Gastrointestinal stromal tumor - massive

Case contributed by Yaïr Glick
Diagnosis certain


Left lower quadrant pain, fever, increased inflammatory markers.

Patient Data

Age: 55 years
Gender: Male

Huge mass in the central abdomen measuring 19.3 x 12.5 x 20.5 cm (LL x AP x CC), displaying significant central necrosis, several specks of calcification, and a large cavity with an air-fluid (i.e. dilute contrast material) level. Abutting the mass in the left lower abdomen is an edematous loop of small bowel with edematous mesentery. Several implants/metastatic lymph nodes in the left abdomen, virtually all of which display a necrotic center. Fat stranding in the right part of the greater omentum.

Single diverticulum in proximal ascending colon, single diverticulum in distal descending colon, and few diverticula in proximal sigmoid colon; no sign of inflammation.
Numerous small liver cysts.
Mesenteric panniculitis.
The appendiceal lumen is filled with very hyperdense (calcific?) material.

Case Discussion


Massive intraperitoneal neoplastic mass measuring ~15 cm in diameter, stuck to a small bowel loop 60 cm from the ligament of Treitz (not appearing to penetrate it), to the mesocolon and to the omentum. Impressive lymphadenopathy along the mesentery, the mesocolon, and the omentum. En bloc resection of the mass, a 5-cm segment of small bowel, and omentum. Resection of several large nodes along the mesentery having the appearance of large lymph nodes.


Macroscopic description:
Two pieces of tissue - the first is of a node appearance 1.7 cm in diameter, the second 4 cm in diameter containing an incision 2 cm in length, having the appearance of a node/partially hemorrhagic cyst.
A segment of small bowel 10 cm in length and 4 cm in diameter, closed at the sides with a row of clips. Abutting it is a sac-shaped mass 21 cm in diameter and cystic in appearance, on its external surface adhesions are visible. On incision, there is hemorrhagic content in the cavity and friable orange-colored tissue adherent to the wall, partially ulcerated/fibrotic/reaching the radial margins. On opening of the bowel segment, 3 cm from its edge there is a bowel wall perforation measuring 1.5 cm in diameter into the cystic cavity underneath. The rest of the mucosa is edematous.

Microscopic description:

  1. Peritoneum: nodal metastases of gastrointestinal stromal tumor seen (the largest one 4 cm in diameter)
  2. Omentum: tumor nodules of gastrointestinal stromal tumor seen in the omental tissue.
  3. Small intestine (resection): gastrointestinal stromal tumor 21 cm in greatest diameter with high risk of malignancy, foci of necrosis, calcifications. Immunostains: c-KIT and DOG-1 are positive, smooth muscle actin partly positive. Desmin, S-100, and pankeratin are negative.
  4. Tumor present at the radial resection margins. Proximal, and distal margins free. Lymph nodes: seven tumor nodules seen in the peri-intestinal fat, probably all or part of them effaced lymph nodes (effacement = destruction of normal nodal architecture).

So the reason for the air-fluid level in the tumor cavity (see Findings) was a perforation in the overlying small bowel wall.

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