Pleomorphic leiomyosarcoma
Pleomorphic leiomyosarcoma is defined as a sarcoma showing typical leiomyosarcomatous fascicles but in which more than two thirds of the tumour is of pleomorphic morphology. Pleomorphic leiomyosarcoma differs from ordinary leiomyosarcoma in its morphology, reduced immunoreactivity for muscle markers, increased proliferative activity and more aggressive behavior. Pleomorphic leiomyosarcoma accounts for about 9% of all leiomyosarcomas.
Clinical features
Pleomorphic leiomyosarcoma tends to occur in middle aged to elderly adults, particularly in the extremities and retroperitoneum.
Histopathology
In most (23 of 281) cases, the pleomorphic areas blend with the leiomyosarcomatous fascicular areas.
Immunohistochemistry (with ordinary leiomyosarcomas and MFH for comparison):
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pleomorphic leiomyosarcoma
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ordinary leiomyosarcoma
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storiform-pleomorphic MFH
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fascicular areas
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pleomorphic areas
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desmin
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18/281
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10/281, 3/62
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15/201
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3/161
focally positive(less than 5% of the tumour cells)
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muscle actin (HHF-35)
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26/281
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13/281, 2/62
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14/201
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1/161
focally positive(less than 5% of the tumour cells)
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SMA
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24/281
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14/281
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15/201
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1/161
focally positive(less than 5% of the tumour cells)
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calponin
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20/281
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16/281
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18/201
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2/161
focally positive(less than 5% of the tumour cells)
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h-caldesmon
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11/281
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5/281
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11/201
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0/161
focally positive(less than 5% of the tumour cells)
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Myo-D1
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0/5(these five cases showed rhabdoid features)1
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0/5(these five cases showed rhabdoid features)1
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myogenin
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0/5(these five cases showed rhabdoid features)1
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0/5(these five cases showed rhabdoid features)1
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p53 staining more than 10% of nuclei
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8/281
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5/201
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5/161
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murine double-minute 2
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15/281
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8/201
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6/161
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average MIB-1 labelling index
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26.11
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26.21
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12.91
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16.61
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Cases with prominent osteoclast-like giant cells were excluded from this study1.
Differential diagnosis
Among sarcomas, prominent pleomorphism is seen in pleomorphic sarcoma NOS (storiform-pleomorphic MFH), pleomorphic liposarcoma and pleomorphic rhabdomyosarcoma.
Prognosis
Of 22 with a significant period of follow up, 15 died of disease1.
References
1 Oda, Y., Miyajima, K., Kawaguchi, K.et al. Pleomorphic leiomyosarcoma: clinicopathologic and immunohistochemical study with special emphasis on its distinction from ordinary leiomyosarcoma and malignant fibrous histiocytoma. Am J Surg Pathol 2001; 25:1030-1038.
2 Hashimoto, H., Daimaru, Y., Tsuneyoshi, M., Enjoji, M. Soft tissue sarcoma with additional anaplastic components. A clinicopathologic and immunohistochemical study of 27 cases. Cancer 1990;66:1578-1589.
This page last revised 26.12.2001.