Congenital Sideroblastic Anemia with Persistent Neutropenia in a Female Infant: A Case Report of Pyridoxine Responsiveness

Abstract Congenital sideroblastic anemia (CSAs) are a heterogeneous group of rare inherited disorders, characterized by defective heme biosynthesis, mitochondrial iron overload, and ring sideroblasts in erythroid precursors. Infantile-onset CSA, particularly autosomal recessive forms, presents a diagnostic challenge in resource-limited settings due to overlap with common causes of refractory anemia. A 1-year-old female infant, born to first-cousin consanguineous parents, presented with transfusion-dependent severe anemia and persistent neutropenia since the age of 2 months. Serial complete blood counts demonstrated dimorphic anemia (hemoglobin: 3.9–6.6 g/dL), elevated iron indices (ferritin 459 ng/mL, serum iron 280 μg/dL), and persistent neutropenia (absolute neutrophil count [ANC] 228–965/μL). Bone marrow examination confirmed erythroid hyperplasia and numerous ring sideroblasts on Perls' Prussian blue stain. Nutritional deficiencies, hemoglobinopathies, hemolysis, Shwachman–Diamond syndrome, and Pearson syndrome were systematically excluded. Genetic testing was unavailable due to resource constraints. Empirical oral pyridoxine therapy (50–100 mg/d) resulted in near normalization of hemoglobin (11.2 g/dL), resolution of neutropenia (ANC: 1800/μL), and a marked reduction in transfusion requirement over 6 months. This case highlights the importance of CSA in the differential diagnosis of infants presenting with refractory dimorphic anemia, iron overload, and cytopenias—particularly with a history of consanguinity. An empirical pyridoxine trial is warranted even in suspected autosomal recessive forms, as partial or complete responses may occur.