title: Extra-abdominal subcutaneous metastasis of a gastrointestinal stromal tumor: report of a case and a review of the literature.
abstract: Gastrointestinal stromal tumors (GISTs) metastasize primarily within the peritoneal cavity and to the liver. Superficial soft tissue metastases occur in about 1% of advanced GIST and are mostly associated with abdominal laparotomy scars and advanced disease. Extra-abdominal subcutaneous metastases of GIST have not been previously reported. Subcutaneous spindle cell tumors constitute a diagnostic challenge of which the differential diagnostic list can be limited by recognition of morphological, immunohistochemical en molecular genetic patterns. A 69-year-old woman presented with a fast growing subcutaneous nodule on her right upper arm. She was known with an imatinib-resistant advanced GIST, treated with sunitinib. The nodule was excised. Histopathological examination revealed a sharply demarcated tumor nodule in the subcutaneous fat with slightly spindled tumor cells, with pleomorphic nuclei and multiple mitoses. There was a hemangiopericytomatous vascular pattern. The cells stained positive for CD117 (KIT) and CD34. No KIT or platelet-derived growth factor receptor-alpha mutations were detected. We report the first case of an extra-abdominal subcutaneous metastasis of GIST. Although rare, metastatic GIST should therefore be included in the differential diagnosis of subcutaneous spindle cell tumors. A comparative survey of the histological, immunohistochemical and molecular genetic features of spindle cell tumors of the subcutis and a review of the literature is presented.
authors.affiliation: Department of Medical Oncology, Leiden University Medical Center, Leiden, The Netherlands. j.r.kroep@lumc.nl
authors.forename: Judith R
authors.initials: JR
authors.lastname: Kroep
authors.forename: Judith V M G
authors.initials: JV
authors.lastname: Bovée
authors.forename: Aart J
authors.initials: AJ
authors.lastname: van der Molen
authors.forename: Pancras C W
authors.initials: PC
authors.lastname: Hogendoorn
authors.forename: Hans
authors.initials: H
authors.lastname: Gelderblom
mesh_terms: D000368:Aged; D000970:Antineoplastic Agents / Q000627:therapeutic use; D001549:Benzamides; D014408:Biomarkers, Tumor / Q000032:analysis; D001859:Bone Neoplasms / Q000188:drug therapy / Q000556:secondary; D002277:Carcinoma / Q000188:drug therapy / Q000378:metabolism / Q000556:secondary*; D005260:Female; D046152:Gastrointestinal Stromal Tumors / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology*; D006801:Humans; D000068877:Imatinib Mesylate; D007150:Immunohistochemistry; D007211:Indoles / Q000627:therapeutic use; D008113:Liver Neoplasms / Q000188:drug therapy / Q000556:secondary; D010879:Piperazines / Q000627:therapeutic use; D011743:Pyrimidines / Q000627:therapeutic use; D011758:Pyrroles / Q000627:therapeutic use; D012983:Soft Tissue Neoplasms / Q000378:metabolism / Q000556:secondary*; D050151:Subcutaneous Fat / Q000378:metabolism / Q000473:pathology*; D000077210:Sunitinib
chemical_list: D000970:Antineoplastic Agents; D001549:Benzamides; D014408:Biomarkers, Tumor; D007211:Indoles; D010879:Piperazines; D011743:Pyrimidines; D011758:Pyrroles; D000068877:Imatinib Mesylate; D000077210:Sunitinib