Linear lichen planus (LLP) and Lichen striatus (LS) are rare disorder that can be confused because they can share similar clinical and histopathologic features.

The purpose of this study was to evaluate the characteristic differences and common features between the two disorders histopathologically.

We reviewed the clinical records of patients who had been diagnosed as LLP or LS in our dermatology clinic during the 15-year period between 1985 and 1999. We classified twenty seven cases, which were differentiated from other possible linear dermatoses, into LLP and LS on the basis of clinical features, and then compared them histopathologically, and appreciated the characteristic differences or common features of the two disorders.

In cases diagnosed as LLP clinically, epidermal changes were mainly composed of hyperkeratosis (78%), acanthosis (78%), basal degeneration (78%), granular layer thickening (67%) and saw-toothed appearance of rete ridges (44%). In dermis, colloid bodies (78%), band-like inflammatory cell infiltration with pigmentary incontinence (78%) were strik-,ting findings. In cases with clinical features of LS, parakeratosis (50%), dyskeratotic cells scattered in the epidermis (61%) and intercellular edema (39%) were noted in the epidermis. Dermal cellular deposits were focally band-like infiltration(89%), more frequently perivascular in-filtration (83%) and often involved deep dermis (50%), hair follicles (44%) and eccrine glands (22%) in contrast to LLP.

This study presents a comparative histopathologic features of LLP and LS. Three cases of LLP with overlapping histopathologic features suggest the possibility that there may be an intermediate form between either end of a spectrum, LLP and LS.