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 Table of Contents  
ORIGINAL ARTICLE
Year : 2021  |  Volume : 16  |  Issue : 1  |  Page : 86-89

Prevalence of hepatic alveolar hydatid in a nonendemic region of North India in hospital-based population: Emerging trend or improved diagnostic workup


1 Department of General Surgery, SKIMS Medical College Bemina, Srinagar, Jammu and Kashmir, India
2 Department of Radiodiagnosis, Sher-i-Kashmir Institute of Medical Sciences, Srinagar, Jammu and Kashmir, India

Date of Submission21-May-2019
Date of Decision15-Jan-2020
Date of Acceptance04-Feb-2020
Date of Web Publication29-Jul-2021

Correspondence Address:
Dr. Mohd Ilyas
Department of Radiodiagnosis, Sher-i-Kashmir Institute of Medical Sciences, Srinagar, Jammu and Kashmir
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/jdmimsu.jdmimsu_86_19

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  Abstract 


Objective: The objective of this study was to calculate the prevalence of hepatic alveolar hydatid disease in hospital-based population in North India, a nonendemic region for alveolar hydatid disease. Materials and Methods: This study was conducted at a tertiary care center in North India between April 2017 and March 2019. Patients with suspected hepatic alveolar hydatid on ultrasonography were evaluated with further imaging studies based on classical radiological findings and then confirmed by histopathology. Results: Twenty-five cases of hepatic alveolar hydatid were diagnosed primarily based on the classical imaging/radiological findings with histopathology confirmation, with a 2-year period prevalence of 0.207 cases/1000 population. Majority of the cases were in the age group of 41–60 years, with a mean age of 53.04 years. Fifty-two percent of the cases were female. Majority of them were from hilly areas and working with livestock animals. Abdominal pain was the most common presenting symptom. Conclusion: Hepatic alveolar hydatid is considered as a rare disease in India; however, the increased number of cases been diagnosed in our study could be either due to increased diagnostic modalities or due to actual increase in the number of cases. Therefore, hepatic alveolar hydatid should be considered in the differentials of suspicious liver mass in nonendemic regions.

Keywords: Echinococcus multilocularis, hepatic alveolar hydatid, malignancy


How to cite this article:
Ahmad I, Ilyas M, Ashraf A, Rather AA, Gojwari TA. Prevalence of hepatic alveolar hydatid in a nonendemic region of North India in hospital-based population: Emerging trend or improved diagnostic workup. J Datta Meghe Inst Med Sci Univ 2021;16:86-9

How to cite this URL:
Ahmad I, Ilyas M, Ashraf A, Rather AA, Gojwari TA. Prevalence of hepatic alveolar hydatid in a nonendemic region of North India in hospital-based population: Emerging trend or improved diagnostic workup. J Datta Meghe Inst Med Sci Univ [serial online] 2021 [cited 2021 Sep 23];16:86-9. Available from: http://www.journaldmims.com/text.asp?2021/16/1/86/322643




  Introduction Top


Hepatic alveolar hydatid, also called hepatic echinococcosis, is caused by the larval stage of Echinococcus multilocularis.[1],[2],[3],[4],[5] The disease is confined to the northern hemisphere with China accounting for 91% of cases.[1] The adult forms of E. multilocularis live in the intestines of fox.[6],[7],[8] Humans are accidental intermediate hosts.[1],[6],[7],[8] After the ingestion of the eggs by humans, the larvae travel to the liver (first and most common organ involved) where they create alveolar-like structure and alveolar cysts.[1],[6],[7],[8] Presentation is variable due to slow growth of the disease process ranging from asymptomatic cases in early stages to complications in late stages.[1]

There have been case reports from India regarding alveolar hydatid disease, and no study has been conducted to assess the prevalence of this disease. This study was conducted on hospital-based population in Kashmir region of North India to calculate the prevalence of the disease in hospital-based population.


