An unusual case of appendicitis

During my ED days I saw an 8 year old child 2 weeks after an appendicectomy. She had improved immediately after the operation but now returned with ongoing lower abdominal pain similar to what she was experiencing pre-operatively.

My immediate thought was wether this was a surgical complication but there was no fever or vomiting. There were no urinary symptoms and urine dipstick was normal. Her stools were normal and bowels were open daily.

She looked well on examination, was afebrile and had normal vitals. Her abdomen was soft and non-tender. FBC and CRP were also normal.

I was about to call the surgical registrar for advice but then thought I should probably check the histology of the appendix. Firstly we needed to know if the child actually had an appendicitis to begin with. Secondly, could there be some gnarly cause of the appendicitis which hadn't been picked up. I remembered from my Gen Med experience that tumours such as carcinoid could affect the appendix but had never come across this in a child.

I checked the appendix histology. The report confirmed a normal appendix tissue but there was a single Pinworm in the lumen of the appendix !

I treated her with mebendazole and her symptoms resolved.

Nice to see the General Surgeons keeping on top of their histology results !

Learning Nuggets

• Enterobius vermicularis is the most common worm infestation and most commonly affects 5-10 year old children.¹
• Symptoms often include perianal itching, nausea, abdominal pain, diarrhoea.¹
• The caecum and the appendix are the most common sites of infestation.¹
• The clinical picture may mimic acute appendicitis. ¹ This was first noted in 1634.² Pinworms can either obstruct the lumen of the appendix or cause a hypersensitivity reaction.¹ The incidence of pinworms with appendicitis symptoms is 0.2-41.8 %. ¹ Adults can be affected similar to children.
• Only 13-37 % of appendices containing pinworms are inflammed.¹ There is some thought that pinworm infestation could cause an "appendiceal colic" where the patient experiences intermittent or persistent in the right iliac fossa pain due to luminal obstruction.²
• Diagnosis of pinworm infestion in patients with appendicitis symptoms prior to surgery is difficult. Age group, perianal itching and a longer duration of intermittent symptoms should raise suspicion. Ultrasound can apparently spot appediceal lumen infestation.²
• There is evidence to support non-operative management.¹
• There several other causes of appendicitis. Always check the histology.
• Other pathologies which can affect the appendix include: tumours (e.g neuroendocrine, adenoca, mucinous neoplasms, lymphoma), Crohn's, Ulcerative colitis, Vasculitis (e.g PAN, HSP), endometriosis, viral (adenovirus, measles, EBV), Schistosomiasis, Strongyloides, TB, Yersinia, Typhoid, Aspergillosis etc

Further Reading

1. Naalla R, Sankalp, Shetty P, Sud V.Worm in vermiform appendix: a surgeon’s perspective. BMJ Case Rep. 2014;2014:bcr2014205411.
2. Mukherjee D, Naskar PK, Khatua M, Halder P.Pinworm infestation–induced appendicitis in children: a case report and literature review. Res Rev Pediatr. 2022;23(3):84–86.