Blaschkolinear Acquired Inflammatory Skin Eruption (BLAISE): Case Report of a Young Man Whose Dermatosis had Features of Lichen Striatus and Blaschkitis.

Cutaneous conditions can follow Blaschko's lines on the skin, which are thought to reflect patterns of cell migration and clonal expansion during embryonic development of the epidermis. These diseases are hypothesized to be caused by genetic mosaicism resulting from processes such as lyonization or somatic postzygotic mutation. Lichen striatus and blaschkitis are two such acquired inflammatory skin disorders that are distinguished in the literature by age of onset, location, and histopathological features. Lichen striatus is typically observed on the extremities of children and is characterized by lichenoid papules that appear in a linear distribution along Blaschko's lines. Microscopic examination typically shows spongiosis, as well as lichenoid and periadnexal inflammation. Blaschkitis more commonly occurs in adults and frequently involves the truncal areas, including the chest and abdomen. Microscopic examination typically shows spongiotic dermatitis. We describe a young man with a linear eruption extending from the flexor aspect of his right wrist to his central chest, which has features of both lichen striatus and blaschkitis. Both lichen striatus and blaschkitis are self-limited diseases that may resolve within months. It has been suggested that lichen striatus and blaschkitis are not separate entities, but rather the two endpoints within the spectrum of blaschkolinear acquired inflammatory skin eruption (BLAISE). The overlapping features of lichen striatus and blaschkitis in our patient demonstrate the spectrum of clinical and pathologic features in patients with BLAISE.