  Materials and Methods Top


This was an observational study conducted at a tertiary care center in North India. The study was conducted between April 2017 and March 2019 on patients who were referred for ultrasonography (USG) either as part of routine basic investigation for nonspecific complaints/incidental finding or as part of evaluation for symptomatic cases. Patients with suspected alveolar hepatic hydatid disease on USG were thoroughly evaluated and subjected to computed tomography (CT), magnetic resonance imaging (MRI), and histopathology. We calculated the prevalence of hepatic alveolar hydatid cases based on classical imaging criteria with confirmation on histopathology. Only cases with classical radiological findings with confirmation on histopathology were included in the study. Cases in which histological findings or further evaluation suggested/confirmed alternative diagnosis were excluded from the study. The data were then compiled and the results were obtained.

Ethics statement

Ethical approval was not applicable to this study as the study did not involve animal/human subjects for any drug trial/ intervention; however, the study was duly approved by the Institutional Review Board of our institute (IRB SKIMS).

Informed written consent of patients or the guardian was obtained wherever applicable.


  Results Top


A total of 120,620 ultrasound studies were done in a 2-year period. All cases of liver masses underwent further imaging and histopathological studies. A total of 25 cases of hepatic alveolar hydatid were diagnosed primarily based on the classical imaging/radiological findings with histopathological confirmation, with a mean age of 53.04 years with the oldest patient aged 73 years [Table 1]. One case of metastatic alveolar hydatid was seen with multiple lesions in both lungs besides liver lesions. The 2-year period prevalence of the hepatic alveolar hydatid in our study was 0.207 cases/1000 population. Thirteen out of 25 (52%) cases were female and 12 were male. Occupationally, 7 out of 25 were nomadic shepherds and 18 were those working with other livestock animals and forests. Twenty-one were from hilly areas with neighboring forests and four were from semi-urban areas. Sixty-four percent (16/25) of the patients presented with either abdominal pain or mild abdominal discomfort. Five patients were detected incidentally on USG for unrelated symptoms, and four patients presented with jaundice. [Figure 1], [Figure 2], [Figure 3], [Figure 4] show classic appearances of alveolar hydatid on various modalities in different patients.
Table 1: Age-wise distribution of the patients

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Figure 1: Ultrasonography image showing a large hyperechoic mass in the right hepatic lobe with central calcifications and peripheral small cysts

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Figure 2: Computed tomography image showing two hypodense masses with coarse calcifications in the right and left hepatic lobes. The masses did not show any enhancement on contrast study

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Figure 3: T2 HASTE fat-saturated thick multiplanar reformation image showing a large microcystic parasitic mass which involves the right lobe of the liver and was seen invading the porta hepatis

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Figure 4: Histological images showing the classic images of microvesicular appearance of alveolar hydatid

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  Discussion Top


Hepatic alveolar hydatid, also called hepatic echinococcosis, is caused by the larval stage of E. multilocularis.[1],[2],[3],[4],[5] Alveolar hydatid disease is confined to the northern hemisphere, i.e., China, Europe, Russia, Japan, and North America. The total number of alveolar Echinococcus cases in the world is 18,235 per year with China accounting for 91% of cases.[1] Most human cases have been reported in endemic areas of Western and Central Europe, including Turkey, the former Soviet Union, Iran, Iraq, Western and Central China, and Northern Japan (Hokkaido Island)[9],[10] with an incidence of 170–200 cases/year in Western and Central Europe.[11] The adult forms of E. multilocularis live in the intestines of definitive hosts, which mainly include fox and wolves, and the less common ones include domestic dogs and cats. The eggs are released in the stools of the definitive hosts, which are ingested by the intermediate hosts.[6],[7],[8] Humans are accidental intermediate hosts.[1],[6],[7],[8] Ingestion of the eggs by humans usually occurs because of the contamination of food by the feces of definitive hosts. After the ingestion of the eggs by humans, the larvae travel to the liver, where they create alveolar-like structure and alveolar cysts.[1],[6],[7],[8] The liver is the first and most common organ to be affected by larval infestation.[7] Human alveolar hydatid disease is a severe and emerging disease which can be life-threatening if diagnosis is delayed.[1]

