[Hemophagocytosis and undifferentiated carcinoma of the lung].

Hemophagocytosis (HP) constitutes a valuable sign in the diagnosis of a number of hematologic diseases such as malignant histiocytosis (MH). It has also been described in the course of hematologic neoplasias being extremely rare in solid tumors. We present the case of a patient with pancytopenia, hepatomegaly, skin lesions and rapidly fatal evolution in whom the finding of HP in bone marrow arouse the suspicion of a MH. The post mortem study revealed the existence of undifferentiated lung carcinoma with a high degree of invasiveness, not finding histiocytic proliferation. The cases in the literature of the association of HP with non hematological neoplasias are revised as well as its possible pathogenic mechanisms. We conclude that MH needs to be considered as a non specific finding and that exhaustive cytochemical studies are necessary for the correct identification of the phagocytic cell.