Isolated Giant Primary Splenic Hydatid Cyst in a 10-Year-Old Boy: A Case Report

Plain Language Summary

Hydatid disease, a geographically widespread zoonosis, is commonly seen in most sheep-raising countries in Asia, Africa, and other parts of the world. There are two types of parasites mainly involved in this disease, Cestodea (flatworms, tapeworms) and nematode (roundworms). The global incidence of primary splenic hydatidosis is rare. It occurs between 0.5% and 6% of patients and can be manifested both isolated or in concurrence with other hydatid diseases. We describe this case of a giant primary splenic HC in a ten-year-old boy who was brought to the clinic with complaints of pain and non-tender swelling in the left hypochondrium. Abdominal US and CT scan were performed to establish the diagnosis of a large splenic HC. There was no manifestation of any other organ or system involvement. The patient underwent a total splenectomy, and pathological examinations confirmed the cystic hydatidosis diagnosis. In conclusion, total splenectomy is the best choice for gaint HC to avoid complications and recurrence.

Introduction

Hydatid disease is a serious zoonotic disease and a substantial health risk in endemic areas. The larval stage of Echinococcus tapeworm causes the infection. Dogs are the primary host of this worm, and the intermediate hosts are sheep and cattle.¹ Human acts as accidental intermediate hosts in the dog-sheep life cycle of this parasite. Hydatidosis can involve organs such as the liver (60–70%), lungs (20%) and infrequently in the thyroid, pancreas, kidneys, bone, breast, and spleen.² While secondary splenic involvement is the third most common organ involvement, primary splenic HC has a rare incidence (0.5–6%).³

Berlot was first to introduce Primary splenic hydatidosis in 1790.⁴ Primary splenic infestation usually occurs when the parasite passes through the arterial route of two filters, hepatic and pulmonary. There were also reports of the retrograde venous route, which bypasses the arteria route.¹ The primary manifestation of splenic hydatid disease is slowly growing asymptomatic cystic mass but might also present as painful bulging in the left hypochondrium. The patient may also present with dyspnea, anaphylactic responses caused by rupture of the cysts.⁵ The unusual location of HC may mislead physicians in differential diagnosis.^4,6 HC may present as a solitary or multiple cysts which each cyst can be multiloculated. US can reveal some specific signs such as daughter cyst, membrane detachment, and cyst wall calcification. Splenic HC presents itself as marginal or wrinkled eggshell like calcifications on x-rays.⁶

Farrokh and Singal were report primary splenic HC in children. Although splenic HC is a rare phenomenon, the authors suggest considering this diagnosis in spleen cystic lesion cases, especially in endemic areas.^7,8 In this study, we report a large primary splenic HC in a ten-year-old boy, rarely reported during childhood.

Case Report

The ethics committee of Ibb University of Medical Sciences approved this study. A ten-year-old boy came to our general surgery outpatient department of Al-Thora hospital, Ibb, Yemen, with a bulging in the left hypochondriac region. His father mentioned that the mass had started to overgrow over the last nine months. We took the family history and found that he lived in a village and owned a dog, which he keeps in the house, and he had no history of pica. On physical examination, the mass was occupying the left upper quadrant extending up to the umbilicus. The mass had limited horizontal mobility but moved with respiration. He had no other abdominal complaints. White blood cell was 2910 cell/mm³, hemoglobin was 11.7 g/dl, and mild eosinophilia (7%). Liver and kidney function test results were normal. The abdominopelvic US showed a 20 cm spleen cystic mass with several vasculatures compressing the left kidney.

In the left hypochondrium, xray showed a well-defined, rounded soft tissue opacity with some marginal calcification. The chest X-ray was normal. A large solitary 20×16×18cm cystic mass in the spleen’s hilum was detected in the abdominal ct-scan. It was sharply marginated and contained multiple round calcified peripheral daughter cysts (Figure 1). No other cystic lesion was detected in other organs such as the liver and peritoneum. Echinococcus latex hemagglutination test and indirect hemagglutination test were reported 1:6000 and 1:2200, respectively, which was positive. We made the diagnosis of a splenic HC based on imaging reports and hemagglutinations test results.

Figure 1 Axial (A) and sagittal (B) view of abdominal CT scan showing a calcified wall splenic hydatid cyst (arrow).

