Lymphomatoid granulomatosis: a practical review for pathologists dealing with this rare pulmonary lymphoproliferative process.

Lymphomatoid granulomatosis (LYG) is a rare B-cell lymphoproliferative disorder predominantly involving the lungs, but poorly-recognized among clinicians and pathologists. It is an Epstein-Barr virus (EBV)-driven disease mimicking several other diseases on clinical and radiological grounds, generally showing multiple, bilateral nodular, ill-defined infiltrates of the lungs tending to coalescence and/or cavitation. LYG often affects middle-aged males with an underlying immunodeficiency and commonly involves skin and central nervous system during disease progression. Diagnosis requires a generous biopsy and careful histologic examination with immunohistochemical staining and molecular demonstration of EBV genome in large atypical B-cells. LYG is graded as I to III based on the number of large EBV-positive B-cells; grades II/III are now considered as a peculiar variant of T-cell rich diffuse large B-cell lymphoma. In this brief review, clinical, radiologic and pathologic features of LYG will be analyzed with focus on differential diagnosis, the most appropriate treatment and prognosis.