British Society for Dermatopathology

DP01 Hyperkeratotic hand and foot eczema versus palmoplantar psoriasis: can histopathology help clinch the diagnosis? M.M. Aarif Syed and D.P. Shrestha All India Institute of Medical Sciences, Patna, India and Institute of Medicine, Kathmandu, Nepal The presence of clinical overlap between hyperkeratotic hand and foot eczemas (HHFE) and palmoplantar psoriasis (PPP) may present a diagnostic dilemma. However, overlap is not restricted to clinical presentation; the two conditions may share several similar histological features. This study aimed to evaluate the histopathological findings in HHFE and PPP and elucidate the differentiating features of the two. We retrospectively analysed 89 haematoxylin and eosin-stained sections, reported by the department of pathology, which were submitted with differential diagnoses of HHFE and PPP. On the basis of histopathology reports, patients were categorized into two groups: group A (HHFE) and group B (PPP). The histopathological findings of both the groups were recorded and compared using Fisher’s exact test. Group A (HHFE) had 65 patients [30 males (46%), 35 females (54%); mean age 39.8 years], while in group B (PPP) there were 24 patients [11 males (46%), 13 females (54%); mean age 42.9 years]. Hyperkeratosis (group A/B: 43%/37%; P = 0.80), parakeratosis (group A/B: 37%/67%; P = 0.01) and orthokeratosis (group A/B: 26%/21%; P = 0.78) were regularly seen in both HHFE and PPP, but only parakeratosis was a statistically significant feature of PPP. Neutrophils in stratum corneum (50%, P < 0.001) and dilated capillaries (25%; P < 0.001) were exclusive features of PPP. Hypergranulosis (HHFE: 49%) and hypogranulosis (PPP: 75%) were statistically significant features of HHFE and PPP (P < 0.001). Acanthosis (group A vs. group B: 80% vs. 67%; P = 0.26), spongiosis (group A vs. group B: 81% vs. 54%; P = 0.01) and lymphocytic exocytosis (group A vs. group B: 45% vs. 21%; P = 0.05) were more consistent findings in HHFE. Spongiotic vesicles (5%; P = 0.56), apoptotic bodies (3%; P = 1.0), degeneration of basal layer (9%; P = 0.18), plasma cells in epidermis (3%; P = 1.0) and eosinophilic infiltrate in upper dermis (3%; P = 1.0) were only evident in a few cases of HHFE. Suprapapillary thinning (group A/B: 1%/50%; P < 0.001) and elongation of rete ridges (group A/B: 32%/79%; P < 0.001) were defining features of PPP. Infiltrate in the upper dermis was primarily lymphocytic in both groups (group A vs. group B: 92% vs. 92%; P = 1.0); however, occasional plasma cells (group A vs. group B: 18% vs. 21%; P = 0.77) and neutrophils (group A vs. group B: 12% vs. 21%; P = 0.32) were also observed. Other histological findings, which included neutrophils in stratum spinosum, psoriasiform hyperplasia, intraepidermal vesicles and papillomatosis were infrequently seen in both groups. Histopathological differences among HHFE and PPP have been poorly described. The characteristic features of PPP in our study were collections of neutrophils within the stratum corneum, parakeratosis, diminished to absent granular layer, suprapapillary thinning, elongation of rete ridges and dilated tortuous capillaries. Hypergranulosis was an exclusive, while spongiosis was a more consistent, feature of HHFE.