Echinococcal lump: An unusual differential diagnosis for a right iliac fossa lump

To report the rare case of a primary peritoneal hydatid cyst in a 65-year-old lady. A 65-year-old female presented with a 3-month history of a painless progressive swelling in the right lower abdomen. The lump was 10 cm × 8 cm in size, non-tender, cystic in consistency, and was located in the right iliac fossa and part of the right lumbar region; mobility was restricted in all directions. CECT showed a large septated cystic lesion 14 × 9 × 8 cm in size with enhancement, and sharp regular outline in the right lower abdomen along the anterior aspect of the right psoas muscle. The liver and spleen were not affected. During surgery, a cystic swelling was exposed. Aspiration revealed a clear fluid with some floating material. The cyst wall was incised and fluid along with daughter cysts were removed keeping the pericyst in situ. Histopathological examination confirmed hydatid disease. Primary peritoneal hydatid cysts, though very rare, should be kept in mind in the differential diagnosis of a right iliac fossa lump in areas where hydatid disease is endemic.