Revision of Gastrointestinal Mesenchymal Tumors
Pattana Sornmayura MD*, Jatuwit Howannapakorn MD*, Patcharee Karnsombut Cert MLT*
Affiliation : * Department of Pathology, Faculty of Medicine, Ramathibodi Hospital, Mahidol University, Bangkok, Thailand
Background : Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumor of the
gastrointestinal (GI) tract. The advent of target therapy (imatinib mesylate) for GISTs increases the importance
of pathologic diagnosis. The previous diagnosis with smooth muscle tumor (leiomyoma or leiomyosarcoma)
and nerve sheath tumor (schwannoma) become GISTs after the study with CD117 immunohistochemistry
accompanying conventional histologic study in many series.
Objective : To identify the incidence of GISTs in the patients who were previously diagnosed with smooth
muscle or nerve sheath tumors. The histology and immunoreactivity of both newly found and previously
diagnosed with GISTs are also studied.
Material and Method: A retrospective database identified all patients seen from 1998 to 2006. Patients with
mesenchymal tumors of the GI tract and intraabdominal extragastrointestinal tract were selected, 53 cases in
total. Clinical and pathological data, treatment, and outcome were analyzed.
Results : After revision, the total number of GISTs is 42 cases. There were 33 cases previously diagnosed with
leiomyosarcoma that became the diagnosis with GISTs (31 cases or 93.9%), due to CD117 positivity. Most of
GISTs cases had spindle cell type (26 cases, 61.9%) and only the colon and omentum had predominant mixed
cell type.
Conclusion : GISTs are the most common mesenchymal neoplasm of the stomach and small intestine and are
relatively less frequent at other gastrointestinal sites. An increasing awareness of their histologic,
immunophenotypic, and molecular features coupled with an evolving understanding of their histogenesis is
facilitating our ability to identify these tumors.
Keywords : Gastrointestinal stromal tumors ( GISTs ), c-kit, CD117, Leiomyoma, Leiomyosarcoma, Schwannoma, Tyrosine kinase inhibitor, Imatinib mesylate
