscle cells of the intraosseous blood vessels, from
fibroblasts or myofibroblasts or perivascular primitive mesenchymal cells.
The presence of prominent intraosseous vessels with malignant cells in the
perivascular area may assist in making the diagnosis (Frable WJ, verbal).
The lack of malignant osteoid argues against osteosarcoma.
Radiographic Imaging: There is a poorly defined osteolytic lesion
with a moth eaten appearance (indistinguishable from fibrosarcoma or MFH).
The cortex is frequently destroyed and periosteal reaction is seen in
about half of cases. Never
make the diagnosis of a bone tumor without radiologic information/correlation.
The microscopic appearances are similar to those of
soft tissue leiomyosarcoma and metastatic disease must be excluded. Typically there are interweaving fascicles of
spindle cells having prominent eosinophilic fibrillary cytoplasm. A non-specific storiform
pattern may be present. Mitotic figures are easily
found, as well as necrosis. Positive smooth muscle actin and desmin stain
may be useful in differentiating from fibrosarcoma and MFH. Some
leiomyosarcomas may show positive cytokeratin stain, making it difficult
to differentiate from spindle cell carcinomas. About 50% of the patients with the disease die of their
tumor. References:
- Verbal discussions - Drs. W. J. Frable and Kristen Atkins
- Weiss, S.W., Goldblum, J.R.,
Enzinger, F.M. (2001). Enzinger and
Weiss's Soft Tissue Tumors (4th ed.).
Philadelphia, PA: Mosby
Publishing.
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