Summary: Presently Dengue appears with its varied features of presentation and progression. We report a case of acalculus cholecystitis in DHF from department of medicine, Combined Military Hospital, Dhaka. The patient presented with fever and diarrhea later developing abdominal pain. Her platelet counts were low and Dengue antibody test (Ig M) was positive with altered liver enzymes. Ultrasound showed thick walled gall bladder with clear lumen without stone or sluge, a feature of acute acalculous cholecystitis. The patient was successfully managed conservatively. Key words and abbreviations: Dengue hemorrhagic fever, Combined military hospital, Acute acalculous cholecystitis. (J Bangladesh Coll Phys Surg 2017; 35: 155-157) Journal of Bangladesh College of Physicians and Surgeons Vol. 35, No. 3, July 2017 Acute Acalculus Cholecystitis in Dengue Hemorrhagic Fever-A Case Report MAA MIA, M MOSTAFI, S PERVEEN, NG CHOWDHURY, M A AHMED, SMM RAHMAN Introduction: Dengue Fever (DF) is caused by single stranded RNA flavivirus that is transmitted by the bite of female Aedes aegypti mosquito. 1 Dengue fever is usually a non- specific and self-limiting biphasic febrile illness but the presentation may range from asymptomatic to Dengue fever, Dengue hemorrhagic fever, Dengue shock syndrome and recently, Expanded dengue syndrome or Isolated organopathy with unusual manifestations. Typical Dengue fever is characterized by high-grade fever, musculoskeletal pain, retrobulbar pain, headache, joint pain, nausea, vomiting and morbilliform rash. Fever, headache and abdominal pain are common manifestations. 2,3 Atypical presentations like DF complicated by acute acalculous cholecystitis are rare. 4 Acute acalculous cholecystitis has been described in the course of various diseases and conditions. Occasionally rapid progression to gangrene and gallbladder wall perforation occurs. Therefore, prompt surgical intervention are warranted. Acalculous cholecystitis in the course of dengue is usually a self-limiting disease and surgery if undertaken without proper diagnosis then chances of complication rise as it may be associated with thrombocytopenia, shock and hemorrhage. In these cases, a high clinical suspicion is required to make an early diagnosis and initiate prompt treatment. If unrecognized, the delay in treatment may lead to serious complications. This report describes an unusual manifestation of Dengue fever developing acute acalculous cholecystitis. Case Report: A 38 year old female presented with fever and diarrhea with headache, bodyache and severe weakness for 10 days followed by acute onset of abdominal pain and vomiting for 2 days. She was non-diabetic and non- hypertensive but suffering from hypothyroidism for 10 years and getting 50 micrograms of thyroxine daily. On physical examination, she was pale and ill. Her temperature was 39.5 o celcius, pulse 100/minute and blood pressure 100/60 mm Hg.There was no jaundice or rash on general examination. Abdominal examination revealed diffuse tenderness. Laboratory findings showed hemoglobin level of 10.4 g/dl with hematocrit of 32%, TLC was 4.5x10 9 /l with 87% neutrophils and 10% lymphocytes. Platelet count was 70x10 9 /l. Peripheral film showed pancytopenia. Dengue IgM antibodies came out positive. Malarial Parasite was negative and blood culture showed no growth. A clinical diagnosis of Dengue fever with diarrhoea was made. She was admitted and given a standard diet. The patients condition deteriorated progressively with continued fever, vomiting, increasing abdominal pain and diarrhea with greenish stool in spite of multiple broad spectrum antibiotics. Abdominal tenderness was more marked in right hypochondrium associated with positive Murphys sign. The ultrasound examination of upper abdomen showed thick walled gallbladder measuring 9 mm without calculi, mass or sludge in the lumen suggestive of acute acalculous cholecystitis. There was minimal Maj Gen Md Abdul Ali Mia, Brig Gen Mamun Mostafi, Col Shaila Perveen, Col Niamul Gani Chowdhury, Col Mir Azimuddin Ahmed, Lt Col SM Mizanur Rahman Address for Correspondence: Colonel Shaila Perveen, Classified Medicine spl & Head of Gastroenterology, CMH, Dhaka. Mob:01819294922 Received: 27 Dec. 2016 Accepted: 8 June 2017