Abstract
Although echinococcosis commonly affects liver, unusual sites can also be rarely involved. Lesser sac involvement has been seen with disseminated spread, but isolated hydatid cyst of lesser sac is rare. In this paper we report a case of isolated hydatid cyst in the lesser sac.

Introduction
Echinococcal infection remains an endemic surgical problem in many Mediterranean countries, Australia and South America. Although larval stage of the parasite E granulosis can thrive in many parts of body, majority of the cases does so in the liver followed by lungs, the uncommon sites being peritoneum, spleen, kidneys, bone and brain.¹ But no site is immune.

Case Report
A 20 year old female presented with a painless mass in epigastrium and left hypochondrium since 6 months with no other symptoms. On examination a huge lump measuring 20 cm x 15 cm in size located in the epigastrium and left hypochondrium which moved with respiration, firm in consistency, non-tender with smooth surface. Ultrasound abdomen showed single multiloculated cyst measuring 14 cm x 10 cm in the lesser sac. CT scan abdomen showed a multiloculated cyst measuring 12.3 cm x 10 cm in lesser sac. Spleen and liver appeared normal (Fig. 1).

On exploration with a midline incision spleen and liver were found normal. On opening lesser sac a well defined encapsulated cyst was seen adherent to the hilum of spleen, but free from spleen and pancreas. Removal of cyst with splenectomy was done. The cyst was incised and multiple daughter cysts were identified. Histopathology of spleen was normal confirming that the hydatid cyst was in the lesser sac. Post operative period was uneventful.

Fig. 1 : CT Scan of the upper abdomen showing a multiloculated hydatid cyst in the lesser sac.

Discussion
Echinococcus granulosus disease is prevalent in most parts of the world especially in cattle and sheep farming areas of Asia, North and East Africa, South America, Australia and Middle east. Humans act as intermediate host and become infected through contact with definitive hosts like dogs or other carnivorous animals, or by consuming contaminated water or vegetables.

Most hydatid cysts occur in liver (59-75%) followed by lungs (27%) kidney (3%), bone (1-4%) and brain (1-2%).²

Involvement of the lesser sac though rare is mostly along with disseminated abdominal disease or it may be secondary to peritoneal rupture of type II or type III liver cyst.3 Isolated cysts in the lesser sac form the rarest in the list of unusual sites. Cyst enlarges to cause pain and palpable epigastric mass as presenting symptom. To differentiate from rare primary hydatid disease of pancreas (0.25%) and spleen (< 2%)4,5 contrast enhanced CT scan is the best investigating tool for detailed anatomical resolution and evaluation of type of lesion.6 Exploration and removal of cyst remains the treatment of choice. Hydatid disease may occur any where from big toe to the crown of head.7 High index of suspicion is required for correct diagnosis when it presents in an unusual site or with an atypical radiological appearance

References

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