Fine needle aspiration appearance of extragastrointestinal stromal tumor. A case report.
BACKGROUND
Gastrointestinal stromal tumors (GISTs) rarely develop outside the digestive tract and in the soft tissues of abdomen and retroperitoneum. Such tumors are designated extra-GISTs (EGISTs). Cytologic and immunocytochemical features of a case of EGIST are reported.


METHODS
A 54-year-old woman presented with a peritoneal mass, diameter 22 cm, adherent to the omentum and without a connection to the digestive tract. Fine needle aspiration biopsy (FNAB) of the excised tumor showed high cellularity in two patterns: monotonous spindle cells were intermingled with a mildly atypical epithelioid component. Immunocytochemistry performed on cytospins revealed reactivity for c-kit (CD117), CD34 and smooth muscle actin and negativity for S-100. The findings were concordant with a histologic diagnosis of EGIST.


CONCLUSIONS
EGISTs are infrequent neoplasms and can be diagnosed in FNAB samples. The clinical/radiologic setting must be considered together with the cytologic features. Immunocytochemistry is a clue to the diagnosis when it detects c-kit reactivity.
Ortiz-Rey
José A
JA
Department of Pathology, Policlínico de Vigo, S.A., Vigo, Pontevedra, Spain. jaortiz@povisa.es
Fernández
Gabriel C
GC
Magdalena
Carlos J
CJ
Alvarez
Carlos
C
Antón
Iosu
I
San Miguel
Pilar
P
de la Fuente
Ana
A
D000008:Abdominal Neoplasms / Q000737:chemistry / Q000473:pathology* / Q000601:surgery; D000199:Actins / Q000032:analysis; D018952:Antigens, CD34 / Q000032:analysis; D014408:Biomarkers, Tumor / Q000032:analysis; D001707:Biopsy, Needle / Q000379:methods*; D005260:Female; D005770:Gastrointestinal Neoplasms / Q000737:chemistry / Q000473:pathology* / Q000601:surgery; D006801:Humans; D007150:Immunohistochemistry; D008875:Middle Aged; D009852:Omentum / Q000737:chemistry / Q000473:pathology / Q000601:surgery; D010534:Peritoneal Neoplasms / Q000737:chemistry / Q000473:pathology* / Q000601:surgery; D019009:Proto-Oncogene Proteins c-kit / Q000032:analysis; D017154:Stromal Cells / Q000737:chemistry / Q000473:pathology; D014057:Tomography, X-Ray Computed
D000199:Actins; D018952:Antigens, CD34; D014408:Biomarkers, Tumor; D019009:Proto-Oncogene Proteins c-kit