Greater omentum gastrointestinal stromal tumor with PDGFRA-mutation and hemoperitoneum

Figure 1 Contrast-enhanced axial (A) and coronal (B) abdominal computed tomography. A huge mass was seen in the right abdominal cavity showing internal heterogeneity, with some high density area, but comprised mostly of low density regions which seemed to be a cystic component or interstitial mucous. The high density area was not enhanced, thus hemorrhage was suggested. Moreover a large amount of bloody ascites was seen in the pelvic cavity.

Figure 2 Gross appearance of the resected specimen. A: The tumor appeared as a dark-red, relatively hard mass mixed with partly bleeding blood clots; B: The cut surface of the tumor showed cystic degeneration, and focal hemorrhage.

Figure 3 Histopathological findings of the resected specimen of the tumor. A and B: The tumors were characterized by epithelioid-shaped cells and showed high cellularity (HE staining, A: × 40, B: × 200); C: Immunostaining of CD117 (KIT) was positive; D: Immunostaining of CD34 was positive (C, D: × 200).

Figure 4 Representative sequencing results of omentum gastrointestinal stromal tumor. This case showed a codon 846 (Asp to Glu) substitution, and a codon 848 (Asn to Lys) substitution within exon 18 of PDGFRA gene.