Pearson syndrome: expanding the clinical spectrum of a mitochondrial cytopathy-a case report.

BACKGROUND

Pearson syndrome (PS) is a rare multisystem mitochondrial disorder characterized by single large-scale mitochondrial DNA deletions (SLSMDs). It typically presents in infancy with refractory sideroblastic anemia, exocrine pancreatic insufficiency, and failure to thrive. Due to its heterogeneous manifestations and resemblance to other hematological conditions, early diagnosis remains a clinical challenge.

CASE PRESENTATION: A south asian male infant presented with persistent pancytopenia, severe anemia unresponsive to intravenous and oral iron and multivitamin supplements, exocrine pancreatic insufficiency, failure to thrive, and metabolic acidosis. Born to consanguineous parents, the child had a significant family history of early infant deaths and hematological abnormalities. Peripheral smear showed marked anisopoikilocytosis with cytoplasmic vacuolization of erythroid precursors. Bone marrow analysis revealed erythroid hyperplasia, dyserythropoiesis, vacuolated precursors in both the erythroid and myeloid lineages, and ringed sideroblasts. Steatorrhea was consistent with exocrine pancreatic insufficiency, a recognized feature of Pearson syndrome. Although HbA1c was marginally elevated, this finding is nonspecific in infancy and does not indicate endocrine pancreatic dysfunction. Endocrine involvement is typically reported later during mitochondrial disorders and was not supported clinically or biochemically in this case. While mitochondrial DNA deletions underlying Pearson syndrome are usually sporadic, the presence of consanguinity and multiple affected siblings in this family raises the possibility of modifying nuclear genetic factors contributing to phenotypic variability. The overall constellation of clinical features, hematological findings, and bone marrow morphology was diagnostic of Pearson syndrome.

CONCLUSIONS

This case underscores the importance of considering mitochondrial cytopathies in infants presenting with unexplained pancytopenia, multisystem involvement, and a suggestive family history, even in the presence of parental consanguinity. Early recognition, even in resource-limited settings, is vital for prognostication and family counseling, though definitive treatment remains supportive.