ABSTRACT
This chapter describes the clinical features, histopathology and differential diagnosis of several diseases included in the inflammatory dermatoses, such as nail psoriasis, parakeratosis pustulosa, pityriasis rubra pilaris, eczema, alopecia areata, nail lichen planus, nail lichen striatus, lichen aureus, lichen nitidus and keratosis lichenoides chronica. Nail involvement in erythema multiforme and Stevens–Johnson syndrome (SJS) is usually seen as blisters whereas in toxic epidermal necrolysis (TEN) denudement of the surrounding skin is typical. Histologically, other necrobiotic granulomas, for example, necrobiosis lipoidica, have to be ruled out; however, there is no report of necrobiosis lipoidica in the nail apparatus. Although dermatomyositis is often diagnosed histopathologically, there are few reports on microscopic alterations of the nail. Nails are mainly involved by pemphigus vulgaris, rarely in Brazilian type of pemphigus foliaceus. Cicatricial pemphigoid involving the nail is very rare. Lichen sclerosus et atrophicans of the nail area is a very rare condition.
