Nodular Sclerosing Mesenteritis: An Occasional Finding Mimicking a Spindle Cell Tumor

BACKGROUND The term "sclerosing mesenteritis" includes a spectrum of rare idiopathic diseases involving the small and/or large bowel. It appears as a diffuse, localized, or multinodular thickening of the mesentery, with a variable degree of chronic non-specific inflammation, fat necrosis, and fibrosis. CASE REPORT Here, we report a case of 83-year-old woman with symptoms of intestinal occlusion, vomiting, and abdominal pain. Radiographic examinations showed air fluid levels in right and left quadrants and in the mesogastric site, while computed tomography (CT) documented a strangulated inguinal hernia with ileal obstruction. Based on clinical examination and radiologic findings, the patient underwent surgery for inguinal hernia reduction. The examination of viscera revealed 2 tracts of ileum with ischemic signs and covered by fibrin; thus, the 2 intestinal loops were resected. Histological examination revealed chronic non-specific inflammation of the whole intestinal wall, including the subserosa in the resected tract of proximal ileum, while the distal ileal loop (not herniated tract) showed a subserosal fibrous nodule of 2 cm in greatest diameter, composed of a proliferation of spindle cells haphazardly arranged in a collagenized stroma. The diagnosis of sclerosing mesenteritis was rendered. CONCLUSIONS The present case shows the possibility of an incidental diagnosis during another intervention such as hernia surgery. Pathologists should be aware of this disease to avoid confusion with aggressive tumors such as intra-abdominal desmoid-type fibromatosis and gastrointestinal stromal tumor.