Giant filarial retroperitoneal cyst: a diagnostic dilemma

Filarial infections are common in most tropical and subtropical regions of the world. Lymphatic filariasis is caused by either Wuchereria bancrofti, Brugia malayi, or Brugia timori. Extralymphatic filariasis presenting as a primary retroperitoneal mass is very rare despite filariasis being endemic in many regions of India. On review of literature, only a few isolated case reports have been described.We report a case of a huge retroperitoneal cystic mass in a 46-year-old patient who presented with a long-standing, painless progressive abdominal swelling. On examination, there was a large, non-tender, firm swelling of size around 20 × 15 cm occupying the left upper and lower quadrant. The computed tomography of the abdomen was suggestive of thin-walled hypodense cyst of size 25.7 × 15 × 14.3 cm. Laboratory investigations and cyst aspirate were inconclusive for a definite diagnosis. On exploration, a 3-kg cystic mass was removed. The diagnosis of filarial origin was confirmed by the demonstration of microfilaria in the cyst wall and immunochromatographic test (ICT) which was positive.Retroperitoneal lymphatic cyst of filarial origin is very unusual and requires a high index of suspicion if the patient is an inhabitant of an endemic area. The clinical dilemma cannot be resolved with imaging modalities alone, unless a disease-specific manifestation is there. The retroperitoneal cysts often pose a challenge in their diagnosis and management. Small cysts might respond to medical management, whereas large symptomatic cysts will require excision for the final diagnosis and treatment.