Arterio-venous Malformation Masquerading as Small Bowel Mass; A Rare Presentation of Overt GI bleeding

A 76-year-old female with history of ESRD on hemodialysis, diverticulosis on colonoscopy 1 year prior, hypertension, diabetes, and hyperlipidemia presented with a three-week history of fatigue, black stools, and left upper quadrant abdominal pain. She denied nausea, vomiting, or NSAID use. Medications included aspirin 81mg daily and Tylenol as needed for abdominal pain. Upon arrival, vital signs stable, however digital rectal examination revealed melena. Laboratory tests were significant for hemoglobin of 5.7 g/dL (baseline ~10 g/dL), platelet count of 174x10^3/μL, BUN of 27 mg/ dL, creatinine of 3.31 mg/dL, lactate of 1.2 mmol/L, hsTroponin of 14 ng/L, and INR of 0.9. Patient received two units of packed red blood cells and was started on Protonix drip.

Initial workup consisted of an esophagogastroduodenoscopy (EGD), which revealed mild erythematous mucosa without bleeding at the incisura, gastric antrum, and pylorus. Biopsies with further pathology results were unremarkable. A follow-up video capsule endoscopy demonstrated a ~1cm mass in the jejunum with ulceration at the tip and stigmata of recent bleeding (Figure 1). Subsequently, a double balloon enteroscopy (DBE) confirmed a 13mm submucosal ulcerated mass in the proximal to mid-jejunum (Figure 2). Biopsies of the mass were taken using a cold forceps for histology, which triggered brisk bleeding. Hemostasis was achieved by placing two hemostatic clips. Given the presence of the jejunal mass and the uncertainty surrounding its nature, the surgical oncology team was consulted. A CT abdomen and pelvis was then performed, showing focal enhancement and wall thickening with adjacent clips in a loop of bowel, likely corresponding to the recently biopsied jejunal mass (Figure 3). Based on the presentation and imaging findings suggesting a cancerous mass, surgical resection was performed. The jejunal mass and two associated lymph nodes in the surrounding mesentery were excised without complications.

The DBE biopsy showed no evidence of celiac disease, viral cytopathy, metaplasia, parasites, neoplasia, or dysplasia. Gastrointestinal stromal tumor and neuroendocrine tumor were also ruled out. The subsequent bowel resection biopsy revealed dilated blood vessels in the mucosal and submucosal layers, consistent with angiodysplasia/vascular ectasia or AVM. The resection margins were normal, and reactive lymph nodes were observed (Figure 4). Following surgical resection of the AVM, the patient’s melena symptoms completely resolved during the followup period.

Discussion: OGIB presents diagnostic and management challenges as the underlying cause is often not immediately apparent [6]. There are two subtypes of OGIB: obscure- occult bleeding and obscure-overt bleeding. Obscure-occult bleeding is characterized by positive fecal occult blood testing or iron deficiency anemia without visible signs of bleeding. Obscure- overt bleeding involves recurrent or persistent visible bleeding, such as melena or hematochezia, without a definitive identified source using standard diagnostic tests [7]. Although a comprehensive evaluation, including history, physical, endoscopy, and imaging, is crucial for diagnosing OGIB, they are limited in detecting small bowel lesions.

Fortunately, advancements in non-invasive diagnostic modalities, such as video capsule endoscopy (VCE), balloon-assisted enteroscopy (BAE), spiral enteroscopy, and CT enterography (CTE), have revolutionized the approach to diagnosing and managing OGIB (Pasha et al., 2008). VCE offers a noninvasive assessment of the entire small bowel, while BAE enables deeper examination of the small bowel specifically. Radiologic techniques like CTE, tagged red blood cell scintigraphy, and CT angiography assist in localizing and diagnosing bleeding sources. In cases of persistent overt OGIB despite extensive evaluations, intraoperative enteroscopy is considered as a last resort [8].

Several published case studies highlight the diagnostic and management challenges of OGIB. Gralnek et al. (2005) presented a case of recurrent GI bleeding, utilizing multiple diagnostic modalities to diagnose and surgically resect a carcinoid tumor. Ng et al. [9] reported a case of upper GI bleeding caused by gastric AVM, emphasizing the need to consider AVM as a potential cause. Poon and Poon [10] described a challenging case of massive GI bleeding initially misdiagnosed as a duodenal varix but later identified as a duodenal AVM, underscoring the significance of early angiography and surgical excision in unstable patients. Gong et al. [11] reported a case of jejunal AVM initially mistaken for a gastrointestinal stromal tumor, further highlighting the difficulties in diagnosing AVMs.