An unusual presentation of primary splenic hydatid cyst.

The larval form of the parasite Echinococcus granulosus causes a hydatid cyst. The most common sites are liver and lungs. We present an unusual case of an isolated primary hydatid cyst of the spleen. In our case, ultrasonography images of the spleen were not suggestive of hydatid disease except a large cystic lesion. We proceeded to conservative splenectomy that detected hydatid cyst incidentally during operation. This issue is considered common in our geographical area. A high suspicion of this disease is justified in endemic regions. Moreover, medical treatment should precede and follow the surgical intervention.

INTRODUCTION

Hydatid cyst is the larval stage of a dog tapeworm, Echinococcus granulosus. Humans are intermediate hosts and are exposed to the parasite by the fecal-oral and hand-to-mouth route.[1] It can involve any organ of the body but cysts outside the liver and lungs sometimes pose diagnostic dilemmas.[1] Although preoperative imaging modalities, especially abdominal ultrasonography ( USG) and computed tomography (CT) scans are often useful, the exact diagnosis is sometimes made during operation or even during pathologic examination.[2] In this article, a case of an isolated primary splenic hydatid cyst is reported which was diagnosed at operation. The patient underwent cystectomy, and the histopathology report confirmed the diagnosis.

CASE REPORT

A 28-year-old male patient presented to us in the OPD of a rural medical setup of West Bengal, India, with a complain of left upper abdominal swelling with heaviness for the last 1 year and generalized weakness. He was a cultivator from a rural area and had close contact with cattle and dogs.

On examination, the left upper abdomen was found bulged [Figure 1], umbilicus centrally placed, and liver not palpable; the spleen was enlarged 15 cm below the left costal margin, and slightly tender. The rest of the physical examination was normal.

Figure 1

Photograph of the swelling in the left hypochondrium

Routine investigation revealed hemoglobin 11.1 g/dl, total leukocyte count 11.800/mm3, and differential leukocyte count as follows: neutrophil 67%, lymphocyte 23%, eosinophil 8%, macrophage 2%, and basophil 0%. Liver function tests, BUN, creatinine, and blood sugar were normal. X-ray of the abdomen showed a soft tissue shadow without any calcification. Abdominal USG reported an enlarged spleen with a well-defined unilocular cystic lesion without evidence of daughter vesicles. Sonographic and radiographic studies did not show any other cysts in the liver or lungs.

On laparotomy, through an upper midline incision, we found the cystic lesion involving almost whole of the spleen. The aspiration of the cyst showed a clear content. After complete aspiration without any spillage, the cyst wall was incised. A clear, white, definite germinal layer of a hydatid cyst without any daughter cyst was found [Figure 2]. Splenic cystectomy was done. The patient had an uneventful postoperative recovery and was discharged on the eighth post-operative day. The patient was given oral albendazole 400 mg bid for 4 weeks as a prophylactic measure against secondary hydatidosis. He was well at 1 and 2 years of follow-up after surgery. Histopathology of the specimen confirmed a hydatid cyst.

Figure 2

Peroperative photograph showing the spleen and germinal layers of the hydatid cyst

DISCUSSION

Echinococcosis has a worldwide distribution.[1] It has intermediate and definitive hosts. Dogs are definitive hosts and pass eggs in their feces. Cysts develop in intermediate hosts, e.g., sheep, cattle, goats, camels, horses, and humans. On ingestions of beef or lamb, a dog completes the life cycle of the cestode. When human ingests the eggs, embryos escaping from eggs penetrate the intestinal mucosa, enter the portal circulation, and may involve any organ of the body.[1] Approximately two-thirds of hydatid cysts develop in the liver, one-fifth in the lungs, and the remaining in the other organs of the body. The cyst grows at a rate of about 1 cm a year.[2] Many primary splenic cysts were reported in the literature but the presentation of our case was unusual.

The primary infestation of the spleen usually takes place by the arterial route by passing the liver and lungs. A retrograde venous route is also reported.[2] Secondary splenic hydatid disease usually follows systemic disseminated or intraperitoneal spread following a ruptured hepatic hydatid cyst.[2]

Splenic hydatid cysts are usually asymptomatic but may present as a painful mass in the left upper abdomen. Its complications are mainly due to compression, infection, intra-abdominal rupture, anaphylaxis and secondary hydatidosis,[3] fistulization to colon,[2] and rupture into the thorax; portal hypertension has also been reported to be a cause.[3] Slow leakage of the hydatid fluid from the cyst elicits eosinophilia.

The main differential diagnoses of splenic hydatidosis are any splenic cystic lesions such as pseudocyst, abscess, hematoma, and cystic neoplasm.[34]

The laboratory evaluation of patients with hydatid disease often yields nonspecific data, being eosi-nophilia (above 3%) reported to be present in only 25% of cases.[4] Elevated IgE levels are a nonspecific indicator of prior sensitization, while an elevated echinococcal IgM antibody level may be a sensitive indicator of active infection with parasites. Immunoelectrophoresis, ELISA, and IHA test are the different serological tests for diagnosis, screening, and follow-up for recurrence.[4]

Marginal or crumpled egg shell-like calcifications in the splenic area on the abdominal or chest radiograph are suggestive of splenic hydatidosis.[5] Sonography may reveal a solitary unilocular lesion or rarely multiple well-defined anechoic spherical cystic lesions with hyperechoic marginal calcification in the spleen. CT may show the cystic lesion with or without the daughter cysts with an attenuation value near that of water without any contrast enhancement. USG is cost effective and valuable for follow-up screening but CT is more accurate in localizing and delineating the extent and wall calcification of the cyst.[5]

Although preoperative diagnosis is usually possible with imaging modalities like ultrasound, CT, and with serological testing, some cysts may only be diagnosed intraoperatively.[4]

Benzimidazole compounds (mebendazole and albendazole) are antihelminthic drugs that kill the parasite by impairing its glucose uptake. Albendazole is the drug of choice because of its better absorption and better clinical results in comparison with mebendazole.[6] It is indicated in inoperable cases. However, pre- and postoperative 1-month courses of albendazole should be considered in order to sterilize the cyst, to decrease the chance of anaphylaxis, to decrease the tension in the cyst wall (thus reducing the risk of spillage during surgery), and to reduce the recurrence rate postoperatively.

Open splenectomy has been the traditional treatment of choice for splenic hydatid cysts for decades as it was simple and safe even in 2002 as reported by Dar et al.[7] but in 1980, spleen-sparing methods were proposed especially for children to prevent immunological consequences and postoperative sepsis. A laparoscopic approach has also been advocated for uncomplicated hydatid cysts of the spleen.[3]

A hydatid cyst should be borne in mind in the differential diagnosis of any splenic cyst, especially in endemic and rural areas. Conservative surgery with a laparoscopic approach has become popular in recent years in suitable cases. Moreover, medical treatment should precede and follow the surgical intervention.