Cancer involving the small intestine accounts for approximately 2% of all gastrointestinal malignancies. Adenocarcinoma involving the fourth part of the duodenum is an exceptionally rare entity. It presents with a range of non-specific symptoms and signs, with pre-operative investigations often failing to characterize the nature of the lesion. We report a case of primary adenocarcinoma of the fourth part of the duodenum and highlight the diagnostic and treatment challenges.

A 41-year-old male patient with no significant past medical or surgical history presented to our outpatient department with a 1-year history of progressive abdominal pain and vomiting.

General examination revealed the patient to be underweight and on abdominal examination, there was mild epigastric tenderness with no palpable masses or organomegaly. The patient was previously investigated by upper GI endoscopy, where the scope was passed to the third part of the duodenum. This was essentially normal apart from three areas of mild gastric ulceration. Abdominal ultrasound and CT scanning showed gastric outlet obstruction and barium meal follow-through revealed marked dilatation of the duodenum, with narrowing the duodenojejunal junction.

A provisional diagnosis of gastric outlet obstruction was made, and a diagnostic laparoscopy followed by laparotomy was performed. A small mass obstructing the duodenojejunal junction was identified with marked dilatation of the duodenum (Figure 1). Segmental resection with a 2 cm safety margin, end to side duodenojejunal anastomosis, and feeding jejunostomy distal to the anastomosis was performed (Figure 2). Histopathological examination of the specimen revealed a moderately differentiated adenocarcinoma involving the fourth part of the duodenum (at duodenojejunal junction) (Figure 3 and Figure 4).

The patient made a good postoperative recovery and oral feeding was commenced five days postoperatively and he was discharged on the seventh postoperative day.

At two months postoperatively the feeding jejunostomy was closed after gastrografin meal follow-through, which showed free passage of contrast with neither leakage nor stricture. One year follow-up OGD and CT scan was negative for local or nodal recurrence.

Adenocarcinoma of the duodenum is a rare entity, representing approximately 0.4% of all gastrointestinal malignancies with about 45% of these arising in the third or fourth parts of the duodenum [1],[2]. While risk factors for developing the condition are not fully understood, patients with familial polyposis and Gardner syndrome are considered to have a higher likelihood of developing duodenal cancer [3],[4].

Early diagnosis and treatment of this malignancy is challenged by the fact that patients may present with a range of non-specific symptoms at a relatively late stage in the disease process. Moreover, preoperative investigation may fail to reveal the lesion. In this particular case, CT scan and ultrasound scan (USS) did not identify the lesion and a false negative OGD resulted from an inability to pass the scope through the entire duodenum. These diagnostic challenges have been previously reported in the literature [1], and for this reason, an extended OGD with supporting barium studies and CT scanning seems to be an appropriate means of investigation.

The mainstay of treatment is surgical resection [5]. There is, however, no consensus on the surgical procedure of choice (local excision, segmental resection, or pancreaticoduodenectomy) [6]. In more advanced disease, palliative procedures may be required such as bypasses, stenting, and feeding jejunostomy. The role of chemotherapy and radiotherapy is not well defined. Studies have not shown adjuvant therapy to improve survival significantly [7],[8].

In this case, segmental resection with end to side anastomosis was successfully performed with temporary feeding jejunostomy. Follow-up at one year with OGD and CT scanning did not reveal any local or nodal recurrence. Given the patient’s age, the clear surgical margins and the fact that the tumor was neither high grade nor showing evidence of spread, we expect a good prognosis and survival.

Adenocarcinoma of the fourth part of the duodenum is rare, and patients often present with a long history of non-specific symptoms, sometimes with advanced disease. A high index of suspicion coupled with appropriate investigation and early surgical resection is necessary to manage the disease and improve prognosis. While the cornerstone of treatment is radical surgical resection, prospective studies comparing the different surgical approaches with consideration of the role of chemotherapy are needed to study further the efficacy of the treatment options and their impact on prognosis.