Oligosarcoma, gliosarcoma arising in oligodendroglioma

Definition

An uncommon tumour of the central nervous system in which there is an admixture of oligodendroglial and sarcomatous components. The the more common equivalent combination of astrocytomatous and sarcomatous components is known as a gliosarcoma.

Epidemiology

Oligosarcomas are predominantly tumours of adults.

Macroscopic appearances

All oligosarcomas are supratentorial.

Histopathology

The oligodendroglial component comprises cells with uniformly round nuclei with perinuclear halos. In recurrences, there may be development of anaplasia. The sarcomatous component may be clearly separate or admixed; it may form septa within the glioma. The sarcoma may appear ab initio or in a recurrence. It may show features of fibrosarcoma, angiosarcoma, leiomyosarcoma or pleomorphic rhabdomyosarcoma.

Immunohistochemistry

	Oligodendroglial component	Sarcomatous component
GFAP	7/71	3/7(focal)1
S-100	7/71	negative1
SMA	0/71	6/71
CD34	0/71	4/71
EMA	0/71	2/71
AE1/AE3	0/71	0/71
Cam5.2	0/71	0/71
h-Caldesmon	0/31	0/31

Molecular genetics

The sharing of common cytogenetic abnormalities between the two components argues against a "collision" tumour.

Differential diagnosis

Post radiation sarcoma after radiotherapy for oligodendroglioma.

Prognosis

These tumours may behave aggressively.

References

1 Rodriguez FJ, Scheithauer BW, Jenkins R, et al. Gliosarcoma arising in oligodendroglial tumors ("oligosarcoma"): a clinicopathologic study. Am J Surg Pathol 2007; 31:351-62

This page last revised 9.6.2007.