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WSU Medical School

Training Level

Medical Student


Wayne State University


Introduction: Cystic echinococcosis (CE) is an infection caused by the Echinococcus tapeworm that results in the creation of cysts within a range of visceral organs. Ninety percent of these cysts are in the liver or lungs. In the United States, cases are quite rare and most are found in immigrants from endemic countries. Patients with CE may remain asymptomatic for years. If left undiagnosed and untreated, mortality from CE is estimated to be 90% by ten years. In this case, we discuss a patient who presented to the emergency department with genitourinary complaints and was diagnosed with CE of primary renal involvement, a rare anatomic location.

Case Description: A previously healthy 34-year-old female presented to the emergency department with dysuria, suprapubic pain, myalgias and fever of one day duration. The patient had immigrated from Yemen 6 years prior. On presentation, she was febrile to 38.8C and tachycardic to 133. Complete blood count and lactic acid were within normal limits and urinalysis was not consistent with a urinary tract infection. Ultrasound revealed a mass on the right kidney and computerized tomography (CT) showed a subcapsular right renal cystic mass with septations as well as a secondary liver lesion. Further imaging by magnetic resonance confirmed the subscapular multi-cystic mass along the right kidney measuring 7 x 5.2 x 6.1 cm consistent with CE stage III and a 1.7 cm cystic lesion in the right hepatic lobe also consistent with CE. Serum IgG for echinococcus was positive. The patient was diagnosed with echinococcal disease and was initiated on albendazole 200mg BID for 3-4 months with future plans for surgical intervention.

Discussion: Echinococcal disease is a parasitic infection with the majority of cases originating in the Middle East, South and Central America and sub-Saharan Africa. The clinical presentation of Echinococcus infection is largely dependent on the location and size of the cysts. Small cysts may be asymptomatic whereas larger cysts may cause mass effect or may present with toxic appearance with rupture. Some cysts present with symptoms up to several decades after initial infection or remain asymptomatic indefinitely. The most common sites of involvement are the liver (approximately 66%) followed by the lungs (25%). Less commonly reported sites include the brain, kidneys, muscle, bone and heart. Our patient’s primary renal cyst was large enough to cause mass effect, leading to dysuria and suprapubic pain. Generally, diagnosis of echinococcal disease is made with both imaging and serology. With regards to imaging, ultrasonography is 90-95% sensitive for CE and CT is only moderately better with 95-100% sensitivity; however, CT is superior to ultrasonography for evaluation of extrahepatic cysts. MRI offers no major advantage over CT. When considering serology, antibody detection has greater sensitivity than antigen detection. Our patient tested positive for echinococcal IgG. IgE and IgM were not pursued as IgG has better sensitivity. Management of these cysts are based on the WHO classification criteria and typically use a combination of observation, albendazole, PAIR (percutaneous puncture, aspiration, injection, re-aspiration) and surgery. Our patient’s renal cyst was classified as WHO stage III, for which the recommended treatment is albendazole followed by either PAIR or surgery.

Conclusion: Although CE is uncommon in the United States, careful attention should be paid in individuals who have immigrated from endemic countries. While the liver and lungs are most commonly involved, cysts can be found in any organ and symptoms are often specific to the affected system. The best imaging modality for extrahepatic cysts in particular is by CT. The majority of these patients should be started on albendazole initially with definitive treatment often requiring evaluation by several subspecialists including Infectious Disease, Interventional Radiology and Surgery.

Presentation Date


Renal Cysts in an Immigrant Patient: An Atypical Presentation of Echinococcosis