Solitary fibrous tumour: a diagnostic dilemma.

Solitary fibrous tumour (SFT) is a rare spindle cell neoplasm arising at pleural and extrapleural sites. Five cases of SFT diagnosed at our institution over a five year period were reviewed. Haematoxylin and eosin stained histological sections, immuno-histochemical markers including CD34 and electron microscopy were the different methods used to study these tumours. Three histological features were consistently observed in all the tumours: the tumours were composed of short spindle cells separated by dense collagen bands and arranged in alternate hypocellular and hypercellular areas. CD34 positivity was seen in all the cases. SFT's have been reported to behave in an unpredictable fashion and hence prolonged follow up is essential. Histology, CD34 positivity and electron microscopy are useful tools in diagnosing SFT. While the pleural tumours can be diagnosed based on histology, this must be substantiated by ancillary techniques in case of extrapleural tumours.