The histopathological differentiation between palmar psoriasis and hand eczema: A retrospective review of 96 cases.

BACKGROUND: The histopathologic differences among palmar psoriasis (PP), hand eczema (HE), and hyperkeratotic hand dermatitis (HHD) have been poorly described. OBJECTIVES: We sought to distinguish among PP, HE, and HHD on a histopathologic basis. METHODS: We retrospectively analyzed the histology of hematoxylin-eosin-stained sections obtained from 96 patients diagnosed with PP, HE, or HHD. RESULTS: The patients were divided into 4 subgroups: PP (n = 16, group A), HE without atopic or nummular dermatitis (n = 41, group B), HE with atopic or nummular dermatitis (n = 14, group C), and HHD (n = 25, group D). Loss of the granular layer (group A 62.5%, group B 24.4%, group C 0%) was more consistent with a diagnosis of PP (P = .047) than HE (P = .002). Psoriasiform epidermal hyperplasia (group B 36.6%, group C 35.7%, group D 72.0%) favored a diagnosis of HHD (P = .01) over HE (P = .043). LIMITATIONS: Limitations of this study include its retrospective nature and small sample size. CONCLUSION: Our study demonstrated that a significant difference exists in the thickness of the granular layer between PP and HE, which might be helpful in differentiating between these 2 conditions. There was no difference between PP and HHD.