title: Collision tumour involving a rectal gastrointestinal stromal tumour with invasion of the prostate and a prostatic adenocarcinoma.
abstract: BACKGROUND
  Gastrointestinal stromal tumours (GISTs) are the most common primary mesenchymal neoplasia in the gastrointestinal tract, although they represent only a small fraction of total gastrointestinal malignancies in adults (<2%). GISTs can be located at any level of the gastrointestinal tract; the stomach is the most common location (60-70%), in contrast to the rectum, which is most rare (4%). When a GIST invades into the adjacent prostate tissue, it can simulate prostate cancer. In this study, we report on a case comprising the unexpected collision between a rectal GIST tumour and a prostatic adenocarcinoma.
  
  
  RESULTS
  We describe the complexity of the clinical, endoscopic and radiological diagnosis, of the differential diagnosis based on tumour biopsy, and of the role of neoadjuvant therapy using imatinib prior to surgical treatment.
  
  
  CONCLUSIONS
  Although isolated cases of coexisting GISTs and prostatic adenocarcinomas have previously been described, this is the first reported case in the medical literature of a collision tumour involving a rectal GIST and prostatic adenocarcinoma components.
  The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/1238437468776331.
authors.affiliation: Unidad de gestión clínica de Oncohematología y Anatomía Patológica, Hospital Universitario de Valme, Carretera de Cádiz s/n, 41014, Sevilla, Spain. laura.macias.garcia@gmail.com
authors.forename: Laura
authors.initials: L
authors.lastname: Macías-García
authors.forename: Haydee
authors.initials: H
authors.lastname: De la Hoz-Herazo
authors.forename: Antonio
authors.initials: A
authors.lastname: Robles-Frías
authors.forename: María J
authors.initials: MJ
authors.lastname: Pareja-Megía
authors.forename: Juan
authors.initials: J
authors.lastname: López-Garrido
authors.forename: José I
authors.initials: JI
authors.lastname: López
mesh_terms: D000230:Adenocarcinoma / Q000737:chemistry / Q000473:pathology* / Q000628:therapy; D000970:Antineoplastic Agents / Q000627:therapeutic use; D001549:Benzamides / Q000627:therapeutic use; D014408:Biomarkers, Tumor / Q000032:analysis; D001706:Biopsy; D017024:Chemotherapy, Adjuvant; D003937:Diagnosis, Differential; D046152:Gastrointestinal Stromal Tumors / Q000737:chemistry / Q000473:pathology* / Q000628:therapy; D006801:Humans; D000068877:Imatinib Mesylate; D007150:Immunohistochemistry; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D020360:Neoadjuvant Therapy; D009361:Neoplasm Invasiveness; D009378:Neoplasms, Multiple Primary / Q000737:chemistry / Q000473:pathology* / Q000628:therapy; D010879:Piperazines / Q000627:therapeutic use; D011237:Predictive Value of Tests; D011467:Prostate / Q000737:chemistry / Q000473:pathology* / Q000601:surgery; D011468:Prostatectomy; D011471:Prostatic Neoplasms / Q000737:chemistry / Q000473:pathology* / Q000628:therapy; D011743:Pyrimidines / Q000627:therapeutic use; D012004:Rectal Neoplasms / Q000737:chemistry / Q000473:pathology* / Q000628:therapy; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome
chemical_list: D000970:Antineoplastic Agents; D001549:Benzamides; D014408:Biomarkers, Tumor; D010879:Piperazines; D011743:Pyrimidines; D000068877:Imatinib Mesylate