Clinical and Histopathological Characteristics of Acquired Inflammatory Blaschko-Linear Disorders

Acquired inflammatory Blaschko-linear dermatoses have not been studied extensively. Descriptive studies on segmental vitiligo have yielded insights helpful in counseling patients. Similar insights are expected from studies on other acquired inflammatory Blaschko-linear diseases.

Consecutive patients with an acquired inflammatory Blaschko-linear disease presenting to the dermatology outpatient department of the study center were recruited in a case series. Detailed history and examination, clinical photographs, and histopathological findings were recorded and analyzed. Features were compared between linear and generalized forms to look for any differences.

Out of 99 patients, linear lichen planus (n = 47), linear morphea (n = 31), and lichen striatus (n = 9) were observed most commonly. Skin lesions were present in multiple lines in 52 (52.5%). In 12 (12.1%), more than one anatomical site was involved. In 10 (10.1%), two different Blaschko-linear diseases were seen, and in 3 (3.1%) both diseases occurred in the same/adjacent segments. The disease extended from one or both ends in 64 (88.9%). Nineteen (19.2%) had both linear and generalized disease, with linear lesions being more severe than the generalized lesions (P = 0.038133). Some (18/47, 38.3%) linear lichen planus cases showed prominent atrophy since the onset and formed a distinct subset, predominantly over the head and neck site (P < 0.00001). Histopathology of linear lichen planus differed from controls with generalized lesions in terms of having deeper infiltrate (P = 0.000124), and multi-focal, rather than confluent, lichenoid infiltrates. Atrophy was noted from the onset in 13/31 (41.9%) cases of linear morphea.

Limitations include cross-sectional design and lack of controls with generalized nonlinear diseases.

Acquired inflammatory Blaschko-linear disorders show distinct characteristics like involvement of multiple lines and sites, directional progression, and atrophic variants. These can be used for differentiating among different Blaschko-linear diseases, monitoring progression, and counseling patients.