To characterise clinicopathological features and clinical outcomes of the genitourinary tract solitary fibrous tumours, incorporating NAB2–STAT6 gene fusion status.
The presence of the molecular hallmark NAB2–STAT6 gene fusion and for the defining fusion partner product STAT6 was assessed in 11 cases of the genitourinary tract solitary fibrous tumours. NAB2–STAT6 gene fusion analysis was performed using a break-apart fluorescence in situ hybridisation (FISH) probe using a probe cocktail with Bacterial artificial chromosome (BAC) clones for STAT6 and NAB2.
Eleven solitary fibrous tumours were diagnosed in eight male patients and three female patients with a mean age of 46 years (range: 11–64 years). Four of the tumours had malignant histological features, and three were considered moderate risk for metastasis. With a mean follow-up time of 61 months, 1 recurred locally and 2 presented at distant metastatic sites. Using a break-apart FISH probe cocktail, we found the NAB2–STAT6 gene fusion and nuclear STAT6 expression in 58% and 91% of cases, respectively. However, the NAB2–STAT6 fusion status was not correlated with STAT6 expression or useful in discriminating between malignant histological features or subsequent clinical outcomes in the genitourinary solitary fibrous tumours.
A subset of solitary fibrous tumours of the genitourinary tract behaved aggressively. Using a break-apart FISH probe cocktail, we found the NAB2–STAT6 gene fusion in 64% of cases. However, the NAB2–STAT6 fusion status was not correlated with STAT6 expression or useful in discriminating between low-risk or high-risk tumours and subsequent clinical outcomes.