Familial multiple gastrointestinal stromal tumours with associated abnormalities of the myenteric plexus layer and skeinoid fibres

Aims: Multiple familial gastrointestinal stromal tumours are rare. We repor t the third family with two cases of multiple gastrointestinal stromal tumo urs showing skeinoid fibres. Associated abnormalities of the myenteric plex us layer are described and new hypotheses for the histogenesis of gastroint estinal stromal tumours are formulated. Methods and results: Multiple gastrointestinal stromal tumours developed in the duodenum and proximal jejunum were removed from mother and son. No his tory of a specific syndrome or of mastocytosis was known. Light microscopy revealed typical gastrointestinal stromal tumours with skeinoid fibres. An unusual abnormality of the myenteric plexus layer, showing a diffuse spindl e cell hyperplasia. was noted in the macroscopically normal digestive wall. No abnormalities of the ganglion cells were associated. Tumours and the sp indle cell hyperplasia showed similar morphological and immunohistochemical features with expression of CD34 and CD117 antigens. Follow-up revealed re currences in the mother. Conclusion: The morphological characteristics of these two cases of familia l gastrointestinal stromal tumours and of the associated abnormalities of t he myenteric plexus layer, help to better explain the histogenesis of multi ple familial gastrointestinal stromal tumours. The hyperplasia of the myent eric plexus could be considered a risk factor for recurrent tumours.