Pulmonary lymphomatoid granulomatosis in a 4-year-old girl: A case report

BACKGROUND: Pulmonary lymphomatoid granulomatosis (PLG) is a lymphoproliferative disease associated with Epstein-Barr viral infection occurring mainly in adults and rarely in children. It is characterized by multiple pulmonary nodules. Its diagnosis depends on lung biopsy findings. Most patients are immunodeficient, and it commonly presents in children undergoing chemotherapy for leukemia. We report the case of a child with PLG caused by a mutation in the macrophage-expressed gene 1 (MPEG1), suggesting possible PLG occurrence in children undergoing treatment for pulmonary nodular lesions. CASE SUMMARY: This study reports a case of PLG without apparent immunodeficiency, suggesting the possibility of this disease occurrence during the treatment of pulmonary nodular lesions in children. Initially, the cause was assumed to be an atypical pathogen. Following conventional anti-infective treatment, chest computed tomography findings revealed that there were still multiple nodules in the lungs. Additionally, the patient was found to be infected with the Epstein-Barr virus. Histopathological examination of the resected lung revealed lymphoproliferative lesions with necrosis. Small lymphocytes, plasma cells, and histiocytes were observed in the background, although Reed-Sternberg cells were absent. Immunohistochemical staining [CD20(+), CD30(+), and CD3(+)] and EBV-encoded small RNA1/2 in situ hybridization of small lymphocytes revealed approximately 200 cells/high-power field. Whole exon sequencing of the patient revealed a mutation in the MPEG1. The patient was eventually diagnosed with PLG and transferred to the Department of Pediatric Oncology for bone marrow transplantation. CONCLUSION: As PLG is rare and fatal, it should be suspected in clinical settings when treatment of initial diagnosis is ineffective.