Excessive Inflammatory Response to Bacterial Lymphadenitis in an Infant With A Family History of Recurrent Lymph Node Swelling: A Case Report

Suppurative lymphadenitis in infancy typically responds well to antimicrobial therapy. However, some cases exhibit elevated inflammatory markers relative to clinical severity, raising questions about host inflammatory regulation. We report a one-month-old female infant with suppurative lymphadenitis caused by methicillin-sensitive Staphylococcus aureus (MSSA). Despite an appropriate clinical response to treatment, she demonstrated elevated ferritin (446 ng/mL) and soluble IL-2 receptor (1,734 U/mL). Systematic evaluation excluded hemophagocytic lymphohistiocytosis and primary immunodeficiency. Family history revealed recurrent lymph node swelling in the maternal lineage. Exploratory genetic testing identified a heterozygous LRBA gene variant (c.8417A>T), classified as a variant of uncertain significance. This case illustrates the importance of systematic evaluation when inflammatory markers appear elevated relative to clinical presentation. The identified LRBA variant is of uncertain significance and does not establish causality. Long-term follow-up is warranted to clarify whether this represents a clinically meaningful phenotype.