Removing a solid-cystic intraabdominal desmoid tumor at a gastro-pancreatic lesion

Background

Desmoid tumors (also called aggressive fibromatosis, deep musculoaponeurotic fibromatosis) are locally aggressive tumors with no potential for metastasis or dedifferentiation. Radiologically, they are usually non-specific, slow-growing solid masses that are difficult to distinguish from other soft tissue tumors, but they rarely show cystic lesions. Sporadic desmoid tumors can occur at any site in the body, and anatomic locations are classified into 3 regions: trunk/extremity, abdominal wall, and intraabdominal. Complete surgical resection is the only curative option, but intraabdominal desmoid tumors are often unresectable, because they often infiltrate the mesentery. Here, we report a case of an intraabdominal desmoid tumor that occurred at a gastro-pancreatic lesion with cystic features, and presents the successful laparoscopic resection of the tumor.

Case presentation

An intraabdominal cystic mass was incidentally detected between the stomach and the pancreas in a 52-year-old woman undergoing postoperative follow-up computed tomography (CT) for chondrosarcoma of a rib. Her family history was unremarkable. Blood counts and serum biochemistry results were within normal limits. An abdominal CT scan revealed a 20 × 18-mm well-defined cystic mass with a solid component (Fig. 1a,b). The tumor was adjacent to the stomach and the pancreas body, but there was no sign of invasive growth to the organs. MRI showed a cystic mass with high intensity on T2-weighted images and low intensity on T1-weighted images. The lesion showed no sign of diffusion restriction by diffusion-weighed MRI. The solid component of the cystic wall was gradually enhanced in the late phase. Subsequent endoscopic ultrasonography (EUS) showed an 18 × 13 mm round cystic mass, with a heterogeneous nodular lesion at the side of the serosa of the stomach (Fig. 1c). Esophago-gastric endoscopy showed no local lesion on the mucosal surface of the stomach (Fig. 1d). An intraabdominal tumor was suspected, but it was difficult to determine the specific diagnosis.

Laparoscopic resection via 5 trocars was performed with the patient in the supine position. After the gastro-colic ligament was cut, the omental bursa was opened widely. The tumor was confirmed at the superior border of tghe pancreas body, and adhered to the posterior wall of the stomach (Fig. 2a). With careful dissection, the left gastric artery and vein were isolated and preserved. The tumor was cut from the stomach by wedge resection of the gastric wall using a linear stapler (Fig. 2b). Then, we performed a spleen-preserving distal pancreatectomy. The pancreas body-tail was carefully mobilized and separated from the splenic artery and vein by dissecting the small vessels. The pancreas was dissected at the right side of the tumor using a linear stapler (Fig. 2c). We performed a complete laparoscopic excision, and the spleen and splenic vessels were completely preserved (Fig. 2d). The operative time was 279 min, and intraoperative blood loss was 15 mL. The postoperative course was uneventful, and the patient was discharged healthy.

Macroscopic examination of the resected specimen revealed a capsulated cystic mass measuring approximately 20 mm with serous content. The whitish solid nodule containing the cystic lesion existed at the wall of the stomach (Fig. 3a). Microscopic examination demonstrated the distribution of spindle tumor cells, partly arranged in a fascicular fashion and accompanied by a collagenous stroma (Fig. 3b, c). Mitotic figures were rarely seen. The tumor cells were attached to the muscular layer of the gastric wall (Fig. 3b). A benign cystic lesion was also observed, but its origin was not determined. Immunohistochemically, the spindle cells were diffusely positive for β-catenin protein in the nucleus (Fig. 3d), but negative for theα-SMA, desmin, S-100, c-kit, and CD34 proteins. These findings were consistent with the diagnosis of intraabdominal desmoid tumor.