IgG4-Related Lung Disease in a Patient with Chronic Granulomatous Disease: A Case Report.

Background: IgG4-related disease may initially present with pulmonary pseudotumor, making the diagnosis challenging particularly in patients prone to granulomatous inflammation. Here, we describe the first case of chronic granulomatous disease with associated lung IgG4RD. Case Presentation: An 8.5-year-old male was hospitalized two years ago with exertional dyspnea, mild cough, chest pain, and nocturnal sweating and was found to have a tumor-like mass in the right lung. The histopathologic findings were consistent with extensive peripheral fibrosis and infiltration of mixed inflammatory cells without any evidence of acid-fast bacilli/fungal elements. Treatment with prednisolone resulted in considerable symptom resolution. Following the discontinuation of prednisolone by the patient, symptoms recurred, gradually exacerbated, and he developed anorexia and weight loss. The next chest spiral computed tomography (CT) scan showed a larger mass in the right lung, right lung collapse, and mediastinal metastasis. The abdominal ultrasound and CT scan were normal. In laboratory evaluation, low counts of B and T cells, normal natural killer cells, high levels of IgG4, and high inflammatory markers were detected. The nitro blue tetrazolium test was zero in two consecutive evaluations. In virtue of high IgG4 level, organ-specific mass, notable tissue fibrosis, and mixed inflammatory cell infiltrate, he was diagnosed with concurrent CGD and IgG4RD, but progressed to respiratory failure and died despite the reinstitution of steroid therapy. Conclusion: The overlap between inborn errors of immunity and IgG4RD is not common. Further studies to investigate IgG subsets among IEI patients can help elucidate clinicopathological correlations between these two immune-mediated disorders.