Microscopic description and IHC:
The H&E stains show sheets of large lymphoid cells effacing normal lung parenchyma. Focally the lymphoid cells invade arterioles producing infarct-like necrosis. On immunostains, the lymphoid cells appear of B-cell lineage (CD20-positive) and coexpress CD30. Significant number of the lymphoid cells (>50/hpf) are also positive for EBER on CISH.
Discussion:
In pulmonary LYG, symptoms include cough, chest pain, dyspnea, and sometimes hemoptysis. Imaging usually shows multiple bilateral lung nodules with predominant basal and peribronchovascular distribution, that can progress rapidly, coalesce and commonly cavitate.
There are three grades of LYG based on the amount of EBER positive cells, with grade I being <5/hpf, grade II 5-50/hpf, and grade III >50/hpf. Treatment is chemotherapy and immunomodulation.