Introduction:
Dengue fever (DF) is a commonly encountered infectious disease in tropical countries. It can sometimes be complicated by other pathologies, making it challenging to arrive at a diagnosis. In Malaysia, DF has the highest incidence of all infectious diseases. It occurs year-round, and the number of cases reported is currently at an all-time high.

Aim:
This paper aims to highlight our diagnostic dilemma in managing DF with acute perforated appendicitis.

Case study:
A 15-year-old female presented to the Emergency Department after testing serologically positive for DF at a primary care centre. She was discharged home for self-monitoring and recovery. Unfortunately, on the 7th day of illness, she returned with a severe right lower abdominal pain and vomiting. Her blood count showed platelet count of 58 × 103 /μL and a haematocrit level of 32.9%. A subsequent contrast-enhanced computed tomography of the abdomen revealed an inflamed appendix with the presence of a faecolith. An emergent diagnostic laparoscopy confirmed a perforated appendix with faecolith. As the line between the symptoms of DF and acute abdomen blurred, we encountered a diagnostic dilemma that caused a delay in management, resulting in perforated appendicitis.

Results and discussion:
We studied similar incidences in other case reports worldwide. We identified that the most suitable method of differentiating an acute abdomen from other pathologies is by imaging, either via ultrasound or computed tomography studies.

Conclusions:
We established that early clinical suspicion and prompt action are key to recognising an acute abdomen and preventing further complications due to delayed diagnosis.