Giant filarial retroperitoneal cyst: a diagnostic dilemma

BACKGROUND: 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. CASE PRESENTATION: 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. CONCLUSION: 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.