ABSTRACT

Alveolar echinococcosis is an infectious disease caused by Echinococcus multilocularis and it is frequently diagnosed as a space-occupying lesion in the liver. The growth pattern may be similar to that of a malignant tumour with extensive liver infiltration, spreading into neighbouring organs and forming metastasis-like masses in distant organs. Thus, it is one of the differential diagnoses of liver cancer. We report a case that presented as a klatskin tumour clinically and radiologically, but was revealed by pathologic and serologic work-up. Since the courses of these two diseases, a malignancy and an infectious disease, are far beyond comparison, echinococcosis should always be considered in differential diagnosis of obstructive jaundice, especially in the endemic regions.

Keywords: Klatskin tumour, biliary obstruction, alveolar hydatid disease

INTRODUCTION

Echinococcosis is a parasitic infection caused by cestods. Two species have medical importance; Echinococcus granulosus (E. ganulosus) [cause of cystic echinococcosis (CE) a.k.a hydatid cyst disease] and Echinococcus multilocularis (E. multilocularis) (cause of alveolar echinococcosis, a.k.a alveolar hydatid disease). Humans are aberrant intermediate hosts and infected when they swallow eggs in contaminated food (1).

Alveolar echinococcosis (AE) is characterised by an asymptomatic period of five to fifteen years. Under the influence of host’s defence mechanisms, the larva can degenerate and die; residual calcified lesions can be identified incidentally. The process may also show chronic course, and emergence with cholestatic jaundice as the most common symptom. E. multilocularis does not form cysts as E. granulosus does and presents as space occupying lesion in the liver. The growth pattern resembles that of a malignant tumor with infiltration throughout the liver, spreading into neighbouring organs and mass formations in distant organs, mimicking liver cancer. Its diagnosis is based on clinical and imaging findings, histopathology and serology. Whenever possible complete surgical removal of the lesions should be performed (2-4).

In this article, we report a severe AE case, which simulates Klatskin tumor clinically and radiologically. The permission was obtained from the institutional ethics committee (date: 19.7.2019, approval number: 581) for the use of patient data for publication purposes.

CASE REPORT

Seventy four -year-old male patient was admitted because of long-lasting pruritus. Physical examination was unremarkable. His cholestatic enzymes were elevated; gamma-glutamyl transferase: 165 U/L and alkaline phosphatase: 245 U/L. Tumor markers were normal. Mild eosinophilia (%8) was also detected.

Abdominal computed tomography (CT) identified an infiltrative mass, located at the portal hilum, encircling portal vein (PV) and hepatic artery along with infiltration of inferior vena cava. It was constricting PV and obstructing bile ducts (Figure 1a,1b). There was a thrombus formation in the PV and multiple hilar lymphadenopathies. Left liver lob was atrophic, which indicates chronicity. Calcification was not identified. Main radiological differential diagnoses were klatskin tumor and hepatocellular carcinoma. In both cases, the plan was establishment of malignancy to refer the patient for chemotherapy, since the case was unresectable.

Ultrasonography guided fine needle aspiration biopsy was performed with on-site pathology evaluation. Despite the repeated aspirations, material was composed of benign biliary epithelial cells, hepatocytes and inflammatory cells, and suspected malignancy could not be verified. Hereupon, although it was not preferred owing to the close relation of the lesion and vascular structures, the procedure was ended with tru-cut biopsy. After these interventions, the patient had hypotensive and hypertensive attacks, flushing and tachycardia for a while.

Hematoxylin-eosin examination of the biopsy revealed necrosis surrounded by palisading macrophages and dense eosinophil leukocyte infiltration. Concentric eosinophilic structures were identified in necrotic debris (Figure 2), compatible with parasitic infestation. Serologic tests detected immunoglobulin G positivity for E. multilocularis. And the new treatment plan was decided as liver transplantation. He is alive in the fifth year follow-up after transplantation.

DISCUSSION

AE diagnosis might be complicated as in our case (5-7). Stojkovic et al. (6) reported one third of the AE patients had therapy based on a wrong diagnosis, including CE, intrahepatic cholangiocarcinoma and hemangioma.

The difficulty is multifactorial. Firstly, the most common clinical presentation is obstructive jaundice and/or abdominal pain, which has a long list of differential diagnoses. Radiologic pitfalls are another challenging issue. However, the CT scan has a high sensitivity (95%) and hypo-attenuation, calcification, and absence of contrast enhancement in a hepatic lesion usually help identify it as AE, these are not detectable in each case (8). Even histopathology cannot achieve the true diagnosis. And serology may not reliably discriminate the species (E. multilocularis or E. granulosus) which leads to non-curative surgical interventions with the risk of toxic cholangitis if protoscolicidal solutions are applied.

Accurate diagnosis requires multidisciplinary approach especially in complicated cases, as ours (2,9). The distinction of these two prediagnoses cannot be overemphasized, since the management is totally different.

CONCLUSION

When imaging studies revealed a tumor like lesion in the liver, AE should be kept in mind as a possibility in the endemic regions (North America, Alaska, Central Europe, Turkey, Balkan states and parts of Asia) (10). Correct diagnosis requires multidisciplinary approach and being aware of the traps.