Unusual Interface Dermatoses Distributed Along Blaschko's Lines in Adult Patients

Linear dermatoses are unusual entities whose distribution reflects cutaneous mosaicism, even when they occur in adult life. Adult blaschkitis (AB) and lichen striatus (LS) always follow this peculiar distribution. Although usually referred to as distinct entities, the clinical and histopathological presentation of lichen striatus in adults may be similar to those of adult blaschkitis. Moreover, some cases with overlapping features between lichen striatus and linear lichen planus have been published, making precise diagnosis very difficult. Recently, the concept of a wide spectrum of blaschkolinear dermatoses with AB and LS located somewhere within it has been proposed but it has not gained general recognition. We report three cases of dermatoses following the lines of Blaschko in adults (two women and one male, ages 35, 50 and 56, respectively). They involved the upper extremity in two cases and the lower in the third. Clinically, they were interpreted as linear lichen planus or blaschkitis but, histopathologically, they showed features consistent with lichen striatus. Lesions subsided with topic steroids and/or tacrolimus ointment, they are an example of the significant overlapping between these three entities, demonstrating that they may exist on a spectrum both clinically and histopathologically and clinico-pathologic correlation is essential to achieve an accurate final diagnosis. A detailed review of previously published cases has also been made.