Lymphatic filariasis remained silent until presentation with huge abdominal mass mimicking malignancy: a case report.

Background: Lymphatic filariasis (LF) is an endemic infection seen in the tropical and subtropical regions of the world, including Nepal. It is a mosquito-borne neglected tropical disease and is caused by a nematode parasite. Case Summary: We reported an unusual case of LF in a 50-year-old male who presented to a tertiary hospital in Kathmandu with a complaint of a palpable abdominal mass mimicking malignancy. A CT scan revealed a large mesenteric cystic mass measuring approximately 23 × 15 cm. These findings initially directed the clinicians toward a diagnosis of malignancy, leading to blood tests for cancer markers, for example, carcinoembryonic antigen, which showed slight elevation supportive of this suspicion. Given the cystic nature of the mass and intestinal obstruction, surgical intervention was performed to place a pigtail catheter for drainage, and a fluid sample was sent for cytopathological evaluation for malignancy as well as biochemical and microbiological evaluation. Initially, biochemical and microbiological findings were reported as normal. Cytopathological study on stained slides (Giemsa and Papanicolaou) revealed multiple threadlike microfilaria larvae, the morphology of which resembled Conclusion: LF may remain asymptomatic for decades. This case highlights that LF may present with an abdominal mass mimicking malignancy.