Neuromuscular and Vascular Hamartoma of the Small Intestine: An Exuberant Reparative Process Secondary to Chronic Inflammation.

The term Neuromuscular and Vascular Hamartoma (NMVH) was initially coined by Fernando and McGovern in 1982 in their report of 2 cases. Whether this lesion is truly hamartomatous or represents a "burnt-out" phase of varying chronic pathologies has been debated since that time. Examples of NMVH-like proliferations have been reported in the setting of diaphragm disease, Crohn's disease, radiation, and ischemia. Herein we present the case of a 73-year-old female with partial small bowel obstruction and a past surgical history significant for cholecystectomy and abdominal hysterectomy. A computed tomography scan revealed an ill-defined mass with the same density as muscle extending into the mesentery, worrisome for malignancy and generating the differential of lymphoma versus metastatic disease. Upon laparotomy, a 2.5 cm, constrictive, predominantly mural-based mass was identified. The more proximal bowel was dilated, and there were dense serosal adhesions. Grossly, the transmural lesion had a tan-yellow cobweb-like cut surface and the overlying mucosa was flattened. Histologically, the lesion contained fascicles of smooth muscle, irregularly spaced large nerve bundles, and thick-walled vasculature in a haphazard arrangement within a hypocellular fibroadipose stroma. No stigmata of Crohn's disease were observed, and the uninvolved enteric tissue was unremarkable. The patient's medical history was negative for chronic nonsteroidal anti-inflammatory use and was otherwise unremarkable. This case of an NMVH-like lesion is presented as a reminder of benign mass-forming lesions causing bowel obstruction and suggests that such lesions may develop secondary to a chronic inflammatory process.