Malignant fibrous histiocytoma of bone (MFH of bone)

Epidemiology

This rare tumour constitutes less than 2% of primary malignant bone tumours.

Histopathology

There is a mixture of (myo)fibroblastic spindle cells with pleomorphic and giant cells, as well as an inflammatory infiltrate. The spindle cells form a storiform pattern. There may be stromal collagen and a myxoid matrix.

Immunohistochemistry (with osteosarcoma and MFH of soft tissue for comparison: both MFH of bone and osteosarcoma are commonly positive for smooth muscle markers, in contrast to MFH of soft tissues, which are usually negative.)

	MFH of bone	osteosarcoma	MFH of soft tissue
SMA	9/191	5/111	3/111
Calponin	9/191	4/111	1/111
SM22a	18/191	7/111	2/111
Desmin	1/191	1/111	2/111
MyoD1	2/191	0/111	0/111
HHF35	3/191	0/111	3/111

Differential diagnosis

osteosarcoma
fibrosarcoma
leiomyosarcoma: primary leiomyosarcoma of bone is extremely rare.
dedifferentiated chondrosarcoma
malignant lymphoma

References

1Ueda, T., Araki, N., Mano, M., Myoui, A., Joyama, S., Ishiguro, S., Yamamura, H., Takahashi, K., Kudawara, I. and Yoshikawa, H. Frequent expression of smooth muscle markers in malignant fibrous histiocytoma of bone. J Clin Pathol 2002;55:853-8.

This page last revised 3.11.2002.