Perforating lichen nitidus in the setting of atopic dermatitis.

Perforating lichen nitidus is a rare subtype of lichen nitidus, with approximately 11 cases reported worldwide. Lesions typically present in young male patients at sites prone to mechanical irritation, including the hands, feet, forearms, elbows, and knees. Classic histopathologic features of perforating lichen nitidus show a lymphohistiocytic infiltrate within the papillary dermis between hyperplastic rete ridges with transepidermal elimination of dermal contents. Very few cases are reported in the literature of lichen nitidus and its association with atopic dermatitis. This is the first case describing perforating lichen nitidus in a patient with a history of atopic dermatitis being treated with dupilumab injections. Lesions of perforating lichen nitidus worsened with successful treatment of atopic dermatitis. These findings suggest a unique pathophysiology of perforating lichen nitidus lesions.

An unusual variant of lichen nitidus: Generalized follicular spinous with perifollicular granulomas.

Several unusual variants of lichen nitidus are described in the literature. Spinous follicular lichen nitidus with perifollicular granulomas is one such variant characterized by generalized follicular as well as nonfollicular keratotic papules, which show perifollicular granulomas on histopathology as well as a lichenoid granulomatous tissue reaction typical of lichen nitidus. Owing to its atypical clinical and histopathologic manifestations, it raises several clinical possibilities and can be a diagnostic challenge. We report this rare variant of lichen nitidus in a 19-year-old female, and discuss its clinical and histopathological differential diagnosis.

Dermatoscopic features of lichen nitidus.

Dermatoscopy is a noninvasive, painless, and easily repeatable technique that reveals interesting and characteristic features associated with various cutaneous conditions. Lichen nitidus is a rare dermatosis of childhood. We describe the dermatoscopic features in 8 cases of lichen nitidus, which can aid noninvasive diagnosis. The report serves to emphasize the need for examining these lesions using both polarized and nonpolarized modes.

Disseminated Granulomatous Perifollicular Dermatosis With Comedones: A Follicular Variant of Lichen Nitidus or a New Entity?

The presence of acquired generalized keratotic follicular papules and comedones developing in adulthood constitute an uncommon clinical situation. Although this clinical presentation has been described in several noninflammatory, inflammatory, and neoplastic skin disorders, its association with an exclusive perifollicular epitheliod or granulomatous inflammatory reaction represents an exceedingly rare phenomenon. We report a case of a 57-year-old male patient presenting clinically numerous acquired disseminated follicular papules and comedones, showing isolated perifollicular sarcoid-like granulomatous inflammatory infiltrates at the histological examination. These lesions experienced a complete spontaneous resolution after several months. The possibility that this disseminated, epithelioid, granulomatous, perifollicular dermatosis may represent an isolated follicular variant of lichen nitidus or a previously nonreported skin disorder is discussed.

[Lichen nitidus and lichen striatus]. / Lichen nitidus und Lichen striatus.

Lichen nitidus is a rare, chronic dermatosis which occurs more often in children than in adults. It presents with tiny, monomorphous, lichenoid, mostly asymptomatic papules in regional or disseminated distribution which show a pathognomonic histological pattern. The pathogenesis is unclear; however, immunologic phenomena and genetic factors are under discussion. In rare cases, an association with other dermatoses and systemic diseases has been described. Moreover, medical treatments have been incriminated as triggers. Considering the self-limited course in mostly young patients, treatment must be thoroughly weighed. Possible therapeutic options include topical corticosteroids and calcineurin inhibitors as well as oral antihistamines, corticosteroids and narrow-band ultraviolet B phototherapy. Lichen striatus is an acquired, usually asymptomatic dermatosis occurring mostly in preschool children. The characteristic feature is the arrangement of small, flat, light red- to skin-colored papules along the lines of Blaschko. Therefore, a postzygotic mutation of epidermal progenitor cells induced to express new surface antigens by trigger factors as infections, vaccinations or trauma with consecutive immune reaction is assumed. Nail involvement of the affected limb can rarely occur. Lichen striatus usually heals without scarring within several months, so that therapies with severe side effects are obsolete. Mild topical corticosteroids or calcineurin inhibitors may be used, especially if patients exceptionally suffer from pruritus. A postinflammatory hypopigmentation can persist for months to years.

Hyperkeratotic and hypertrophic lichen nitidus.

Lichen nitidus typically presents as shiny pin-head sized papules on the trunk and extremities, often affecting children and young adults. In this prototypical form, it rarely presents a diagnostic challenge being characterized by distinctive clinical and histopathologic findings. We describe a rare variant of lichen nitidus, which we term "hyperkeratotic and hypertrophic lichen nitidus."

Perforating lichen nitidus.

Transepidermal elimination and/or perforation of the epidermis is seen in a variety of conditions but has only rarely been reported in association with lichen nitidus. We describe a case of lichen nitidus with the unique finding of epidermal perforation, a feature that made the usual straightforward diagnosis of lichen nitidus much more difficult.