Cyanosis and extensive erythroid dysplasia in a young adult with hemoglobin M-Hyde Park (Akita)

Cyanosis is an uncommon clinical presentation in infants, children and adolescents, but can manifest from conditions that range from benign to life-threatening. It is often a sign of serious cardiopulmonary disease that affects blood oxygenation levels, and will often present with additional symptoms of dyspnea, jaundice, or splenomegaly. Rare etiologies of cyanosis, including inherited red blood cell disorders, should also be considered. Herein, we report a case of a 17-year-old Japanese male with longstanding cyanosis, progressive anemia, and exercise intolerance with normal cardiopulmonary assessments. Methylene blue provided for the treatment of cyanosis but was ineffective. Laboratory evaluation demonstrated anemia (Hb 10–11 g/dL), macrocytosis (MCV 106 fL), reticulocytosis (9%), and platelets 160–179 × 10⁹/L. Hemoglobin electrophoresis workup showed an abnormal hemoglobin M fraction (~ 10%), and molecular testing confirmed HBB: c.277 C > T (p.His93Tyr), confirming Hemoglobin M-Hyde Park (Akita) disease. After being lost to follow-up and requiring transfusions, he later presented with marked splenomegaly and Hb 7.5 g/dL. A bone marrow biopsy was done which revealed significant erythroid dysplasia, not previously described in this entity. Administration of hydroxyurea reduced transfusion needs, increased fetal hemoglobin to 11%, and stabilized Hb at ~ 9 g/dL. In summary, Hb M-Hyde Park can present with cyanosis and dysplasia. Early genetic studies may prevent misdiagnosis of this rare hemoglobinopathy, for which hydroxyurea is a possible treatment option.