GIST with a twist--upregulation of PDGF-B resulting in metachronous gastrointestinal stromal tumor and dermatofibrosarcoma protuberans.
METHODS
A 61-year-old male was referred following an incidental radiological discovery of an intra-abdominal mass. His medical history included excision of a lumbar dermatofibrosarcoma protuberans (DFSP) 5 years previously. A CT scan of the abdomen revealed a mass arising from the greater curvature of the stomach. Upper GI endoscopy was normal. He underwent successful laparoscopic resection of this mass.


METHODS
The histology of the abdominal mass revealed a gastrointestinal stromal tumor (GIST) with poor prognostic indicators. Immunohistochemical analysis of the GIST and his previous DFSP was performed.


RESULTS
Immunohistochemistry suggested a link between the GIST and his previous DFSP involving the PDGF signalling system.


CONCLUSIONS
Both GIST and DFSP are extremely rare tumors. A mutation in the platelet-derived growth factor receptor alpha (PDGFR-alpha) has been described in 5-15% of GISTs. It has been shown that DFSP is frequently associated with a translocation between PDGF-B (Chr 22) and COL1A1 (Chr 17), causing continuous activation of PDGFR-beta. Literature review confirms that there are no previously reported cases of both of these tumors occurring in the same patient.


CONCLUSIONS
We hypothesize that this patient may have a previously undescribed genetic mutation involving the PDGF signalling system, resulting in these two very rare malignancies. Immunohistochemistry studies confirmed the link on this occasion. Improvements in our understanding of the molecular biology of the PDGF system may novel therapeutic targets in the future.
McCarthy
Colin J
CJ
Department of Surgery, The Royal College of Surgeons in Ireland, Beaumont Hospital, Dublin 9, Ireland. colin.mccarthy@iol.ie
O'Brien
Gavin C
GC
Cummins
Robert J
RJ
Kay
Elaine W
EW
Broe
Patrick J
PJ
D018223:Dermatofibrosarcoma / Q000378:metabolism*; D046152:Gastrointestinal Stromal Tumors / Q000378:metabolism*; D006801:Humans; D008297:Male; D008875:Middle Aged; D016609:Neoplasms, Second Primary / Q000378:metabolism*; D020574:Proto-Oncogene Proteins c-sis / Q000096:biosynthesis*; D020796:Receptor, Platelet-Derived Growth Factor alpha / Q000378:metabolism; D012878:Skin Neoplasms / Q000378:metabolism*; D013274:Stomach Neoplasms / Q000378:metabolism*; D015854:Up-Regulation
D020574:Proto-Oncogene Proteins c-sis; D020796:Receptor, Platelet-Derived Growth Factor alpha