Lichen Striatus: A Model for the Histologic Spectrum of Lichenoid Reactions

Abstract

Three phases of lichenoid reactions are defined: 1) the primary phase, 2) the established phase; and 3) the senescent phase. Lichen striatus is characterized by a primary pattern that may be apparent in the epidermis, the hair follicles, and rarely the sweat glands and ducts. Focal areas of established lichenoid reaction, that are indistinguishable from lichen planus, are common. They usually are confined to the tips of elongated rete ridges. Established lichenoid patterns are occasionally present in hair follicles and are indistinguishable from those seen in lichen planopilaris. Eccrine hidradenitis, a feature of lichen striatus, is rarely seen in lichen planus. Lichen planus may be an adaptive epidermal response to a clone of aggressive lymphocytes and, as such, may be a manifestation of auto-immunity. In lichen striatus, senescent lichenoid patterns resemble those seen in lichen nitidus.

Lichen Striatus in a Girl: Successful Treatment with Pimecrolimus

“…At first, small, pink, lichenoid, and discrete papules appear and coalesce rapidly, and then extend to form a dull red, slightly-scaly, linear band between 2 mm to 2 cm in width 1,6 . The lesions, usually linear and unilateral, develop most commonly on the arms and legs, or on the neck, but may also develop on the trunk 7 .…”

“…Thus, it prevents the local activation of T-lymphocytes and both immune and inflammatory response 5 . The eruption is usually asymptomatic and recovers spontaneously within 3-6 months in most cases, but often leaves hypopigmentation especially in dark-skinned patients 1 . In our case, complications of hypopigmentation or residual lesions were not nearly observed.…”

“…LS mainly occur in children from 5 to 15 years of age. The eruption is usually asymptomatic and spontaneously recovers within 3-6 months in most cases, but often leaves hypopigmentation especially in dark-skinned patients 1 . Although the etiology of LS has not been exactly determined, it has been reported that LS is a T-cell mediated inflammatory skin disease associated with autoimmune response to mutated keratinocytic cloning 2,3 .…”

Mycosis Fungoides

“…Hyperplasia of the superficial unit produces acan thosis, (thickening of the epidermis above the level of the tips of the dermal papillae), and often results in hyper granulosis and compact hyperkera tosis. 59 Individually the cells of the superficial unit may undergo hyper trophy and show an increased cyto plasmic acidophilia. The basal unit is concerned with the replication of cells and with the maintenance of a stable interface with the papillary dermis.…”

“…59 Lichenoid responses may be cell-rich or cell-poor;@°the reaction in lichen planus is prototypical of the cell-rich lichenoid response. On the basis of comparative morphology, the ‘¿ cell-rich lichenoid response satisfies most of the morpho logic criteria, if not all, for the invasive destructive pattern of cell-mediated im munity.59…”