Classification and terminology of hepatic allograft rejection: whither bound?

The current classification of hepatic allograft rejection recognizes "acute rejection" and "chronic rejection." Although these terms convey duration, implicitly they have been defined on the basis of their morphologic manifestations. This usage causes contradictions in reports and publications because features of "chronic rejection" may occur acutely and vice versa. In the future, biopsy reports, clinical communications, and, in particular, evaluation of treatment might benefit from use of a classification and terminology that more clearly distinguish clinical and morphologic findings and that reserve "acute" and "chronic" for describing the duration of episodes of rejection and terms such as "cellular rejection" or "arteriopathic rejection" for biopsy reporting. Severity should be graded independently for clinical, laboratory, and morphologic findings, inasmuch as an overall grading is not always meaningful--for example, severe cellular rejection may be mild in terms of prognosis, whereas histologically mild rejection may prove incurable. For an overall evaluation of graft rejection, adjectives such as "mild" or "severe" should be replaced or at least supplemented by terms that describe results of treatment and thus prognosis, and a designation should be added for duration and histology--for instance, "acute rejection, cellular, corticosteroid-responsive." Use of such a well-defined clinicopathologic classification of rejection and precise terminology might improve documentation and communication; it might even become a prerequisite for the evaluation of treatment trials.