LAUSR

(BLAISE) presenting as a paraneoplastic phenomenon Dear Editor, Blaschko Linear Acquired Inflammatory Skin Eruption (BLAISE) is a unifying term encompassing the spectrum of inflammatory dermatoses, which can manifest along the lines of Blaschko. First coined by Taieb et al. in 1991, the acronym is of increasing relevance as recent studies have highlighted that adult blaschkitis and lichen striatus share overlapping clinical and histopathological features. It also advantageously incorporates entities less commonly seen in a blaschkoid distribution, such as lichen planus, where differentiation may prove difficult. We report a 79-year-old woman who presented with a multilinear papulosquamous eruption of 6 weeks’ duration. Examination revealed a strikingly symmetrical distribution along the lines of Blaschko involving bilateral upper limbs and trunk (Fig. 1). Her medical history included atopic dermatitis treated with methotrexate 15 mg orally (weekly) and bilateral mastectomy for breast cancer 8 years prior. Concurrent with her rash, she noted macroscopic hematuria and unintentional weight loss. Subsequent investigations revealed an underlying stage II transitional cell carcinoma of the bladder. Skin biopsy showed scattered apoptotic keratinocytes throughout the epidermis, basal layer vacuolization, and a sparse interstitial and perivascular lymphohistiocytic inflammatory infiltrate in the superficial dermis (Fig. 1). With the exception of a subcorneal pustule, these were compatible with previously reported histopathological features of BLAISE. Due to its asymptomatic nature, application of emollient only was recommended. Complete resolution followed in 4 weeks, during which time the bladder wall tumor had been resected. To our knowledge, this is the first reported case of BLAISE presenting as a paraneoplastic phenomenon. The history fulfills the first two criteria of Curth’s postulates in establishing the association between a cutaneous manifestation and internal malignancy; namely that the blaschkoid rash and bladder wall tumor manifesting as hematuria were of concurrent onset and that the two followed parallel courses. The pathogenesis of BLAISE remains poorly understood. It is hypothesized to represent a T-cell mediated autoimmune reaction, directed against keratinocytes along the lines of Blaschko that harbor hidden genetic mosaicism. Acquired stimuli including infections, drugs, and trauma may trigger either expression of cutaneous antigenic mosaicism or loss of immune tolerance. Oncoproteins expressed by tumor cells can similarly trigger an immune response, akin to other paraneoplastic conditions such as dermatomyositis. Previously documented associations between bladder cancers and paraneoplastic dermatomyositis lends further support to our observation. In light of this novel association between BLAISE and underlying visceral malignancy, we propose that age-appropriate malignancy screen coupled with full systems enquiry should be adopted in the evaluation of adult patients presenting with BLAISE.