Cutaneous hyperpigmentation and familial gastrointestinal stromal tumour associated with KIT mutation

Summary Gastrointestinal stromal tumours ( GIST s) are mesenchymal tumours arising in the gastrointestinal tract. Early detection, before metastasis occurs, is important as complete surgical excision achieves cure. Approximately 85% of GIST s are associated with mutations in the KIT gene, and although the majority of GIST s are sporadic, familial GIST s have been identified. Several families with multiple GIST tumours have also been described with various cutaneous findings including hyperpigmentation, multiple lentigines, vitiligo and urticaria pigmentosa. We discuss a 6‐year‐old boy who presented with an unusual pattern of hyperpigmentation in association with a family history of GIST . A causative KIT mutation was identified in DNA from the pigmented skin and from the resected GIST , and the patient was referred to the Paediatric Gastroenterology department for GIST screening. The term ‘ GIST cutaneous hyperpigmentation disease’ has been suggested previously for the association of familial GIST with cutaneous hyperpigmentation caused by a germline KIT mutation.