Giant isolated splenic hydatidosis.

Hydatid cyst is endemic in central parts of India, caused by infection with Echinococcus granulosus larva leading to development of cysts. Liver is most commonly involved organ. Isolated splenic hydatidosis is a very rare entity and only small clinical series or case reports have addressed the issue of splenic echinococcosis. We, hereby, present a case of an isolated giant hydatid cyst in spleen of a 30-year-old lady. Splenectomy was done and the diagnosis was confirmed on histopathological examination. Thus, a hydatid cyst should be kept in mind in the differential diagnosis of cystic lesions of spleen.

INTRODUCTION

Hydatid disease is rare in spleen, and its isolated involvement is even more uncommon. It is most commonly seen in the liver (55-70%).[1] Preoperative diagnosis of this infection is mandatory to prevent rupture of the cyst and to avoid anaphylactic shock or local recurrence. To our knowledge, previous descriptions of splenic hydatidosis have been based on imaging findings and lack pathological correlation. We report a case of an isolated giant hydatid cyst of the spleen, suspected on radiology and confirmed on histopathological examination (HPE). This report also impinges on the consideration of hydatid disease as a differential diagnosis in all the patients presenting with a cystic mass in the spleen, in endemic areas.[2]

CASE REPORT

A 30-year-old female patient presented with complaints of fever, breathlessness, dull-aching, continuous pain, and dragging sensation on the left side of the abdomen since 3 months. Also, there was history of loss of weight and appetite. Past history was insignificant. On examination, abdomen was slightly distended with a palpable mass reaching up to the umbilicus, 6-7 cm from the left costal margin. The mass was tender, firm, irregular and fingers could not be insinuated below the ribs. A systemic examination was normal. Routine investigations revealed leucocytosis (Total leukocyte count=12,000/mm3) with eosinophilia (7%, absolute eosinophil count=840/mm3) and raised erythrocyte sedimentation rate (ESR) (35 mm in first hour). An X-ray study of both abdomen and chest was found to be normal. Ultrasonography of the abdomen showed enlarged spleen with multiple cystic areas, together measuring 18×15×11 cm. [Figure 1]. A computed tomography (CT) scan showed a large mass measuring 17.5×15×10 cm, containing air fluid levels and heterogeneous contents with predominant low-density areas, elevating left dome of the diaphragm [Figure 2]. Other abdominal organs were found to be normal. Therefore, the clinical diagnosis of the cystic lesion of spleen was made.

Figure 1

Ultrasound of the abdomen showing splenic hydatid cysts with multiple daughter cysts

Figure 2

CT scan of the abdomen showing a hydatid cyst with primary splenic involvement. The patient had no other organ involvement. Axial contrast-enhanced CT scan through the upper (left) and lower (right) pole of the spleen show a huge cystic mass. Note the peripheral daughter cyst in the superior portion of the mother cyst

Left subcostal exploratory laparotomy was performed revealing huge cystic mass occupying lower pole of spleen. Splenectomy was performed and sent for HPE. Tab. Mebendazole 200 mg/kg/day was started on fifth post operative day and continued after surgery for three months.

Grossly, the splenectomy specimen measured 17×14×10 cm. The posterior aspect showed a cystic cavity having a white and smooth cyst wall, filled with multiple, variable-sized daughter cysts in a flower-shaped arrangement [Figure 3]. The hematoxylin and eosin (H and E)-stained slides showed a cyst wall comprising of three layers [Figure 4]. The cystic contents consisted of mixture of multiple infolded membranes, fragmented hooklets, and debris which were part of hydatid sand. Multiple scolices of Echinococcus granulosus were also seen [Figure 5]. Definitive diagnosis of a hydatid cyst was, hence, made.

Figure 3

Gross photograph of the splenectomy specimen showing multiple daughter cysts giving a flower-shaped appearance

Figure 4

Photomicrograph showing a wall of a hydatid cyst (H and E, ×40)

Figure 5

Photomicrograph showing multiple scolices of Echinococcus granulosus (H and E, ×400)

DISCUSSION

The recorded prevalence of the splenic hydatid cyst is 2.5%,[3] with the highest incidence reported in the central parts of India.[4] It is more commonly seen in sheep and cattle-raising areas of the world.[5] A hydatid cyst is most common in the liver, with lungs being the most probable site of infection in children (15–25% cases). The spleen is rarely involved alone.[4]

It is caused by the larvae of E. granulosus. Humans are the intermediate hosts and contract the infection accidently. Man acts as the end stage of the larval life cycle.[6] The infective eggs, harbored in the small intestine of the definitive hosts like dogs and other canines, ingested from the contaminated food hatch in the gastrointestinal tract and the embryos so liberated in the duodenum, are transported to the liver via portal circulation. It acts as a filter to prevent the further spread of embryos. This is in turn, followed by lungs, which act as second filters.[3] They are mostly seen in children with a latent period of 5 to 20 years. Public health measures and livestock handling procedures have proved to be helpful in decreasing the incidence of hydatid disease.[7] Primary involvement of the spleen is usually seen via arterial route, after having passed through liver and lungs. Retrograde venous spread is also seen in few cases. Secondary disease is mainly caused by the dissemination of the systemic infection or the intraperitoneal spread of the ruptured hydatid cyst of liver.[8]

Hydatid cyst spleen consists of three layers: Outer adventitia formed by the compressed splenic tissue, middle layer of friable ectocyst, and inner germinal layer from where scolices are produced.[8] They are usually asymptomatic but a painful mass in the left upper quadrant of abdomen and splenomegaly may also be seen. Hematological examination may reveal eosinophilia. Abdominal or chest X-rays may show crumpled egg shell-like calcifications in the splenic area. A solitary unilocular lesion or rarely multiple well-defined anechoic spherical cystic lesions with hyperechoic marginal calcification may be seen on ultrasonography. CT may show the cystic lesion with or without the daughter cysts within the spleen with an attenuation value near that of water without any contrast enhancement. Cyst wall calcification is more clearly seen with CT of the abdomen.[8] Magnetic resonance imaging (MRI) is useful in cases of central nervous system involvement.[3] Different serological tests like immunoelectrophoresis, enzyme-linked immunosorbent assay (ELISA), latex agglutination, and indirect haemagglutination test can be used for the diagnosis and screening of hydatidosis and also the follow-up for any recurrence.[8]

Complications include superadded infection, rupture, and fistulization into the bowel, mainly colon. Rupture may also lead to severe anaphylactic reactions, causing fever, pruritis, breathlessness, stridor, and facial edema. Few cases have reported portal hypertension also.[8] Differential diagnosis includes other cystic lesions in the spleen, like pseudocyst, abscess, hematoma, intrapancreatic splenic pseudocyst, and cystic neoplasm and other non-parasitic cysts like dermoid and epidermoid cysts may also cause confusion clinically.[3]

Treatment of hydatidosis includes drugs like albendazole and/or praziquantel. But since medical therapy was not very effective, therefore, splenectomy was traditionally the gold standard for treating hydatid disease of the spleen. Laparoscopic surgery can be advocated in uncomplicated cases.[8] However, recently splenic conservative surgery has emerged as the treatment of choice in suitable cases, and also to reduce the incidence of post-splenectomy opportunistic infections.[6]

CONCLUSION

The incidence of splenic involvement by a hydatid cyst compared to other abdominal viscera is very low. It should always be considered while diagnosing a cystic lesion in spleen.