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A recent hospital discharge letter gave a diagnosis of a patient who had been admitted with possible acute appendicitis as low-grade appendiceal mucinous neoplasm (LAMN). What is LAMN?

LAMN is an uncommon tumour of the appendix that is usually diagnosed incidentally after surgery.

LAMN occurs in approximately 1% of patients undergoing appendectomy. It is characterised by low-grade cytologic features, an invasion pattern of the appendiceal layers, a villous or flat proliferative intestinal-type mucinous epithelium, significant mucin production, and typical limitations of the muscularis propria.

Although LAMN may be asymptomatic, it can rupture and seed mucin and neoplastic epithelium into the peritoneum, causing pseudomyxoma peritonei. This is a complication of mucinous LAMN that develops from peritoneal seeding in around 20% of patients with a mucinous adenoma.

Patients with LAMN often show appendicitis-like symptoms, such as pain in the right iliac fossa, fever, nausea and vomiting.

Depending on the increase in mucin in the appendix lumen, LAMN may present as a palpable mass or may be diagnosed after appendectomies are performed owing to appendiceal abnormalities in surgeries performed for other reasons. In more advanced stages, patients can present with intermittent colicky pain, intestinal obstruction due to mass effects, and genitourinary symptoms due to obstruction of the ureter.

Finally, elevated levels of cancer embryonic antigen, cancer antigen 19-9 and cancer antigen 125 are detectable in the majority of patients with LAMN.

For more information, see Primary Care Notebook.

Other highlights in this month’s email include an update of the bird flu section and new information on cytisinicline and smoking cessation, dapagliflozin plus calorie restriction for remission of type 2 diabetes and dietary fibre in irritable bowel syndrome.

• Dietary fibre in irritable bowel syndrome (IBS): What is psyllium? Does this substance worsen or improve symptoms in IBS? Is soluble or insoluble fibre recommended in the management of IBS?
• Dapagliflozin plus calorie restriction for remission of type 2 diabetes: Does the evidence show that dapagliflozin can be used in achieving type 2 diabetes remission?
• Cytisinicline and smoking cessation: A review of this new option in the management of smoking cessation is provided.
• Bird flu section: Bird flu is caused by the highly pathogenic avian influenza H5N1 virus, which is panzootic in poultry and can infect humans. The section has been updated on Primary Care Notebook.
• Low-grade appendiceal mucinous neoplasm: This condition is summarised on Primary Care Notebook.
• GLP-1 and dual GIP/GLP-1 receptor agonists – potential risk of pulmonary aspiration during general anaesthesia or deep sedation: It has been noted that underlying diabetic gastroparesis, as well as other comorbidities such as obesity or gastro-oesophageal reflux disease, and symptoms of delayed gastric emptying (including nausea, vomiting and abdominal pain), may be associated with a higher risk of pulmonary aspiration.