Lichen striatus associated with chronic plaque psoriasis in an adult

Plasmacytoid Dendritic Cells and Type I Interferon Signature in Lichen Striatus

BACKGROUND/OBJECTIVES

In addition to several infectious and neoplastic cutaneous entities, plasmacytoid dendritic cells (pDCs) have been shown to be involved in the pathogenesis of multiple cutaneous inflammatory and autoimmune disorders, including those characterized histologically by an "interface dermatitis" pattern such as lupus or lichen planus (LP), but their role in lichen striatus (LS), which is also known to have this histologic inflammatory pattern, has never been studied. The objective of the study was to investigate the role of pDCs in LS.

METHODS

Fifteen LS patients were found in our database and were immunohistochemically tested for pDC occurrence and activity using anti-blood-derived dendritic cell antigen-2 and anti-myxovirus resistance protein A (MxA) antibodies, respectively. These individuals were also compared with 15 individuals with LP.

RESULTS

pDCs were present in all individuals with LS and LP, but they were less abundant in those with LS, although MxA (surrogate marker of local type I interferon production and thus an indirect assessment of pDC activity) was similarly intense and diffuse in all individuals with LS and LP. In addition to being part of the upper dermal inflammatory bandlike infiltrate as in LP, LS cases, unlike LP, also showed perieccrine pDCs.

CONCLUSIONS

pDCs constitute a central component of the inflammatory infiltrate in LS, suggesting a significant role in its pathogenesis. pDC distribution (perieccrine distribution) could also help in microscopically differentiating LS from LP.

Lichen striatus associated with psoriasis vulgaris treated with oral acitretin

Lichen striatus (LS) is an uncommon dermatosis of unknown etiology that presents as a continuous or interrupted linear band of pink, tan, red or skin-colored papules in a blaschkoid distribution. The lesions are generally solitary and unilateral, but unusual extensive cases with multiple and bilateral lesions have been also described. Albeit LS is typically an asymptomatic and self-limited dermatosis, it may cause a significant psychological distress in some patients, thus requiring an appropriate therapy. Topical steroid is the most commonly used treatment but it is not always effective. We report a case of LS unresponsive to topical steroid therapy associated with psoriasis vulgaris successfully treated with oral acitretin.

"Pediatric blaschkitis": expanding the spectrum of childhood acquired Blaschko-linear dermatoses

We describe two young children who developed relapsing, pruritic, papulovesicular eruptions in multiple bands along Blaschko lines on the neck, trunk, and extremities. Skin specimens in both revealed spongiotic dermatitis. This represents the first report of "blaschkitis" in children, providing further evidence that lichen striatus and blaschkitis are related acquired Blaschko-linear dermatoses that exist on a spectrum rather than as the childhood and adult form of a single disease entity. We highlight the features that differentiate blaschkitis from lichen striatus, review the potential roles of cutaneous mosaicism, environmental triggers, and background immunologic state in their pathogenesis, and discuss the spectrum of inflammatory dermatoses that can follow Blaschko lines.