[Primary pulmonary pseudolymphomas and lymphomas. 4 cases].

We report four cases of primary pulmonary pseudolymphoma and lymphoma with the usual features of these disorders: lack of symptoms, radiological opacities sometimes multiple with soft wooly contours and air bronchograms, and slowly evolving pattern. The distinction between pseudolymphoma and lymphoma, prior to histological diagnosis is currently controversial. Immunological studies aim at defining whether the lymphoid proliferation is polyclonal or monoclonal (the benign process being considered polyclonal and the malign monoclonal). This distinction works in some cases, as in one of our cases of lymphoplasmacytic lymphoma with a monoclonal IgM gammopathy, a predominance of cells containing IgM on immunofluorescence, and an illness evolving over 9 years. Other cases raise discussion points such as one of our patients with classical histological characteristics of pseudolymphoma, an absence of monoclonal markers on immunofluorescence, but having a monoclonal gammopathy in the serum. This example raises the question as to the possible coexistence of, or a switch over from, a polyclonal to a monoclonal process. In this way the primary pulmonary lymphoproliferative process ought to be considered as one element in a large spectrum ranging from benign to malign disorders and not as distinct illnesses with definitive patterns.