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Diagnostic dilemma of a 13-month-old boy with 'late-onset' combined immunodeficiency
Insights
This study details a rare late-onset combined immunodeficiency case in a 13-month-old boy with severe Pneumocystis pneumonia. The findings highlight profound T-cell dysfunction and reduced immunoglobulin levels, impacting immune response.
Area of Science:
- Immunology
- Pediatric Medicine
- Genetics
Background:
- Combined immunodeficiency (CID) disorders are a group of rare genetic conditions affecting the immune system.
- Late-onset CID presents diagnostic challenges, often mimicking other conditions.
- Pneumocystis pneumonia (PCP) is a severe opportunistic infection frequently seen in immunodeficient individuals.
Observation:
- A 13-month-old boy presented with a month-long history of severe Pneumocystis carinii pneumonia.
- Clinical evaluation revealed a lack of cutaneous delayed hypersensitivity responses and impaired lymphocyte proliferation.
- Immunoglobulin analysis showed normal IgM but markedly reduced other immunoglobulin classes.
Findings:
- The patient exhibited a late-onset form of combined immunodeficiency characterized by significant T-cell defects.
- Histopathological examination revealed a dysplastic thymus lacking Hassall's corpuscles and thymocytes.
- Lymphoid organs showed a marked depletion of T-dependent areas, indicating a severe disruption of immune cell organization.
Implications:
- This case underscores the importance of considering late-onset CID in infants presenting with opportunistic infections like PCP.
- Understanding the specific immunological deficits can guide therapeutic strategies and genetic counseling.
- Further research into the genetic basis of such late-onset CID forms is crucial for improved diagnosis and treatment.
Abstract:
A 13-month-old boy had a "late-onset" form of combined immunodeficiency and a fulminant Pneumocystis carinii pneumonia of one month's duration. There was no evidence of cutaneous-delayed hypersensitivity responses to diphtheria-tetanus toxoids, Candida albicans, or streptokinase-streptodornase, or of lymphocyte DNA synthesis after in vitro stimulation with the mitogens phytohemagglutinin and concanavalin A, and only 2% to 4% of peripheral blood E-rosetted T lymphocytes. The serum IgM level was normal (62 mg/dL), whereas the other immunoglobulins were markedly reduced. Despite an increased number of Ig-bearing lymphocytes, in vitro Ig secretion after pokeweed mitogen stimulation was substantially reduced. The thymus gland was dysplastic with no Hassalls' corpuscles or thymocytes, and other lymphoid organs showed depletion of T-dependent areas to a greater extent than the B-dependent areas.