1Department of Internal Medicine, Christus Highland Medical Center, Shreveport, LA, USA.
2Department of Gastroenterology and Hepatology, Christus Highland Medical Center, Shreveport, LA, USA.
3Division of Gastroenterology and Hepatology, Louisiana State University Health Center, Shreveport, LA, USA.
4Department of Gastrointestinal and Liver Pathology, Christus Highland Medical Center, Shreveport, LA, USA.
Antimitochondrial antibody-positive primary biliary cholangitis (AMA-pos PBC) is an autoimmune disorder in which monoclonal antibodies are produced against epitopes in the mitochondrial membranes of biliary epithelial cells, resulting in progressive nonsuppurative biliary cholangitis. Up to 5% of patients lack these autoantibodies, termed antimitochondrial antibody-negative (AMA-neg) PBC. Although a somewhat new variant of AMA-pos PBC, it is not an overlapping syndrome. Few studies to date have described this phenomenon. An 87-year-old woman was referred to our clinic with elevated serum alkaline phosphatase (714 U/L). She reported fatigue but no other symptoms. A physical examination revealed a benign lesion and bilateral lower extremity swelling secondary to lymphedema. The serological profile was significant for a high antinuclear antibody titer (>1:2,560) with a centromere pattern and negative for antimitochondrial antibody (AMA). The hepatitis panel was negative for viruses A, B, and C. Her serum immunoglobulin G level was 871 mg/dL (normal, <1,600 mg/dL). The rest of the serological tests, including anti-smooth muscle antibodies (ASMA) and anti-liver/kidney microsomal antibodies, were negative. Computed tomography of the abdomen and pelvis without contrast showed normal liver parenchyma and no acute intra-abdominal pathology. Histopathology indicated florid duct lesions. The background parenchyma showed no significant steatosis, and inflammatory changes were limited to the portal areas. Periodic acid-Schiff staining revealed intact hepatic parenchyma and architecture. The patient was diagnosed with AMA-neg PBC and responded well to ursodeoxycholic acid therapy. This case highlights the importance of recognizing AMA-neg PBC as a variant of AMA-pos PBC and differentiating between them. Autoimmune cholangitis is a vague and imprecise condition. All patients with AMA-negative PBC should be tested for other PBC-specific autoantibodies. Although the prognosis and bile duct damage and loss are worse in AMA-neg PBC for unknown reasons, treatment remains the same for both.