Case Presentation:

A 50–year–old male with a history of dyslipidemia was evaluated at an outside hospital for abdominal pain, constipation, and intractable nausea and vomiting for five days prior to admission. The pain was crampy and diffuse and had recently worsened. Last flatus and bowel movement were five days prior to presentation. He denied fevers, weight loss and previous abdominal surgeries. Physical exam revealed a moderately distended abdomen, mild diffuse abdominal tenderness without guarding or rebound tenderness and hypoactive bowel sounds. No hernias were found. Laboratory values were significant for mild hypokalemia and normal WBC count, amylase, lipase, and lactate levels. An abdominal X–ray and subsequent CT abdomen/pelvis revealed a high–grade distal small bowel obstruction (SBO). Incidentally, an anterior mediastinal mass was partially visualized. Patient underwent an exploratory laparatomy and subsequent lysis of adhesions. Post–operatively, his hospital course was complicated by persistent nausea, vomiting, and inability to tolerate clears. Repeat abdominal imaging revealed dilated small bowel loops and a persistent ileus without evidence of obstruction. There was no clinical or radiographic improvement with nasogastric tube decompression, antiemetics or pro–motility agents. Further workup including an upper endoscopy revealed only moderate gastritis. To better evaluate the mediastinal mass, an MRI chest was performed and revealed a large anterior mediastinal mass concerning for thymoma. He underwent surgical removal of the mediastinal mass and pathology subsequently confirmed a WHO type B1 thymoma. One week after his thymectomy, he regained normal bowel function and was able to tolerate a regular meal.

Discussion:

Acute intestinal pseudo–obstruction is often seen in severely ill, hospitalized patients with multiple comorbidities. It is most often associated with nonmalignant etiologies including adhesions from abdominal surgeries, diabetes, thyroid disorders, narcotic usage, infections, and collagen vascular diseases. However, it has been associated with pheochromocytoma and small cell carcinoma as well. Intestinal pseudo–obstruction, as a paraneoplastic manifestation of malignant thymoma, has been rarely reported in the medical literature. In this patient, clinical signs of obstruction persisted after lysis of adhesions and only surgical removal of the thymoma resulted in restoration of this patient’s bowel function, strongly suggesting a correlation between the two.

Conclusions:

The purpose in reporting this case is to increase clinician awareness of the rare association between malignant thymoma and intestinal pseudo–obstruction. Although largely considered to be due to benign etiologies, malignant thymoma should be considered in the differential diagnosis of conditions associated with intestinal pseudo–obstruction.