Progressive familial intrahepatic cholestasis (PFIC) is an autosomal recessive disorder, defined by conjugated hyperbilirubinemia with normal serum γ-glutamyl transpeptidase (GGT) values and severe pruritus that progresses to fibrosis in the first months of life (1). Mutations in ATP8B1 are associated with PFIC type 1 (PFIC1) and with instability of the bile-canaliculus membrane (2,3). Mutations in ABCB11 are associated with PFIC type 2 (PFIC2) and with defective expression of bile salt export pump (BSEP) at the bile-canaliculus membrane (4,5). Mutations in ATP8B1 or ABCB11 also may result in “benign” recurrent intrahepatic cholestasis (BRIC; BRIC1 and BRIC2, respectively) marked by recurrent episodes of cholestasis and severe pruritus, with normal GGT values, that last from weeks to months without progression to chronic liver disease (2,6). Both ATP8B1 and ABCB11 disease of intermediate phenotypic expression between PFIC and BRIC are described (7,8). Endoscopic nasobiliary drainage (NBD) can rapidly resolve episodes of BRIC1 in adults (9); its use in adults with BRIC2 or children with BRIC has not been reported. We present a previously healthy 5-year-old child, a compound heterozygote for ABCB11 mutations associated with PFIC2/BRIC2, whose first episode of severe jaundice and pruritus ended shortly after initiation of NBD.
A previously healthy 5-year-old boy, an only child, was admitted to Aghia Sophia Children's Hospital with jaundice, acholic stools, and dark urine for 1 week. A month before admission, the patient developed severe pruritus, attributed to atopic dermatitis. There was no history of fever, diarrhea, or drug ingestion in the last month. There was no family history of consanguinity, autoimmune disease, chronic liver disease, or cystic fibrosis. Vaccinations against hepatitis A and B were complete.
The patient was deeply icteric with severely excoriated extremities. His weight was 14.8 kg (less than 3rd percentile) and height 107 cm (5th percentile). The lungs and heart were normal. The abdomen was nondistended and without ascites. The liver edge was palpated 2 cm below the right costal margin; the spleen could not be felt. Peripheral edema, lymphadenopathy, digital clubbing, and stigmata of chronic liver disease were absent.
Laboratory evaluation revealed a white blood cell count of 10,480 cells/m3, a hemoglobin level of 13 g/dL, and a platelet count of 351,000 cells/m3. Serum total bilirubin was 13.6 mg/dL (N < 1.0) with direct bilirubin 7.6 mg/dL (<0.3), GGT 10 U/L (8–90), alkaline phosphatase 543 U/L (60–240), alanine aminotransferase (ALT) 60 U/L (10–60), aspartate aminotransferase 32 U/L (5–45), lactate dehydrogenase 433 U/L (100–190), and bile acids 320 μmol/L (10–20). Serum electrolyte, albumin, total protein, α-fetoprotein, blood urea nitrogen, and creatinine values were normal, as were prothrombin and partial prothromboplastin times and serum vitamin A, vitamin E, and 25-hydroxy vitamin D levels. Urine and plasma analysis with gas chromatography-mass spectrometry did not identify abnormal bile acid species. In plasma, cholic acid was the major bile acid present (224.32 μmol/L), with lesser amounts of chenodeoxycholic acid (47.95 μmol/L) and hyocholic acid (14.47 μmol/L).
On sonography, the liver was mildly enlarged without fibrosis, and the gallbladder, pancreas, spleen, and kidneys were normal. Findings from magnetic resonance cholangiopancreatography were normal. No evidence of neoplasia was detected. Serum copper and ceruloplasmin values and 24-hour urinary copper excretion were within expected ranges. The α1-antitrypsin phenotype was MM. No serologic evidence of hepatotropic virus infection or autoimmunity was found. Slit-lamp ophthalmologic examination, sweat testing, and audiometry found no abnormalities.
