Solitary fibrous tumour of the prostate

Solitary fibrous tumour has been reported in a range of extrapulmonary sites, including the prostate.

Clinical features

This tumour presents in middle aged to elderly adults. The tumour may be intraprostatic or may arise outside the prostate between bladder and rectum.

Histopathology

The tumour is composed of short spindle cells. Nuclei have dispersed chromatin and inconspicuous nucleoli. There is alternation of cellular and hypocellular myxoid zones. Variable amounts of densely wire-like hyalinised collagen are present.

Immunohistochemistry

	CD34	12/131
	bcl-2	11/11(focal in one case)1
	CD99	7/10(weak in 2 cases)1
	b-catenin	5/101
	CD117	0/101
	p53	0 to 50% of cells
	Ki-67	0 to 30% of cells

Differential diagnosis

Sarcomatoid carcinoma: shows cytological atypia, mitotic activity and is positive for cytokeratins.
GIST: positive for CD117.
Smooth muscle tumours: positive for myogenic markers , negative for CD34 and bcl-2.
Schwannoma: positive for S-100.
Stromal tumour of uncertain malignant potential (STUMP): positive for CD34.

References

1 Herawi M,Epstein JI. Solitary fibrous tumor on needle biopsy and transurethral resection of the prostate: a clinicopathologic study of 13 cases. Am J Surg Pathol 2007; 31:870-6

This page last revised 2.7.2007.