An early diagnostic case of noonan syndrome with leukocytosis and pulmonary stenosis

Abstract

Abstract Rationale: Noonan syndrome is a genetic disorder with variable clinical manifestations that affects different systems. Among the multitude of clinical findings, the main characteristics are unique facial traits, low height, and congenital cardiac abnormalities. Recognizing such a syndrome is of great importance because of its involvement of multiple organs. Therefore, a systematic and thorough evaluation according to the guidelines for the assessment and management of Noonan syndrome is needed. Patient concerns: A female infant, 3 months old, presented with a difficult neonatal period (respiratory distress, generalized cyanosis), typical facial dysmorphia, evolutionary height hypotrophy, persistent leukocytosis, factor VII deficit, and severe pulmonary stenosis. Diagnosis: Echocardiography showed severe pulmonary valve stenosis, mild pulmonary regurgitation, a 6.5 mm ostium secundum atrial septal defect, and a persistent ductus arteriosus. Laboratory reports revealed leukocytosis with monocytosis, anemia, and thrombocytopenia, but no infectious source was found. Interventions: In this context, a pulmonary balloon valvuloplasty was performed, with a significant decrease of the transpulmonary gradient. Outcome: The patient was genetically tested, and the reports were positive for Noonan syndrome (mutation in exon 13 of PTPN 11). At 3years of age, she underwent open-heart repair of the atrial septal defect and significant recurrent pulmonary stenosis. The postoperative course was uneventful, and the patient remained asymptomatic at 6months follow-up. Conclusions: The diagnosis was initially suggested by the characteristic unique clinical events associated with cardiac involvement and confirmed later through genetic molecular testing. Prompt treatment of the severe life-threatening pulmonary valve stenosis was important, and the patient underwent additional interventions, after which she remained stable.