Pulmonary lymphoid neoplasms.

The majority of pulmonary lymphomas have a distribution that follows lymphatic routes and a monomorphous (in the case of lymphocytic and large-cell lymphomas) cell population. Mixed-cell lymphomas show a similar distribution and a cytologic composition identical to mixed-cell lesions in lymph nodes. The term homogeneous may be preferable to monomorphous for lymphoplasmacytic lymphomas (such as Waldenström's macroglobulinemia) and mixed cell lymphomas, as their composition is similar from field to field in contrast to inflammatory lesions, which show geographic cellular heterogeneity and variable scarring.