Case #467 – May, 2018

A 19-year-old female from Northern Manitoba, with no travel history outside of Canada and a significant history of hunting wild animals and exposure to wild canines, recently presented to a local hospital for right upper quadrant (RUQ) pain. She was later transferred to a tertiary care facility after a liver resection procedure for RUQ pain, elevated liver enzymes and white blood cell count, and a few peaks in her absolute eosinophil count; she also had pleural effusion. A 5 cm liver cyst was seen on an ultrasound scan (US) and magnetic resonance imaging (MRI). Cyst fluid was sent to the provincial public health laboratory for analysis. Figures A–C show what was observed on a wet prep with iodine made from the fluid. Figure D is from a smear of the fluid stained with Giemsa; Figure E stained with iron-hematoxylin. What is your diagnosis? Based on what criteria?

(This case and images were kindly provided by the Cadham Provincial Public Health Laboratory, Winnipeg, MB)

Figure A

Figure B

Figure C

Figure D

Figure E

This was a case of echinococcosis. Diagnostic morphologic features shown included:

presence of protoscoleces, which are easily identifiable by the refractile hooklets
presence of refractile hooklets

Echinococcus granulosis occurs practically worldwide and presents as cystic echinococcosis (CE; hydatid disease) with a single, slowly expanding, thick-walled cyst containing daughter cysts. By contrast, E. multilocularis occurs in the northern hemisphere, including central Europe and the northern parts of Europe, Asia, and North America. E. multiocularis presents grossly as alveolar echinococcosis (AE), with many interconnected, thin walled multilocular cysts, rapidly developing and expansively infiltrating the affected organ. Unlike CE, AE is invasive and destructive and may metastasize to other organs of the body and is often fatal if untreated.

Diagnosis of echinococcosis may be undertaken by a combination of medical imaging, serology and PCR. Serological tests specific for E. granulosis will sometimes cross react with E. multilocularis and E. vogeli. In some cases, patients with active echinococcal disease will yield false negative serologic results. PCR of cyst fluid or tissue is recommended to differentiate species, but such testing is surgically invasive and risks cyst rupture in situ, with attendant risk of allergic reaction to fluid leakage and/or cyst dissemination via the released protoscolices. Results from material sent to a reference laboratory in the case presented here indicated E. granulosus infection.

More on echinococcosis: https://www.cdc.gov/dpdx/echinococcosis/index.html

Images presented in the dpdx case studies are from specimens submitted for diagnosis or archiving. On rare occasions, clinical histories given may be partly fictitious.

DPDx is an educational resource designed for health professionals and laboratory scientists. For an overview including prevention, control, and treatment visit www.cdc.gov/parasites/.