Pulmonary adenocarcinoma with massive lymphocytic infiltration: a case report with review of the literature of a rare histological entity with a peculiar biological behaviour

BACKGROUND: Tumors with a massive inflammatory infiltration are described in several organs. There is agreement about considering the inflammatory infiltration as the host’s immune response to neoplastic cells; such neoplasms indeed have a better prognostic outcome than non-inflammatory counterparts. Only seventeen cases of pulmonary adenocarcinoma with massive lymphocytic infiltration (AMLI) have been reported in literature so far. CASE PRESENTATION: We present a case of pulmonary adenocarcinoma with massive lymphocytic infiltration occurring in a 71 years old male smoker. He came under our attention because of dyspnea, and underwent a left lower lobectomy. Histological examination showed a moderately differentiated (G2) acinar adenocarcinoma associated with a stromal desmoplastic reaction and a massive inflammatory infiltration, made up mostly of CD3+ lymphocytes. pTNM stage was pT2a, N0 (clinical stage: Ib). Molecular testing of EGFR gene showed no mutations and immunohistochemistry for ALK resulted negative. EBV infection was ruled out by EBV in situ hybridization. CONCLUSIONS: Literature review showed seventeen similar cases, with a 16/1 male/female ratio and a mean age of 70,2 years. In eight out of seventeen cases EBV-infection was demonstrated with immunohistochemical or molecular biology techniques. Similarly to the cases previously reported in literature our patient is a male smoker, without lymph node metastasis and he is still alive after a follow-up period of six months without recurrent or residual disease. Because of histological, biological and clinical peculiarity, we propose to take into account pulmonary adenocarcinomas with massive inflammatory infiltration for a separate pathological classification.