Isolated Pauci-Immune Pulmonary Capillaritis in a Pediatric Patient with a Homozygous Variant in the Mannose-Binding Lectin (MBL2) Gene: A Case Report

Eltahir S1*, Alotaibi W1, Althakfi W2, Saleh M3, Alsadoon H1, Alanazi A1, Mukhtar G1 and Alzaid M1

1Department of Pediatrics, Section of Pulmonary Medicine, King Fahad Medical City, KSA
2Department of Pathology and Histology, King Fahad Medical City, KSA
3Department of Pediatrics, Section of Genetic and Metabolic Medicine, King Fahad Medical City, KSA

^*Correspondance to: Safa Eltahir 

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Abstract:

Background: Isolated Pauci-Immune Pulmonary Capillaritis (IPPC) is a rare condition characterized by Diffuse Alveolar Hemorrhage (DAH) with underlying pulmonary capillaritis, occurring in the absence of clinical, serologic, and histologic findings indicative of an associated systemic disorder. The challenging nature of its presentation and infrequency make IPPC a diagnostic challenge. Due to a lack of data on this entity in children, we present a confirmed case of IPPC in a male child with a homozygous variant in the Mannose-Binding Lectin (MBL2) gene. MBL2 deficiency has been linked to susceptibility and severity modulation in viral, bacterial, fungal, and protozoan infections, as well as associations with rheumatoid and autoimmune disorders such as Systemic Lupus Erythematosus (SLE) and Kawasaki disease. However, it has not been previously reported in conjunction with isolated pauci-immune pulmonary capillaritis. Case Report: We describe a 2-year-old Saudi male child, previously medically and surgically unremarkable until 16 months of age. At this point, he experienced recurrent admissions marked by acute episodes of significant pallor, progressive respiratory distress, lung opacities, and two instances of dark urine passage, requiring blood transfusion and iron therapy. Broncho-Alveolar Lavage (BAL) and wedge lung biopsy confirmed pulmonary hemorrhage and isolated pauciimmune pulmonary capillaritis, respectively. Molecular testing revealed a homozygous variant in Mannose-Binding Lectin 2 (MBL2), NM_000242.2: c.154C>T p.(Arg52Cys). Conclusion: This case, to the best of our knowledge, represents the first instance of confirmed isolated pauci-immune pulmonary capillaritis associated with a homozygous mutation in the MBL2 gene. The findings suggest a potential association between isolated pauci-immune capillaritis and MBL2. Further studies and investigations are warranted to elucidate the role and contribution of MBL in isolated pauci-immune pulmonary capillaritis, specifically, and small vessel vasculitis in general.

Keywords:

IPPC; MBL2; DAH; Children; Pediatric

Cite the Article:

Eltahir S, Alotaibi W, Althakfi W, Saleh M, Alsadoon H, Alanazi A, et al. Isolated Pauci-Immune Pulmonary Capillaritis in a Pediatric Patient with a Homozygous Variant in the Mannose-Binding Lectin (MBL2) Gene: A Case Report. Ann Clin Case Rep. 2024; 9: 2646..