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Backround: Mastocytosis is a rare disease with a variable clinical course. Pure red cell aplasia has not been frequently reported in association with aggressive systemic mastocytosis. CD30 is often expressed on mast cells in systemic mastocytosis. The CD30-directed antibody-drug conjugate brentuximab vedotin has shown in vitro activity against CD30-positive neoplastic mast cells. We describe a case of systemic mastocytosis with the development of severe hemolytic anemia, pure red cell aplasia, and evidence of weak bone marrow CD30 positivity. Brentuximab vedotin was administered with some evidence of clinical benefit.

Patient: A 64-year-old man presented with fatigue and a 20 pound weight loss. He was found to have transfusion-dependent anemia, a low reticulocyte count, and splenomegaly. Evaluation for gastrointestinal blood loss was unremarkable. Bone marrow biopsy showed mast cell aggregates, spindle-shaped mast cells, CD-2 and CD25-positivity, increased myelopoiesis and dysmegakaryopoiesis, red cell aplasia, eosinophilia, and increased reticulin fibrosis. The D816V c-kit mutation was present, and serum tryptase level was elevated at 114 ng/mL. He later developed Coombs-positive hemolysis and direct hyperbilirubinemia, concerning for mast cell liver infiltration.

Intervention: The patient received high-dose steroids and red blood cell transfusions. Interferon alpha and cladribine were contraindicated, given severe liver dysfunction. He was started on hydroxyurea. He received a dose of brentuximab vedotin 1.8 mg/kg IV. Thirteen days after starting steroids and 10 days after brentuximab, haptoglobin became detectable, and total bilirubin decreased to 18.4 mg/dL from 40.5 mg/dL. Red blood cell transfusion requirements decreased. He then developed severe neutropenia, pneumonia with sepsis, and respiratory failure, requiring intubation, maximal pressor support, and broad-spectrum antibiotics. Despite these measures, he expired.

Discussion/Conclusion: This is a rare case of pure red cellaplasia in the setting of aggressive systemic mastocytosis. Therapeutic options were limited in the setting of liver dysfunction, and therapy with brentuximab vedotin resulted in initial clinical benefit. Brentuximab vedotin is being investigated in patients with advanced systemic mastocytosis or mast cell leukemia.

Backround: Mastocytosis is a rare disease with a variable clinical course. Pure red cell aplasia has not been frequently reported in association with aggressive systemic mastocytosis. CD30 is often expressed on mast cells in systemic mastocytosis. The CD30-directed antibody-drug conjugate brentuximab vedotin has shown in vitro activity against CD30-positive neoplastic mast cells. We describe a case of systemic mastocytosis with the development of severe hemolytic anemia, pure red cell aplasia, and evidence of weak bone marrow CD30 positivity. Brentuximab vedotin was administered with some evidence of clinical benefit.

Patient: A 64-year-old man presented with fatigue and a 20 pound weight loss. He was found to have transfusion-dependent anemia, a low reticulocyte count, and splenomegaly. Evaluation for gastrointestinal blood loss was unremarkable. Bone marrow biopsy showed mast cell aggregates, spindle-shaped mast cells, CD-2 and CD25-positivity, increased myelopoiesis and dysmegakaryopoiesis, red cell aplasia, eosinophilia, and increased reticulin fibrosis. The D816V c-kit mutation was present, and serum tryptase level was elevated at 114 ng/mL. He later developed Coombs-positive hemolysis and direct hyperbilirubinemia, concerning for mast cell liver infiltration.

Intervention: The patient received high-dose steroids and red blood cell transfusions. Interferon alpha and cladribine were contraindicated, given severe liver dysfunction. He was started on hydroxyurea. He received a dose of brentuximab vedotin 1.8 mg/kg IV. Thirteen days after starting steroids and 10 days after brentuximab, haptoglobin became detectable, and total bilirubin decreased to 18.4 mg/dL from 40.5 mg/dL. Red blood cell transfusion requirements decreased. He then developed severe neutropenia, pneumonia with sepsis, and respiratory failure, requiring intubation, maximal pressor support, and broad-spectrum antibiotics. Despite these measures, he expired.

Discussion/Conclusion: This is a rare case of pure red cellaplasia in the setting of aggressive systemic mastocytosis. Therapeutic options were limited in the setting of liver dysfunction, and therapy with brentuximab vedotin resulted in initial clinical benefit. Brentuximab vedotin is being investigated in patients with advanced systemic mastocytosis or mast cell leukemia.

Backround: Mastocytosis is a rare disease with a variable clinical course. Pure red cell aplasia has not been frequently reported in association with aggressive systemic mastocytosis. CD30 is often expressed on mast cells in systemic mastocytosis. The CD30-directed antibody-drug conjugate brentuximab vedotin has shown in vitro activity against CD30-positive neoplastic mast cells. We describe a case of systemic mastocytosis with the development of severe hemolytic anemia, pure red cell aplasia, and evidence of weak bone marrow CD30 positivity. Brentuximab vedotin was administered with some evidence of clinical benefit.

Patient: A 64-year-old man presented with fatigue and a 20 pound weight loss. He was found to have transfusion-dependent anemia, a low reticulocyte count, and splenomegaly. Evaluation for gastrointestinal blood loss was unremarkable. Bone marrow biopsy showed mast cell aggregates, spindle-shaped mast cells, CD-2 and CD25-positivity, increased myelopoiesis and dysmegakaryopoiesis, red cell aplasia, eosinophilia, and increased reticulin fibrosis. The D816V c-kit mutation was present, and serum tryptase level was elevated at 114 ng/mL. He later developed Coombs-positive hemolysis and direct hyperbilirubinemia, concerning for mast cell liver infiltration.

Intervention: The patient received high-dose steroids and red blood cell transfusions. Interferon alpha and cladribine were contraindicated, given severe liver dysfunction. He was started on hydroxyurea. He received a dose of brentuximab vedotin 1.8 mg/kg IV. Thirteen days after starting steroids and 10 days after brentuximab, haptoglobin became detectable, and total bilirubin decreased to 18.4 mg/dL from 40.5 mg/dL. Red blood cell transfusion requirements decreased. He then developed severe neutropenia, pneumonia with sepsis, and respiratory failure, requiring intubation, maximal pressor support, and broad-spectrum antibiotics. Despite these measures, he expired.

Discussion/Conclusion: This is a rare case of pure red cellaplasia in the setting of aggressive systemic mastocytosis. Therapeutic options were limited in the setting of liver dysfunction, and therapy with brentuximab vedotin resulted in initial clinical benefit. Brentuximab vedotin is being investigated in patients with advanced systemic mastocytosis or mast cell leukemia.