Egists and telocytes

Abstract

Gastrointestinal stromal tumour (GIST) is the most common mesenchymal neoplasm of the gastrointestinal tract and is thought to arise from or show differentiation towards interstitial cells of Cajal (ICC). Increasingly, there are reports of extra-gastrointestinal tumours showing the same morphological, immunohistochemical and genetic features of GISTs. These tumours have been called extragastrointestinal stromal tumours, or EGISTS, and are described in a wide variety of sites. We present the case of a probable EGIST in a 58-year-old gentleman who presented with urinary obstruction. Imaging revealed a 20 cm mass arising from the prostate. Biopsy showed a spindle cell neoplasm with expression of CM 17, DOG1 and CD34. Molecular studies of the KIT gene showed a mutation in exon 11. We discuss some of the theories behind the possible development of EGISTs and the description of ICC-like cells, dubbed telocytes by some groups, outside of the gastrointestinal tract.