Combined immunodeficiency with granulomatosis

Combined immunodeficiency with granulomatosis is a rare primary immunodeficiency disorder characterized by defects in both T-cell and B-cell immunity accompanied by the formation of granulomas in various organs. The ICD-10 code D81.1 corresponds to severe combined immunodeficiency (SCID) related to purine nucleoside phosphorylase (PNP) deficiency, which is one of the recognized causes of combined immunodeficiency associated with granulomatous disease. In PNP deficiency, the accumulation of toxic purine metabolites leads to progressive lymphocyte dysfunction, particularly affecting T cells, with variable impairment of B-cell and natural killer cell function. Patients typically present in infancy or early childhood with recurrent and severe infections, including bacterial, viral, and opportunistic infections. The granulomatous component manifests as non-caseating granulomas that can affect the skin, lungs, liver, lymph nodes, and other organs. Additional features may include autoimmune manifestations such as autoimmune hemolytic anemia, idiopathic thrombocytopenic purpura, and autoimmune thyroid disease. Neurological complications, including developmental delay, spasticity, and ataxia, are also frequently observed in PNP deficiency and help distinguish it from other forms of SCID. The immune system is profoundly affected, with progressive T-cell lymphopenia being a hallmark finding. Immunoglobulin levels may be normal or reduced, but antibody function is typically impaired. Without treatment, the condition is life-threatening due to overwhelming infections. Management includes aggressive treatment of infections, immunoglobulin replacement therapy, and prophylactic antimicrobials. Hematopoietic stem cell transplantation (HSCT) is the definitive treatment and can be curative when performed early. Enzyme replacement therapy and gene therapy approaches are under investigation. Early diagnosis through newborn screening programs that detect T-cell receptor excision circles (TRECs) has improved outcomes by enabling earlier intervention.

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