Light microscopy of a percutaneous liver-biopsy specimen showed slight portal-tract fibrosis and mild lymphocytic portal-tract inflammation with substantial centrilobular cholestasis. Bile pigment lay within dilated canalicular lumina and was not found within bile ducts, which were not proliferated. The pigment was pale green, not khaki-colored. Orcein staining demonstrated cuprisomes in periportal hepatocytes. A few polykaryotic hepatocytes were present, without viral inclusions or giant-cell change; instead, the lobule appeared tidy. On immunostaining, BSEP and its homologue multidrug resistance–associated protein 2 were well expressed throughout the lobule. Transmission electron microscopy was not conducted. A clinicopathologic intergrade between BRIC and PFIC was thought to be likely, and as BSEP was expressed (4,5), initial sequencing was directed toward ATP8B1.
Sequencing of ATP8B1 in the patient identified no predictably pathogenic mutations; he proved heterozygous for the common intronic polymorphism c.3531+8G/T (single nucleotide polymorphism [SNP] rs34027711), interpreted to be of no clinical significance. Parental ATP8B1, thus, was not sequenced. Sequencing of ABCB11 in this patient and his parents identified him as a compound heterozygote for 2 predictably pathogenic missense mutations: c.1381A>G (p.Lys461Glu), present in heterozygous state in his father, and c.3148C>T (SNP rs2287616; p.Arg1050Cys), present in heterozygous state in his mother. Each parent, like the patient, proved heterozygous for the known common sequence variation c.1331T/C (SNP rs2287622; p.Val444Ala), known to confer susceptibility to cholestasis (10). The paternal mutation is described in homozygous state in a patient of Greek parentage with PFIC2 (11). BSEP was expressed, albeit with focal deficiency, in the liver of that patient (personal observations, A.S.K.). The maternal mutation is described in homozygous state in 2 Italian patients with BRIC2 (6), without information on liver BSEP expression. In vitro expression of ABCB11 harboring this mutation yielded both mature and immature BSEP (10). These findings are consistent with the presence of immunohistochemically detectable BSEP in our patient's liver.
The patient was treated with ursodeoxycholic acid, fat-soluble vitamins, and medium-chain triglyceride–enriched formula. Pruritus improved mildly with topical emollients, hydroxyzine, and rifampin; however, 6 weeks after admission cholestasis worsened, with total and direct bilirubin values rising to 28 and 18 mg/dL, respectively. Partial external biliary diversion was offered, but the parents declined. Thus, NBD was attempted using a pediatric side endoscope. The procedure was unsuccessful; clinical pancreatitis developed and quickly resolved during 5 days of intravenous fluid maintenance. Although the common bile duct could not be cannulated, serum total bilirubin fell to 13 mg/dL (Fig. 1) (12) immediately after the attempt. Five days later, it had again risen to 25.8 mg/dL and a 6-F nasobiliary drain was placed in the common bile duct after sphincterotomy. After 24 hours, biliary drainage averaged 250 mL daily during the first 10 days and 1 L daily for the 2 weeks thereafter (24 days total). Surveillance bile cultures were obtained once per week. In the second week after NBD, Enterococcus faecium was cultured from bile, whereas in the third week, Klebsiella oxytoca, Enterobacter cloacae, and Vibrio fluvialis were cultured. The child, although afebrile, received intravenous antibiotics. NBD was tolerated well; it was associated with both relief from pruritus and gradual falls in serum total and direct bilirubin and bile acid values (Fig. 1). After 7 days of NBD, serum bile acid values had fallen from 450 to 298 μmol/L. On day 24, they had normalized at 4 μmol/L. Serum bilirubin values declined gradually, reaching the normal range approximately 3 weeks after NBD began. After 18 days of NBD, pruritus decreased from grade III (severe itching that interferes with daytime and nighttime activities with excoriations) to grade I (mild daytime itching; pruritus grading scale of Yerushalmi et al (12)). During the last 27 months (as of this writing), jaundice has not recurred in our patient, total bilirubin has been at most 1.5 mg/dL, and serum ALT values have been normal. Intermittent mild nighttime pruritus continues and serum concentrations of bile acids have ranged between 4 to 320 μmol/L, although for the last 6 months they have been normal. A liver biopsy specimen obtained 1 year after NBD ended contained no accumulations of bile pigment, although occasional diastasis of canalicular walls was seen. A sparse mononuclear-leukocyte inflammatory infiltrate was present in lobule and portal tracts, without worsening of fibrosis. Transmission electron microscopy found sparse amorphous bile in rare canalicular lumina.
