Review Question - QID 212813

This patient has hereditary spherocytosis (e.g., cholecystitis secondary to probable pigment gallstones, splenomegaly, pale conjunctiva, and hereditary “blood condition”). The disease can be diagnosed via a positive osmotic fragility test.

Hereditary spherocytosis causes extravascular hemolysis due to a red cell membrane defect. It is caused by variants in genes that are responsible for linking the RBC inner membrane skeleton to the outer lipid bilayer (e.g., spectrin, Ankyrin, band 3, and protein 4.2). These defects result in small, round RBCs with less surface area and no central pallor and are thus prematurely removed by the spleen. Clinical presentation is highly variable and can range from mild hemolytic anemia to hydrops fetalis in utero. Patients often have a positive family history and symptoms of hemolytic anemia (e.g., laboratory abnormalities including low hemoglobin and mean corpuscular volume, fatigue, or pale conjunctiva). Complications of hemolysis include neonatal jaundice, splenomegaly, and pigment gallstones.

Figure/Illustration A is an ultrasound image of the gallbladder with stones (arrows).

Incorrect Answers:
Answer 1: A blood smear demonstrating RBCs with Heinz bodies and bite cells can be seen in G6PD deficiency. Patients often present with hemoglobinuria and pain days after oxidant stress (e.g., fava beans, sulfa drugs, infections, or antimalarials).

Answer 2: CD55/59 negative RBCs on flow cytometry are seen in paroxysmal nocturnal hemoglobinuria, which presents with red or pink urine.

Answer 3: An elevated hemoglobin and hematocrit is associated with polycythemia vera. This disease presents with pruritis and gouty arthritis, but not gallstones.

Answer 4: Low hemoglobin with decreased mean corpuscular volume is a nonspecific finding for a variety of microcytic anemias (e.g., iron deficiency anemia).

Bullet Summary:
Hereditary spherocytosis can be diagnosed via a positive osmotic fragility test.