Locally advanced solitary fibrous tumour of the prostate

Abstract

Solitary fibrous tumours (SFTs) are rare mesenchymal neoplasms composed of spindle cells, most often occurring in the pleura. SFTs arising from the prostate are exceptionally rare, with only around 40 cases reported in literature to date. We report a man in his 60s who was referred to our clinic for elevated prostate-specific antigen and presented with mild obstructive lower urinary tract and defecatory symptoms. Prostate needle-core biopsy revealed neoplastic spindle cells that strongly expressed CD34. Cross-sectional imaging demonstrated a 12 cm locally advanced heterogeneous prostate mass with intravesical extension and mass effect on the anterior rectum. Radical cystoprostatectomy with orthotopic neobladder reconstruction was performed, and the diagnosis of primary prostatic SFT was made based on histological characteristics and immunophenotyping. We present diagnostic, clinical management and prognostic considerations in patients with primary prostatic SFT.

Keywords: Pathology; Prostate; Urological surgery; Urology.

Figure 1

CT abdomen/pelvis with intravenous and oral contrast obtained at the time of initial diagnosis. A 12 cm mass is seen arising from the prostate with mass effect on the bladder anteriorly and rectum posteriorly (A–C).

Figure 2

Gross photograph of the cystoprostatectomy specimen showing the relationship between the tumour and the bladder, urethra, seminal vesicles and vas deferens (A). Cross-section of the tumour showing direct extension into the bladder trigone with significant atrophy of the muscularis propria but without mucosal invasion (B). Cross-section of the tumour showing areas of cystic dilatation/degeneration (C).

Figure 3

Low magnification image (H&E) showing areas of cystic dilatation at the periphery, corresponding to the designated area in figure 2C (A). Medium power image (H&E) showing spindle cells infiltrating between residual prostatic glands (B). Low magnification image (H&E) showing the relationship between the tumour (inferior) and the overlying atrophic muscularis propria and urothelial surface (superior), corresponding to figure 2B (C). Medium magnification image (H&E) showing a proliferation of bland oval to spindled cells in a haphazard configuration surrounding prominent staghorn-like vessels (D). High magnification image (H&E) showing bland, round to oval spindled cells with varying amounts of collagen deposition and a notable absence of significant nuclear atypia, increased mitotic activity, apoptotic bodies and necrosis (E).

Figure 4

High magnification of the patient’s SFT showing positivity with CD34, BCL2 and STAT 6 (A, B, C, respectively). High magnification of the patient’s SFT showing no staining with SMA, S100 and progesterone receptor (D, E, F, respectively). SFT, solitary fibrous tumours.