Table 1.

Differential diagnosis of chronic acral hyperkeratotic dermatosis

Diagnosis	Clinical features	Histopathology
Psoriasis [12]	Pruritic well-defined, symmetrical erythematous plaques with silvery-white scaling over extensor surface of the body. Auspitz sign positive. Involvement of scalp, joint, and nails often present	Hyperkeratosis, parakeratosis, absent granular layer, acantosis with regular elongation of the rete ridges, suprapapillary thinning of epidermis, papillary dermal edema with dilated capillaries surrounded by lymphocytic infiltrate. Munro microabscesses in the stratum corneum, spongiform pustules of Kogoj in the spinous layer
Hypertrophic lichen planus[13]	Pruritic violacious, shiny verrucous plaques usually present over shins. Wickham striae, mucos membrane, and nail involvement seen often present	Compact orthokeratosis, wedge-shaped hypergranulosis, irregular acanthosis, vacuolar degeneration of basal layer, band-like dermal lymphocytic infiltrate
Lichen simplex chronicus[14]	Severely pruritic, symmetrical hyperpigmented, lichenified plaques most commonly over shins	Hyperkeratosis interspersed with parakeratosis, acanthosis with irregular elongation of the rete ridges, wedge-shaped hypergranulosis, slight spongiosis, and sparse perivascular lymphocytic infiltrate in dermis
Chronic eczema[15]	Ill-defined pruritic scaly plaques mostly over acral regions. Unilateral and sometimes lichenified	Hyperkeratosis, parakeratosis, wedge-shaped hypergranulosis, focal spongiosis, acanthosis. Sparse inflammatory infiltrate in dermis
Acral acanthosis nigricans[16]	Hyperpigmented, thickened, velvety plaques over dorsum of hands and feet	Hyperkeratosis, papillomatosis, irregular acanthosis, slight hyperpigmentation of basal layer, upward finger-like projection of dermal papillae, horn pseudocysts can be seen
Necrolytic acral erythema[9]	Well-circumscribed, symmetrical dusky to violaceous plaques with or without scaling with a rim of erythema over acral areas. Sometimes vesiculation or bulla formation can be seen	Hyperkeratosis with psoriasiform hyperplasia, necrotic keratinocyte with vacuolar degeneration, parakeratosis, papillomatosis, focal hypergranulosis, pigment incontinence, inflammatory cells in papillary dermis
Acquired zinc deficiency[10]	Acral, periorificial, and ano-genital erythematous scaly sharply demarcated patches, alopecia, paronychia, and transverse ridging of nails	Necrolysis, confluent parakeratosis, hypogranulosis, psoriasiform hyperplasia, vacuolization, and ballooning degeneration
Zinc-responsive acral hyperkeratosis	Bilaterally symmetrical well demarcated hyperpigmented scaly plaques over dorsum of hands and feet	Hyperkeratosis, focal parakeratosis, acanthosis with normal granular layer, and intact basal cell layer. Sparse perivascular mononuclear infiltrate of lymphocytes in the dermis