Discussion
Tapeworms from the Echinococcus family have been introduced since
the 1950s as a pathogenic parasite for humans. Two important species of
this parasite include E. granulosus and E. multilocularis ,
which cause cystic echinococcosis (CE) and alveolar echinococcosis (AE),
respectively, among which infection with CE is more common. The mature
worm exists in the small intestine of carnivores, and the eggs are
released via the animal’s feces and contaminate water and food. Food
materials contaminated with Echinococcus eggs are swallowed by
intermediate hosts, including herbivores, and the eggs enter the human
body directly (contact with infected animals) or indirectly (eating
contaminated food or water) and the larvae spread through the human body
hematologically and via the lymphatic route (5,6).
This parasite is distributed all over the world, but the endemic areas
include Oceania, China and the central regions of Asia, central and
southern Russia, Middle East, Mediterranean regions, parts of Africa and
North America (6). CE is considered an important parasitic disease in
the world, and is an important concern for developing and low-income
countries due to significant mortality and morbidity. According to the
WHO report, this disease is one of the 17 important neglected parasitic
diseases. More than one million people are infected annually and about
20 thousand people die due to the disease. Disability-adjusted
life-years (DALYs) are estimated to be more than 800,000 years and the
annual treatment cost is over 3 billion dollars (6,7). This disease
usually occurs in the 40s and 50s and is slightly more common in women
than men, and living in urban areas and contact with dogs and livestock
bears a greater chance of infection (3). CE is usually asymptomatic and
is usually found incidentally in unrelated examinations. Although in
many cases, several diagnostic measures are used, CT scan is the gold
standard for hydatid cyst diagnosis (8). Serological tests are only used
to confirm the diagnosis, and negative test results do not rule out CE.
It may take years from the time the parasite enters the human body until
the symptoms develop, and the development of symptoms depends on the
size of the cyst and its anatomical location (9). If symptoms develop,
dull abdominal pain is the most common symptom. Usually, during CE
disease, only one cyst is formed and multi-organ involvement is not
common. The most common site for cyst formation is the liver, followed
by the lungs. Involvement of the CNS, muscles, and spleen rarely occurs,
and involvement of the peritoneum and omentum is extremely rare (3).
The presented patient was an elderly male living in the village with
occasional contact with livestock, who presented with a complaint of
vague abdominal pain and weight loss, as well as a history of colorectal
cancer in the first degree family. Due to iron deficiency anemia and
presence of red flag symptoms, preliminary investigations aimed to rule
out malignancy. Although cystic lesions of the liver and spleen favoring
hydatid disease were found in ultrasound, serology testing of hydatid
cyst was negative. In addition to confirming the presence of a calcified
liver cyst, the CT scan showed an enlarged spleen containing several
cystic structures and evidence of extensive involvement of the omentum
and peritoneum, which looked similar to metastatic lesions and
peritoneal seeding. Therefore, we decided to perform a diagnostic
laparoscopy for this patient, the result of which was the involvement of
the peritoneum and omentum with hydatid disease.
In recent studies, patients with CE mostly had one cyst, and in a study
conducted in 2020 on 501 CE patients over 15 years, the prevalence of
peritoneal involvement was only 1% (3). Study results have shown that
peritoneal hydatid cyst usually occurs secondary to trauma or abdominal
surgery and due to the rupture of a liver cyst in the abdominal cavity.
Despite this, the presented case had no history of abdominal surgery or
blunt trauma to the abdomen. There are various hypotheses regarding the
development of primary hydatid cyst in the peritoneal cavity, none of
which have been proven. Although, it has been suggested that the
localization of hydatid cyst in the peritoneum can be a result of the
migration of the liver cyst through the blood and lymphatic circulation
or the rupture of the adventitia without rupture of the cyst membrane
(4).
The main approaches of treatment are medical treatment with anthelmintic
drugs (usually Albendazole 10 mg/kg), surgery or both. The aim of
treatment is to eliminate the cyst, minimize complications and prevent
recurrence. In this regard, surgery is still the best therapeutic
approach and will convey the best results if combined with medical
treatment. Medical treatment is effective in stopping parasitic growth
and is usually not enough alone. Isolated medical treatment is indicated
when the patient is not a suitable candidate for surgery (10). In the
patient in question, due to splenomegaly and the involvement of all
parts of the spleen, splenectomy was performed, and in relation to the
peritoneal and omental cysts, due to the high risk of perforation
leading to peritonitis and anaphylactic shock, all parts involved with
cysts were removed. Also, due to the calcification of the liver cyst,
this cyst remained intact and the patient was prescribed oral
Albendazole for 3 months.