Plexiform fibromyxoma of the small bowel: A case report

Abstract

Background: Plexiform fibromyxoma is a rare, special type of mesenchymal tumor. The most common presenting symptoms are anemia, hematemesis, and hematochezia, without sex or age predilection. The reported cases have mainly occurred in the gastric antrum and pylorus region, with some cases in the duodenum.

Case summary: We report here a case of plexiform fibromyxoma in the upper segment of the jejunum, which was continuously followed up for 3 years after surgical removal. Plexiform fibromyxoma showed multinodular or plexiform growth. The cells in the tumor node were spindle-shaped but few in number and mitotic figures. Small blood vessels and mucous matrix were found among the tumor cells. Immunohistochemistry revealed that the plexiform fibromyxoma cells were positive for smooth muscle actin, focally positive for CD10, and negative for cytokeratin, CD117, DOG-1 (discovered on GIST-1) desmin, S-100, epithelial membrane antigen, and CD34. Ki-67 labeling index was < 5%. Plexiform fibromyxoma showed benign biological behavior. After 3 years of consecutive postoperative follow-up, no obvious signs of metastasis or recurrence were found by imaging examination.

Conclusion: Plexiform fibromyxoma is a rare type of mesenchymal tumor. The diagnosis mainly depends on pathological examination, and it should be distinguished from other gastrointestinal mesenchymal tumors.

Keywords: Benign tumor; Case report; Gastrointestinal stromal tumor; Plexiform angiomyxoid myofibroblastic tumor; Plexiform fibromyxoma; Small bowel.

Figure 1

Capsule endoscopy revealed a protuberant lesion in the upper segment of the jejunum; the margin of which was unclear. Ulceration was found at the top (arrow).

Figure 2

Results of single balloon colonoscopy. A protuberant lesion in the upper segment of the jejunum. Ulceration was found at the top.

Figure 3

The diagnosis of small intestinal plexiform fibromyxoma. A: Myxoid nodules and extensive hemorrhagic areas. The stroma was rich in small vessels (HE × 40); B: Tumor showed multinodular or plexiform growth, paucicellular nodules with blunt spindle cells and myxoid stroma (HE, × 40); C: Spindle-shaped bland tumor cells were separated by an abundant intercellular myxoid or fibromyxoid matrix (HE, × 100); D: Tumor SMA(+) (× 40); E: Tumor SMA(+) (× 100); F: Ki-67 labeling index < 5% (× 100). HE: Hematoxylin and eosin; SMA: Smooth muscle actin.