Management of serology negative human hepatic hydatidosis (caused by Echinococcus granulosus) in a young woman from Bangladesh in a resource-rich setting: A case report

Abstract

Human cystic echinococcosis (hydatidosis) is a parasitic zoonosis with almost complete worldwide distribution. Echinococcus granulosus, the dog tapeworm, causes hydatidosis which accounts for 95% of human echinococcosis. Although this tapeworm is found in dogs as a definitive host and a number of intermediate hosts, humans are often infected from close contact with infected dogs. Humans are not part of the parasitic lifecycle and serve as accidental hosts. Hydatidosis is an important consideration in the differential diagnosis of hepatic cysts in individuals from endemic areas. Clinicians should be aware of the long incubation period, the high frequency of negative serological tests, and the possibility of intraoperative evaluations of the cyst aspirate being non-diagnostic. We describe a case of serology negative hydatidosis that came to medical attention as an incidental finding in a young woman from Bangladesh. The patient underwent imaging and was then started on albendazole. After several weeks of albendazole, the cyst was punctured, aspirated, injected with hypertonic saline, re-aspirated, and then fully excised. Diagnosis was confirmed by microscopic evaluation of the cyst aspirate. Serological tests for hydatidosis may be negative in patients with early disease and thus should not be used to rule out this disease. Consideration of this diagnosis allows clinicians to avoid the catastrophic spillage of cystic contents risking an anaphylactic reaction, which might prove fatal. Despite World Health Organization hydatidosis staging being based on ultrasound, radiologists in resource-rich setting may prefer MRI in the management and staging of cystic echinococcosis.

Fig. 1

Abdominal computed tomography scan. This is a representative slice from the CT performed during the initial patient hospitalization with the following details. Procedure date: February 23, 2013. Findings: there is a heterogeneous hypoattenuating mass in the liver (8.4 cm × 5 cm × 5.2 cm). Impression: benign versus malignant neoplasm versus hamartoma versus adenoma, less likely hepatocellular carcinoma, no cirrhosis.

Fig. 2

Magnetic resonance scan of upper abdomen with and without contrast. This is a representative slice from the MRI performed during the initial patient hospitalization with the following details. Procedure date: February 24, 2013. Findings: there is a nonenhancing complex cystic lesion in segment 8 of the liver, which contains numerous serpiginous internal septations, small foci of fat and fluid. No additional lesions identified. There is no evidence of intra or extra biliary ductal dilation. The gall bladder is normal. The pancreas, adrenals, and kidneys and spleen are unremarkable. No contrast extravasation into the cyst is seen on the hepatocyte phase images. There is no mesenteric or retroperitoneal lymphadenopathy. The visualized bowel is unremarkable. Impression: cystic liver lesion containing small foci of fat is most likely an echinococcal cyst.

Fig. 3

Appearance, classification of cyst stage, cyst stage description and recommended treatments for echinococcal cysts.