Adenocarcinoma of the appendix: a rural experience

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Tumours of the appendix are rare and constitute less than 0.5–1% of all gastrointestinal tumours and an estimated incidence of 1% of all appendicectomies.1 Tumours of the appendix may present with acute appendicitis, abdominal distension 18% (including malignant ascites or mucinous ascites known as pseudomyxoma peritonei), palpable mass 30% or abdominal pain 56%.3 Frequently, appendiceal tumours are an incidental finding on imaging or during unrelated abdominal surgery (20%).5
Adenocarcinomas of the appendix (ACA) constitute roughly one‐third of tumours of the appendix, carcinoid being the most common. ACAs are divided into three histological subtypes: mucinous (56.1%), intestinal or colonic (37.5%) and signet cell (6.4%).6
A 52‐year‐old man presented to a rural emergency department with sudden onset of severe right‐sided abdominal pain radiating to the right flank for 3 days on a background of dull constant pain in the right side of the abdomen over the previous 3 weeks. There were no associated symptoms such as fever, nausea, vomiting, bowel disturbances or weight loss. No significant past medical history, no previous colonoscopies and no family history of bowel cancer.
On examination, observations were within normal limits. There was a palpable mass in the right lower abdomen, which was tender with localized guarding and percussion tenderness. Digital rectal examination was normal. Bloods were unremarkable with white cell count of 11.4, C‐reactive protein 21 and normal liver and renal functions.
A computed tomography (CT) scan was undertaken, which showed a thick walled cystic lesion abutting the caecum (Fig. 1), possibly arising from the appendix measuring 7.7 × 1.6 × 12.6 cm, multiple small foci of calcification present in the wall of the lesion and fluid present in the right paracolic gutter (Fig. 2).
A preoperative diagnosis of an appendiceal tumour is uncommonly made, often being a histological diagnosis, not appreciated at time of surgery. This case differs in the differential diagnosis of appendiceal malignancy and was considered preoperatively due to the presence of a large mucocele containing foci of calcification.
Entertaining the differential of ACA gave a rare chance to pre‐plan the definitive surgery following discussions with colorectal specialists at a tertiary centre multidisciplinary team meeting. A right hemicolectomy was recommended in line with current recommendations that patients found to have ACA undergo a right colectomy with oncological clearance/debulking of any intra‐abdominal disease, as retrospective studies have shown that survival rates are higher with right colectomy over appendectomy alone.6
Intraoperatively, a large inflamed cystic structure was found that originated from the base of the appendix and extended in the retroperitoneal plane to the lower edge of the liver (Fig. 3). A perforation approximately 2 cm from the base of the appendix was present with pseudomyxoma peritonei (PMP) present as thick gelatinous mucus, contained in the right side of the abdomen. Dissection was made difficult by presence of inflammation and fibrosis. The mass was widely resected, a right hemicolectomy was performed. Extensive peritoneal lavage with warm sterile water was undertaken as was irrigation of the wound once the rectus sheath was closed.
Histopathology reported a high‐grade mucinous adenocarcinoma with focal signet ring component. No perineural invasion was present. Ancillary tests showed no microsatellite instability.
Magnetic resonance imaging of the liver and CT chest were undertaken to complete staging with no further evidence of metastatic disease shown, giving stage of T4aN0M1aG2‐3 (G histological stage) and an anatomic stage/prognostic group of stage IVB.9
The pathologic subtype remains the dominant factor in survival. The survival rate at 5 years is generally poor among all ACA subtypes. Intestinal or colonic subtype offers the best survival at 52%, mucinous at 44% and the poorest prognosis is seen with signet ring subtype with a survival rate of 20% at 5 years.
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