Liver Damage in Pediatric Chronic HCV Infection
Data are derived from vertically infected children identified in prospective studies and series of children who were found to have HCV chronic infection at varying times of life, when screened because of risk exposures or asymptomatic aminotransferase elevation. Provided the children are otherwise healthy and not affected by chronic illnesses, the characteristics of chronic HCV infection are not related to the mode of infection acquisition (parenteral or vertical route).
Chronic HCV infection is usually an asymptomatic disease. Nearly 15% of children present nonspecific, mild and transient symptoms at the time of initial diagnosis, probably related to intercurrent illness that leads to HCV detection. Hepatomegaly is noted in 10% of infants. HCV-associated cryoglobulinemia, vasculitis and porphyria cutanea tarda are not reported.
During chronic infection, different patterns of biochemical abnormalities are observed. In two large series of 194 and 332 children, respectively, ALT levels were persistently abnormal in 42–45% of patients, normal or normalized in 8–23% and intermittently elevated in 35–41%.[26,27]
The predominant genotypes in European and American children are 1a and 1b (70%), although in recent years, and considering children with vertical transmission, the proportion of genotype 1 infections has decreased to 54%, with a rise in genotypes 3 (23%) and 4 (7%). The viral load does not appear to be correlated to ALT levels or the histologic lesions.
A biopsy is needed for accurate assessment of lesions produced by chronic hepatitis. Although not performed in every affected child, it usually reveals mild lesions. Noninvasive biochemical tests (Fibro-Test and Acti-Test) are being evaluated in children with hepatitis C for their correlation with histology.
In a study of Italian and Spanish children, the histologic activity index (HAI) was found to be low in most patients, with a mean value of 3.6 (range 0–11). The final diagnoses were normal liver histology or with minimal and nonspecific lesions in 17.5% of the cases, chronic hepatitis with a low activity in 60% and high activity in 21%. Those patients with a definitive diagnosis of highly active chronic hepatitis were significantly older on average (12 years) than children with low-activity chronic hepatitis or minimal liver lesions (8 years). Fibrosis was absent in 27.5% of cases, mild in 55% and moderate in 16.2%. Only 1.3% (one of the 80 children) had cirrhosis. A significant relationship was detected between fibrosis scores and duration of disease, portal inflammation and interface hepatitis.
In a later report with additional children (total of 112 cases) fibrosis was assessed by the METAVIR scale. Age of patients at biopsy and duration of infection strongly correlated with fibrosis stage. A strong difference was observed between patients whose infection lasted less and more than 10 years. The mean rate of 'estimated' fibrosis progression in a linear progression model was 0.227 ± 0.372 METAVIR units per year, with a median of 0.142. Theoretically, cirrhosis could develop after a mean time of 28 years. However, the rate of 'observed' fibrosis progression per year in the 13 subjects who underwent paired biopsies was variable among them (seven had increased and six unchanged scores), averaging 0.112 ± 0.14. The progression of fibrosis seems to be a function of the duration of the infection, when no other risk factors for liver damage are present.
Similar histologic findings have been reported in several series, some of which included patients affected by other superimposed conditions to HCV (Table 1).[26,31–34]
A recent report on 121 children without decompensated disease and recruited in several American centers for a therapeutic trial has shown that children with normal ALT were as likely to have significant inflammation as those with elevated ALT levels. Five patients (4.2%) had bridging fibrosis and two (1.7%) had cirrhosis. There was a highly significant correlation of inflammation with fibrosis. In the subset of 94 children with perinatal transmission, there was a weak correlation of estimated duration of disease with inflammation that approached statistical significance. The two children with cirrhosis were both 14 years old, whereas the five with bridging fibrosis were 11–16 years old. The lack of correlation of age or duration of infection with fibrosis might have been due to the small number of patients with advanced fibrosis.
Other authors found the severity of liver disease did not seem to depend on the duration of infection.
Expert Rev Gastroenterol Hepatol. 2010;4(1):51-61. © 2010 Expert Reviews Ltd.
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