A study of the histopathology of palmo-plantar psoriasis and hyperkeratotic palmo-plantar dermatitis

Background and Objectives: Palmo-plantar psoriasis and dermatitis show several overlapping clinical features. We undertook this retrospective study to elucidate and compare the histological findings in these two dermatoses. Materials and Methods: Biopsies of 31 clinically diagnosed cases of palmo-plantar psoriasis and 24 cases of hyperkeratotic palmo-plantar dermatitis, with concomitant presence of representative lesions at other body sites, were retrieved and analysed. Results: Histologically, confluent parakeratosis, suprapapillary thinning and dermal edema were observed in significantly greater number of palmo-plantar psoriasis biopsies while an inflammatory infiltrate confined to the papillary dermis only, was a significant feature in palmo-plantar dermatitis. The two conditions could not be differentiated on the basis of features like focal parakeratosis, presence of neutrophils and fibrin globules in the stratum corneum, hypogranulosis, acanthosis, spongiosis, rete ridge pattern, or vascularity. Conclusion: Histopathology of palmo-plantar psoriasis and dermatitis can have several overlapping features. In our study, we found only few features as strong pointers towards psoriasis.