The initial stage of alveolar echinococcosis is a diagnostic challenge: a case report.

Background: Alveolar echinococcosis is a rare, potentially fatal parasitosis with the main manifestation site in the liver. Diagnosis already in the initial stage of the disease is important to prevent further exacerbation and possible secondary complications by early targeted therapy. Identifying alveolar echinococcosis lesions on imaging can be difficult, and making the diagnosis can be an interdisciplinary challenge, even in a specialized center.

Case Presentation: In a clinically symptom-free 65-year-old white female patient with type 2 diabetes mellitus, an abdominal ultrasonography performed by a colleague in private practice revealed three small hepatic nodules as incidental findings. Further workup focused primarily on the differential diagnosis of hepatic metastatic malignancy. Therefore, a sonographically guided biopsy of the liver lesions was performed under inpatient conditions. During the control sonography routinely performed after the biopsy to exclude postinterventional hemorrhage, an examiner previously uninvolved in the case noticed the typical sonomorphology of initial alveolar echinococcosis lesions in view of the biopsied nodules. The specimens that had been collected peripherally from the target lesion under the primary assumption of metastases histopathologically showed no signs of malignancy and no other landmark findings. Follow-up staining of the biopsies with regard to the recently suspected diagnosis of alveolar echinococcosis, however, remained without a target result as well. Due to the typical sonomorphology, a further biopsy was performed. During rebiopsy, the target lesion was deliberately biopsied centrally to hit the presumed annular lamellar body localized there in alveolar echinococcosis. On the basis of the samples of the second biopsy, the diagnosis of alveolar echinococcosis in the initial stage could be confirmed histopathologically, and the patient was transferred to adequate therapy.

Conclusion: One of the most important differential diagnoses of hepatic alveolar echinococcosis in the initial stage is liver metastases. Knowledge of the typical sonomorphology is essential to avoid misdiagnosis. In addition, proper localization of specimen collection within an alveolar echinococcosis initial lesion is critical to enable histopathologic diagnosis. Imaging and pathology are directly complementary, and imaging can point the way to the correct histopathologic diagnosis on the basis of lesion morphology. For this, knowledge of the specifics of alveolar echinococcosis in imaging and histomorphology is necessary to integratively combine the findings.