Table 1.
Clinical and microscopic characteristics of a series of pustular skin disorders and their clinical mimickers
| Condition | Pustule distribution | LC‐OCT features of pustules | Histologic features | ||
|---|---|---|---|---|---|
| Composition | Location, structure | Morphology | |||
| AGEP | Body, diffuse | Eosinophils (+++), neutrophils (+) | Subcorneal (+)/intraepidermal (+); multilocular (++)/confluent (+) | Irregular shape, ill‐defined border, moderately hyper‐reflective not homogenous content | Focal dyskeratosis, possible necrotic keratinocytes, focal spongiosis, mixed interstitial and mid‐dermal infiltrates, papillary dermis oedema, fibrinoid deposition |
| GPP | Body, diffuse | Neutrophils (+++), lymphocytes (+) | Subcorneal (++), unilocular (+) | Roundish shape; well‐defined borders, homogenous content | Acanthosis, suprapapillary thinning, dilated vessels in papillary dermis, mixed lymphoistiocytic dermal infiltrates + spare neutrophils |
| GPFE | Body, diffuse | Neutrophils (+++), eosinophils (+) | Intraepidermal (++)/subcorneal (+); multilocular (++)/unilocular (+) | Roundish shape, well‐defined borders, highly hyper‐reflective homogenous content | Mild focal acantholysis, exocytosis, spongiosis, papillary dermis oedema, perivascular lymphocytic infiltrate (neutrophils, eosinophils, mast cells) |
| SPD | Body, multifocal | Neutrophils (+++), eosinophils (0/+) | Subcorneal (++)/upper‐epidermal (+); unilocular (++)/confluent | Roundish shape, well‐defined borders, hyper‐reflective homogenous or not content | Normal epidermis (or rare focal acantholysis), moderate periadnexal mixed lymphoistiocytic superficial dermis infiltrates subcorneal neutrophils |
| IAD SPD‐like | Body, multifocal | Neutrophils (+++) | Sub‐corneal; multilocular | Irregular shape; ill‐defined border; not homogenous content | Mild or no acanthosis, central crusting, surrounding flaccid vesicles/pustules, cell surface iga deposits in the upper epidermis |
| IAD IEN‐like | Body, multifocal | Neutrophils (+++) | Intraepidermal unilocular (+) | Roundish shape; well‐defined borders, not homogenous content | Central crusts and peripheral ring of tiny vesico‐pustules, cell surface iga deposits in the epidermis |
| PPP | Palms and/or soles, localized | Neutrophils (+++), lymphocytes (+) | Intraepidermal (++)/subcorneal (+); multilocular (+) | Irregular/roundish shape; well‐defined borders, not homogenous content | Surrounding spongiform changes; Preserved spiral shape of the eccrine gland ducts |
| PPPP | Palms and/or soles, localized | Neutrophils (+++), lymphocytes (+) | Sub‐corneal (++); unilocular (+), confluent (++) | Roundish shape; well‐defined borders, homogenous content | Perifollicular hyperkeratosis, acanthosis, parakeratosis, suprapapillary thinning, dilated vessels in papillary dermis, mixed lymphoistiocytic dermal infiltrates, altered spiral shape of eccrine ducts |
| SS | Body, diffuse | Neutrophils (+++) | Intraepidermal (+)/junctional (+)//subepidermal (++) | Irregular shape; well‐defined borders, homogenous content | Epidermal spongiosis, dense neutrophilic infiltrate in the dermis extending to the epidermis, possible papillary oedema |
| EC | Body, localized | Eosinophils (++), neutrophils (+) | Intraepidermal/junctional | Irregular shaped papule, ill‐defined borders, non‐homogenous content | Papillary dermal oedema, mixed eosinophilic‐neutrophilic infiltrate in the upper‐mid, no signs of vasculitis |
| ACH | Hand/palms, localized | Neutrophils (+++) | Subcorneal, unilocular (+), confluent (+++) | Irregular shape; ill‐defined borders, non‐homogenous content | Adjacent spongiform pustules of Kogoj or aggregates of leukocytes, altered dermal‐epidermal junction and keratinocytes, tortuous dilated vessels in the papillary dermis |
| HW | Hand, palms localized | Necrotic keratinocytes (+++), intercellular material (++), neutrophil (+) | Subcorneal, multilobated (+), confluent | Roundish shape; well‐defined borders, non‐homogenous content | Cytoplasmatic/nuclear inclusions, acantholysis, intraepidermal blister/vacuolation in the cytoplasm along basal keratinocytes, inflammatory infiltrate is mixed, predominantly lymphocytes and neutrophils with scattered eosinophils |
ACH, Acrodermatitis continua of Hallopeau; AGEP, Acute Generalized Exanthematous Pustulosis; ECvp, Eosinophilic cellulitis vesico‐pustular variant; GPFE, Generalized pustular figurate erythema; GPP, Generalized pustular psoriasis; HW, Herpetic whitlow; IAD, Intraepidermal IgA pustulosis, variants: SPD‐like; IEN‐like, intraepidermal neutrophilic IgA dermatosis; PPP, Palmoplantar pustulosis; PPPP, Palmoplantar pustular psoriasis; SPD, Subcorneal Pustular Dermatosis; SSvp, Sweet syndrome ‐vesico‐pustular variant.