Subcategories of histiocytic lymphoma: associations with survival and reproducibility of classification. The Southeastern Cancer Study Group experience.

Five pathologists reviewed histologic slides from 134 cases of histiocytic lymphoma and subclassified these cases using Lukes-Collins classification system. Of 98 morphologically subclassifiable cases, 85 were distributed among three categories, each presumed to represent a lymphoma of follicular center cell origin. The remaining 12 cases were classified among three additional categories. The cases within the three follicular center cell categories, considered collectively, had a significantly better survival than did the cases within the other three categories considered as a whole. The pathologists classified cases generally as being of a follicular center cell type with a high degree of reproducibility, but their individual classifications varied significantly with respect to more specific morphologic categories. Suboptimal quality of histologic sections was a significant factor contributing to problems in morphologic classification. Ancillary immunologic techniques may be required for definitive subclassification of large cell lymphomas.