An unexpected cause of proximal small intestinal obstruction

A 63-year-old caucasian male with history of tonsil cancer, under induction chemotherapy, reported food intolerance and vomiting with duration of one month. Symptoms had increased over the last days and were associated with a weight loss of 10 Kg during the past three months. The patient lived all of is life in an urban environment. General physical examination revealed cachexia and dehydration. Gastrointestinal symptoms persisted despite intravenous pantoprazole, prokinetic drugs and nasogastric tube insertion. On investigation, patient presented normocytic and normochromic anemia (9.2 g/dL), lymphocytosis (11.78 x109/L) with neutrophilia (70.7%) and eosinophilia (7.7%), hypoalbuminemia (2.8 g/dL) and elevated C-reactive protein (25.5 mg/dL). Upper endoscopy revealed deformation of bulb and second part of the duodenum with mucosal edema, superficial ulceration and friability (Figure 1a). Biopsies were taken from the bulb and second portion of the duodenum. Computer tomography demonstrated gastric distention, duodenal wall thickening and lumen narrowing in the second and third portion of the duodenum (Figure 2). These findings were indicative of a functionally relevant duodenum stenosis. Histopathologic evaluation of biopsy specimens from the duodenum revealed moderate accumulation of eosinophilic granulocytes and nematode larvae within mucosal crypts (Figure 1b). What is the diagnosis?