To perform laparotomy, via a midline incision, the abdominal cavity was explored, which revealed a large splenic cystic mass. The mass had adhesions to the diaphragm and displaced the left kidney and left adrenal posteriorly. The mass also pressurized the pancreas towards the right side and the stomach and the liver’s left lobe anteriorly. The splenic hydatid cyst’s fluid content was aspirated, and then 20% hypertonic saline was injected. After re-aspiration, we opened the cyst cavity and removed all endocysts. After this, we performed a splenectomy with the cyst (Figure 2). Using hypertonic saline (NaCl 20%) abdominal cavity was washed to prevent any potential contamination induced infection. No blood transfusion was needed during surgery. Histopathological report described a laminated cyst with many scolices with a double layer of hooklets, a classic report of Echinococcus granulosus infection (Figure 3). The patient has a normal postoperative course in the hospital and was discharged on the 5th day on albendazole (6 mg/kg every twelve hours for three weeks).⁴ The patient also received prophylactic vaccination against Haemophilus influenza type b, Streptococcus pneumonia, and Neisseria meningitides one week after surgery. Abdominal CT scan follow-up at the sixth month after the surgery demonstrated the absence of recurrence.

Figure 2 (A) Hydatid cyst within splenectomy specimen (arrow). (B) Hydatid cyst after removal.

Figure 3 Histopathological specimen confirmed the hydatid cysts. The fibrous layer was named directly. Arrows showed shreds of the intermediate lamellar chitinous layer and the scolices in the inner layer.

Discussion

HC is a comonly found disease in farming communities, including the Middle East countries and the Republic of Yemen.⁹ Even in endemic areas, spleen HC is a rare phenomenon. Since the liver and lung act as first and second effective filters for most larvae, only 15% of cyst embryos can enter the systemic circulation to settle in other organs such as the spleen, mostly through arterial routes. For cyst embryos, another route to bypass the lung and liver is the portal and splenic veins.²

Primary splenic involvement is rare, but secondary involvement is common after the systemic dissemination via vessels or HC’s local dissemination in the ruptured cyst.³ In the pediatric population, the most involved organ is the lung.⁵

Physicians can easily get confused and neglect HC diagnosis when presented in an unusual organ. Pseudocyst, hematoma, abscess, and cystic neoplasms are considered as the primary differential diagnosis of splenic hydatidosis. Different types of splenic cystic lesions such as Splenic HC are mostly asymptomatic.¹⁰

Similarity in presentation and radiologic findings often makes preoperative diagnosis difficult. In 90% of cases using serological tests like ELISA, indirect hemagglutination test, and immunoelectrophoresis added with imaging findings can lead to successful splenic hydatidosis diagnosis.¹¹

Our patient was admitted to the inpatient department due to pain and a rapidly enlarging mass in the abdomen left upper quadrant area. Abdominal US and CT scan findings in the patient showed cyst wall calcification, daughter cysts, and membrane detachment, which is characteristic of HC findings.¹² The size of isolated giant splenic HC was more than 20 cm in previous articles such as Pukar et al and Sarkari et al, which were similar to our report.^4,12 Parasite-Human Immunologic relationships and the enveloping defensive structure around cysts are the main contributors to the growth of a HC.

Main surgical approaches to splenic hydatid disease are partial splenectomy, total splenectomy, cyst enucleation, removal with laparoscopy, and unroofing with omentoplasty.^4,13 However, the standard management of giant HC is total or partial splenectomy for avoiding spontaneous or traumatic rupture.⁵ Partial splenectomy had an increased risk of bleeding when incising the splenic tissue, and unroofing the cyst wall had a risk of severe postoperative infection due to the residual space. Therefore, in case of multiple splenic cysts, total splenectomy is advised, especially when there are adhesions between the spleen and nearby organs.¹⁴

Due to the giant cyst size and its adhesion to surrounding tissues, we decide to drain the cyst. Before opening the cavities, aspiration of cyst fluid was done, and to kill daughter cysts, we inject and re-aspirated hypertonic saline 20% as a chemotherapy agent.^5,6 Albendazole was administered as the main therapy is the postoperative and follow-up period.⁶

Conclusions

Primary splenic HC is rare. It presents mostly with a vague painful abdominal mass. US of the abdomen and CT scan are helpful to make the diagnosis. The approach and management must be individualized for each patient. In our patient, total splenectomy was the best choice to avoid complications and recurrence.