Delta bilirubin with black granules (lipofuscin) is characteristic of which disorder?

• A. DJS
• B. Rotor Syndrome
• C. Gilbert Syndrome
• D. Crigler-Najjar

Answer: (A)

Delta bilirubin is the form of bilirubin that’s still bound to albumin after conjugation, and it stays in circulation longer when excretion into bile is impaired. In Dubin-Johnson syndrome, a defect in the canalicular transporter (MRP2) causes conjugated bilirubin to back up into hepatocytes and be released slowly, producing conjugated hyperbilirubinemia that includes the delta fraction. At the same time, the liver accumulates dark pigment granules called lipofuscin, giving a black appearance that is characteristic of this disorder. This combination is not typical of Rotor syndrome, Gilbert, or Crigler-Najjar, which involve different bilirubin patterns (often unconjugated) and lack the lipofuscin-laden liver. So the description fits Dubin-Johnson syndrome.