The presentation of hepatic alveolar hydatid disease is variable. Patients become symptomatic in the later stages of the disease due to slow growth. Some patients present with mass lesions in the liver, abscess, and jaundice, and life-threatening complications such as cholangitis, biliary cirrhosis, and portal hypertension. The cysts have a tendency to recur. The release of metacestode vesicles into the blood or lymphatic vessels may lead to metastases to lungs, brain and bones, etc.[1] The characteristic feature of alveolar echinococcosis is a tumor-like pattern of growth.[7] Radiological investigations such as USG, CT, and MRI with standard and diffusion-weighted images are complementary to each other for diagnosis. USG is the preferred investigation for the screening of hepatic alveolar hydatid.[12],[13],[14] On ultrasound, alveolar hydatid manifests as a large space-occupying lesion with alternating areas of mixed echogenicity with irregular margins[3],[7] with scattered foci of calcification. It also may show multiple hyperechoic nodules giving a “hailstorm” appearance.[7] CT scan has the capacity to determine the extension of the disease, size, number, and localization and allows preoperative evaluation of biliary and extrahepatic extension, which is an important consideration for assessing resectability of the lesion.[15],[16] MRI is the best modality for characterizing the components of parasitic lesions and depicting vascular or biliary tree involvement and extrahepatic extension.[3] On MRI, the liver mass of alveolar hydatid presents as an irregular, solid-cystic mass, with honeycomb appearance in T2-weighted images.[17]

The gold standard for the diagnosis of hepatic alveolar hydatid is a tissue diagnosis. On histopathology, the most common finding is extensive necrosis, with small vesicles and delicate membranes scattered in the necrosis, but the most common pitfall for the pathologist is missing the above-mentioned structures and calling the biopsy unsatisfactory because of extensive necrosis.[18],[19]

Although India is located in the northern hemisphere, there are only case reports of alveolar hydatid disease from India,[20],[21],[22] and incidence in India as calculated based on the case reports is 1 per year.[23] There have been no studies regarding the disease burden from India. Climatic and landscape conditions (areas with very cold winters and high annual rainfall levels) have been demonstrated to increase the risk of developing alveolar hydatid among humans. The mountain climate communes in France have displayed a 133-fold increase in alveolar hydatid risk compared with communes in which the majority of the population resides.[24] The characteristic tumor-like pattern of alveolar hydatid on imaging studies[7] can be misleading at times to label it as malignancy. Another important aspect of diagnosis of alveolar hydatid is the familiarity of radiologists with hepatic alveolar hydatid imaging findings[17] which can be more important in nonendemic areas due to sparsity of cases. Kashmir is a region having cold winters with sufficient rainfall. Majority of the population of Kashmir is residing in rural areas (72.62%).[25]

On reviewing the data of the same hospital, only one case has been reported from the same hospital before 2017 which was misdiagnosed as cholangiocarcinoma on radiology and turned out to be alveolar hydatid on operative and postoperative findings. One of the reasons for such an increase in cases could be the familiarity of radiologists with imaging findings of alveolar hydatid. This study could possibly explain that alveolar hydatid disease might be uncommon but not so rare in North India, and the increased number of cases been diagnosed in this study could be either due to increased diagnostic modalities/familiarity of radiologists with imaging findings or due to actual increase in the number of cases. Therefore, alveolar hydatid disease should be considered in the differentials of suspicious liver mass in nonendemic regions as well.


  Conclusion Top


Despite geographical location of India in Northern Hemisphere, alveolar hydatid disease which is confined to Northern Hemisphere is considered as a rare disease in India; however, the increased number of cases been diagnosed in our study could be either due to increased diagnostic modalities or due to actual increase in the number of cases. Therefore, hepatic alveolar hydatid should be considered in the differentials of suspicious liver mass in nonendemic regions.

Limitations of the study

As this study was conducted on hospital-based population from Kashmir region of North India, there is a possibility that the figures in this study might not represent the actual disease burden in the general population which needs thorough epidemiological studies to calculate the exact prevalence of the disease.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

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Nunnari G, Pinzone MR, Gruttadauria S, Celesia BM, Madeddu G, Malaguarnera G, et al. Hepatic echinococcosis: Clinical and therapeutic aspects. World J Gastroenterol 2012;18:1448-58.  Back to cited text no. 1
    
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    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4]
 
 
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