Differential Diagnosis for a 5-month-old Boy with Recurrent Infections
- Single Most Likely Diagnosis
- Severe Combined Immunodeficiency (SCID): The patient's history of recurrent severe infections (otitis media, oral candidiasis, and gastroenteritis due to rotavirus), low weight percentile, and laboratory results showing significantly low levels of immunoglobulins (IgG, IgA, IgM) and lymphocytes (CD4+ and CD8+ counts) are highly suggestive of SCID. This condition is characterized by a severe deficiency in both T and B cell function, leading to an increased susceptibility to infections.
- Other Likely Diagnoses
- Combined Immunodeficiency: Similar to SCID but may not be as severe, with some residual immune function. The patient's ability to mount some response to infections (e.g., fever) might suggest a less severe form of immunodeficiency.
- Thymic Dysplasia: A condition where the thymus does not develop properly, leading to T cell deficiencies. The patient's low CD4+ and CD8+ counts could be indicative of thymic dysfunction.
- Do Not Miss Diagnoses
- HIV Infection: Although less likely given the age and no mention of maternal risk factors, HIV can cause similar immunodeficiency symptoms. It is crucial to rule out HIV due to its significant implications for treatment and prognosis.
- Leukocyte Adhesion Deficiency (LAD): Characterized by recurrent infections and impaired wound healing due to defects in leukocyte adhesion. While the patient's symptoms could fit, specific tests for LAD (e.g., CD18 expression) are not provided.
- Rare Diagnoses
- DiGeorge Syndrome: A condition characterized by thymic hypoplasia, leading to T cell deficiency, along with other congenital anomalies. The patient's presentation could be consistent with DiGeorge Syndrome, but typical features like cardiac defects, cleft palate, or distinct facial features are not mentioned.
- Wiskott-Aldrich Syndrome: An X-linked recessive disorder characterized by eczema, thrombocytopenia, and recurrent infections due to immunodeficiency. The absence of eczema and thrombocytopenia in the patient's presentation makes this diagnosis less likely.
- Hyper-IgM Syndrome: Characterized by elevated IgM levels with low IgG and IgA levels, often due to a defect in CD40 ligand on T cells. The patient's immunoglobulin profile does not support this diagnosis, as IgM is actually low.