Paediatric IgG4-related disease manifesting as recurrent pleural effusion

An adolescent boy presented with breathlessness, loss of appetite and weight, and recurrent pleural effusion for the past 7 months. As tuberculosis, followed by malignancy are the most common disease causes of pleural effusion he was evaluated initially for these two conditions. Pleural fluid cytology was normal and cartridge-based nucleic acid amplification test for tuberculosis was negative. Positron emission tomography CT scan done due to the suspicion of malignancy suggested a large right hydropneumothorax, with diffuse soft tissue thickening and fat stranding. Thoracoscopy-guided pleural biopsy was done, which revealed storiform fibrosis, fragments of fibro-collagenous and fibrofatty tissue with dense lymphoplasmacytic infiltrates, obliterative phlebitis, focal bands of sclerosis and IgG4-positive plasma cells in more than 30% of the plasma cells. A diagnosis of IgG4-related disease was made. The child was treated with steroids and mycophenolate mofetil and the child is doing well.