From KIT-mutated into wild-type: dedifferentiation of gastrointestinal stromal tumor in adolescent patient-a case report

Background: Gastrointestinal stromal tumor (GIST) is the most common mesenchymal neoplasm of the gastrointestinal tract, usually found in elderly adults. It is infrequent among pediatric patients and usually differs from adult-type disease in terms of histopathology and molecular features.Case Description: We describe the management of the disease in a 10-year-old female patient diagnosed with a GIST of the stomach. In total, she has undergone successively total tumor resection, unsuccessful imatinib treatment and subtotal gastric resection at relapse. The first genetic test from primary tumor confirmed KIT mutations in exons 13 and 17, while the repeated genetic screening using tumor sample from subtotal gastric resection revealed no KIT or PDGFRA genes mutations. Such dedifferentiation from adult type (thus KIT-mutated) into wild-type (without KIT or PDGFRA mutation) has not been reported so far to the best of our knowledge. Currently, the patient is observed, and no further pharmacological nor surgical treatment has been administered.Conclusions: The case underlines the importance of genetic profiling combined with non-standard diagnostics (both histopathological and radiological) due to the treatment efficacy prediction. We moreover emphasize the necessity to create worldwide standards on the diagnostics and treatment of GIST in pediatric patients that would include options of targeted therapies.

Automated summary

This article describes the management of a 10-year-old female patient diagnosed with gastrointestinal stromal tumor (GIST) of the stomach. The patient underwent tumor resection, imatinib treatment, and gastric resection at relapse. The genetic mutation in the patient changed from KIT mutation to wild-type, which has not been reported in pediatric patients before. The importance of genetic profiling and non-standard diagnostics in predicting treatment efficacy is highlighted, as well as the need for global standards in the diagnosis and treatment of pediatric GIST.