Coexistence of nontuberculous mycobacterium and IgG4-related disease in a solitary pulmonary nodule: A case report

Clivus-involved immunoglobulin G4 related hypertrophic pachymeningitis mimicking meningioma: A case report

BACKGROUND

Immunoglobulin G4 related disease (IgG4-RD) is a fibroinflammatory disease with markedly elevated serum IgG4 levels and fibrous tissue proliferation, accompanied by numerous plasma cells. IgG4 related hypertrophic pachymeningitis (IgG4-RHP) is relatively rare and indistinguishable from other phymatoid diseases before the operation. The risk of long-term immunosuppression needs to be balanced with disease activity.

CASE SUMMARY

A 40-year-old man presented with headache and bilateral abducent paralysis. He was also diagnosed with pulmonary tuberculosis 10 years ago and was on regular treatment for the same. Before the operation and steroid therapy, the patient was suspected of having tubercular meningitis at a local hospital. A clivus lesion was found via brain magnetic resonance imaging (MRI) at this presentation. He was preliminarily diagnosed with meningioma and underwent Gamma Knife Surgery. Transnasal endoscopic resection was performed to treat deterioration of nerve function. Postoperative pathologic examination suggested IgG4-RD. Moreover, the serum IgG4 was elevated at 1.90 g/L (reference range: 0.035-1.500 g/L). After steroid therapy for 2 mo, the lesion size diminished on MRI, and the function of bilateral abducent nerves recovered.

CONCLUSION

IgG4-RHP is relatively rare and indistinguishable before the operation. Elevated serum IgG4 levels and imaging examination help in the diagnosis of IgG4-RHP. Surgery is necessary when lesions progress and patients start to develop cranial nerve function deficit.

Anti-interferon-gamma autoantibody related disseminated nontuberculous mycobacteriosis with pathological features of immunoglobulin G4-related disease

A 72-year-old man who was diagnosed as pulmonary mycobacterium avium complex (MAC) disease had suffered from antibiotics resistant fever with left renal enlargement surrounded by inflammatory change and multiple osteolytic lesions on computed tomography (CT). The renal biopsied samples pathologically showed immunoglobulin G4 (IgG4) positive plasma cell infiltration and many acid-fast bacilli without granuloma formation. Nucleic acid identification test for MAC from the samples of vertebral osteolytic lesion was positive. In the autopsy samples from left kidney, epithelioid cell granuloma and Langhans giant cell with many acid-fast bacilli were shown pathologically. In addition to osteolytic lesions on CT study, these pathological findings were not consistent with IgG4-related disease (IgG4-RD). The diagnosis of disseminated nontuberculous mycobacteriosis was made, and plasma anti-interferon-gamma (IFN-γ) autoantibody was found as the cause of underlying immunodeficiency. Disturbed function of IFN-γ resulted in impaired ability of phagocytic cells against pathogens and leading to spread of infection. T-helper type 2 dominant immune response was induced by prolonged antigenic stimulation of mycobacteria, which might have contributed to form the pathological features of IgG4-RD.

Imaging characteristics of nontuberculous mycobacterial pulmonary nodules

Introduction: Nontuberculous mycobacteriosis (NTM) of the lungs can develop nodules. In order to clarify some of the characteristics of lung NTM nodules, we examined volume doubling time (VDT) and maximum standardized uptake value (SUVmax) in positron emission tomography (PET) of pathologically diagnosed NTM nodules.Methods: From November 2012 to August 2018, clinical and radiological information were retrospectively investigated in 8 patients who were surgically resected and diagnosed as NTM. These eight patients were followed up until November 2020 and were confirmed to have no appearance of lung cancer or reappearance of lung NTM nodules. The VDT was calculated using the Schwartz formula.Results: The median maximum diameter of the nodule at the time of the first CT scan was 16.0 (range: 9.9-20.0) mm. The median maximum diameter of the nodule on CT performed before the surgical biopsy was 18.8 (range: 10.4-32.8) mm. The median doubling time calculated from these results was 203 (range: 20-568) days. Caseous granulomas and acid-fast bacilli were histologically confirmed in all 8 patients. Culture of excised nodules revealed Mycobacterium intracellulare in 5 patients and Mycobacterium avium in 3 patients. Six patients received PET, and median SUVmax was: 7.0 (range: 3.3-21.0). Median VDT was around 200 days. Some patients had irregular-shaped nodules.Conclusions: CT/PET-CT characteristics of lung nodules are not reliable in differentiating lung NTM nodules from malignant ones. To avoid unnecessary resection, it may be better to collect various information on imaging findings in the nodule itself and in opacities other than the nodule.