This child was clinically well before age 5 years, when pruritus developed and progressed to jaundice, with normal GGT values despite conjugated hyperbilirubinemia. He thus did not meet clinical criteria for usual PFIC. Because evidence for bile acid synthesis disorder was lacking and as no antecedent event or accompanying illness (drug exposure, neoplasia) was identified, a presenting episode of BRIC was diagnosed. At biopsy, however, portal-tract fibrosis, albeit slight, and deposits of metallothioneins indicated chronic cholestasis. These histopathologic considerations suggest an intergrade between classic BRIC and classic PFIC (7,8).
ATP8B1 and ABCB11 are the 2 genes to date principally implicated in intrahepatic cholestasis, without dysmorphism, that is not associated with a rise in GGT values (1). In our patient, BSEP expression was unremarkable. ATP8B1 thus was preferred to ABCB11 for initial sequencing; however, no pathogenic mutations were identified in ATP8B1. When ABCB11 was sequenced, 2 mutations were found; each parent carried a different one of the two. Homozygosity for 1 mutation, c.1381A>G (p.Lys461Glu), has been associated with PFIC2 (11), and homozygosity for the other, c.3148C>T (p.Arg1050Cys), has been associated with BRIC2 (6). Liver-biopsy findings in the patient with BRIC2 are not reported. In the patient with PFIC2, however, BSEP expression was detected immunohistochemically in materials obtained at transplant hepatectomy aged 6 years (personal observations, A.S.K.). In addition, the BRIC-associated mutation in culture was associated with expression of BSEP (10). Given the ABCB11 mutations documented in this patient, expression of BSEP despite cholestasis can be explained.
This child's cholestasis resolved, as judged by disappearance of jaundice with near-normalization of clinical laboratory test results and by amelioration of pruritus, within 24 days after NBD began (Fig. 1). Was this due to NBD placement or to a change in bowel flora associated with the administration of antibiotics in prophylaxis? Was it a nonrelated and spontaneous termination of an episode of BRIC? We cannot conclusively exclude the possibility that the amelioration observed was unrelated to intervention with NBD, but we provisionally ascribe resolution of cholestasis in our patient, at least in part, to the off-loading of bile acids, depletion of the body bile acid pool, and reduction of the hepatocellular bile acid burden that NBD entrains. Certainly, the improvement in clinical and biochemical parameters of cholestasis was more gradual in our patient than in the adult patients with BRIC due to ATP8B1 mutations reported by Stapelbroek et al (9). We believe, however, that because the pathophysiology of ABCB11 disease, present in our patient, inherently differs from that of ATP8B1 disease, to expect the natural histories of the 2 disorders, and their responses to various interventions, to be the same may be unjustified.
The natural history of BRIC2 is almost entirely undescribed, hitherto comprising, to our knowledge, 4 reports and 14 subjects, of whom only a few were children. Recurrent cholestatic attacks last from several weeks to several months (6,13). The initial episode of jaundice in a 17-year-old boy began at age 3 months; he had further cholestatic attacks at ages 2, 4, and 9 years, each lasting at least 3 months (13). The duration of bouts of cholestasis was not described in 11 patients ages 15 to 46 years with cholestasis manifesting as early as age 2 months (6); neither age of onset nor duration of bouts was described in a single boy age 16 years (14) or a single boy age 9 years (15). Pruritus antedated icterus in our patient by 1 month, with frank jaundice, including the 24-day period of NBD, lasting for approximately10 weeks. The morbidity caused by BRIC in our patient was substantial, with malaise, fat malabsorption, and severe pruritus. His cholestasis did not respond to usual interventions. If indeed NBD accelerated resolution of his signs and symptoms, its use was of considerable value to the patient and his family. Biliary diversion has been discussed with the family, if fibrosis worsens (16–18). Monitoring continues for hepatobiliary neoplasia associated with ABCB11 mutation (19,20).
Although NBD in adults with ATP8B1 mutation and BRIC shortened bouts of cholestasis (9), results of NBD in adults with ABCB11 mutation and BRIC have not been reported, nor has NBD in children with BRIC and either ATP8B1 or ABCB11 mutation been described. Our experience suggests that NBD may warrant trials in adults with ABCB11 mutation and BRIC. It also encourages us to attempt NBD in other children with BRIC, a disorder with few options for treatment.
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