HISTOPATHOLOGY IN ERYTHRODERMA - REVIEW OF A SERIES OF CASES BY MULTIPLE OBSERVERS

This study examines the utility of objective histopathological studies in the evaluation of adult patients with erythroderma. A series of 56 skill biopsies, from 40 erythrodermic patients, was reviewed sequenti ally by 4 Canadian dermatopathologists who were unaware of clinical de tails of the cases. The final diagnosis (gold standard), in each insta nce, had already been determined by others, based on clinicopathologic data and response to therapy. Direct comparison revealed that the mea n accuracy of the histopathological diagnoses was 53% (range: 48-66%), a favorable result in view of the difficulty of the task at hand. Add itional points of information which evolved from the study are as foll ows: (i) identification, by microscopy alone, of spongiotic dermatitis , cutaneous T-cell lymphoma and psoriasis, as underlying causes of ery throderma was more successful than that: of drug eruptions and pityria sis rubra pilaris; (ii) the epidermotropism which characterizes cutane ous T-cell lymphoma may be mistaken for inflammatory interface changes seen in drug eruptions and vice versa, thus constituting a pitfall in diagnosis; (iii) finally, it appears that submission of multiple simu ltaneous biopsies, rather than a single specimen, from patients with e rythroderma would be likely to enhance the accuracy of histopathologic al diagnosis.