Disseminated eruption of ectopic sebaceous glands following Stevens-Johnson syndrome

Lid margin keratinization in Stevens-Johnson syndrome: Review of pathophysiology and histopathology

Lid margin keratinization (LMK) is a chronic ocular sequela of Stevens-Johnson syndrome (SJS), which causes lid wiper epitheliopathy and progressive ocular surface damage. The exact etiopathogenesis of LMK, however, remains elusive. This review summarizes the potential pathophysiological mechanisms of LMK and describes its histopathological features. A literature search of articles discussing the pathophysiology of LMK in SJS was performed. The possible pathophysiologic mechanisms contributing to LMK, as identified on the literature review, included loss of the muco-cutaneous junction barrier leading to epidermalization, dyskeratosis involving the meibomian gland orifices, altered lid margin microbiome, and de novo squamous metaplasia of the marginal conjunctival epithelium. Based on these mechanisms, the possible sources of keratinized epithelium at the posterior lid margin in SJS could be the adjacent anterior eyelid skin, hyperkeratinized epithelium from the meibomian gland ductal orifices, or the inflamed marginal conjunctiva. The epithelial, sub-epithelial, and stromal changes seen in keratinized posterior lid margins in SJS patients undergoing mucous membrane grafting were also investigated. The findings revealed keratinizing squamous metaplasia of the posterior lid margin accompanied by subepithelial infiltration of helper T cells predominantly on the conjunctival side. The visible meibomian gland orifices had ductal hyperkeratinization and plugging. These findings support a role for inflammation in the pathogenesis of LMK in SJS. Future research can be directed at delineating the pathways that lead to LMK by studying the changes in the lid margin microbiome, and the molecular mechanisms regulating keratinization in the conjunctiva and the meibomian gland orifices in eyes affected by SJS.

Dermatopathology update

This past year has seen a wealth of new developments in dermatopathology that appear to herald the dawning of a new era. Advances in molecular biology and the simplification of techniques have put molecular tests within reach of routine clinical practice and led to a radical change in our approach to lesions such as melanoma; in the future, the genetic characterization of these lesions will be an essential requirement for establishing diagnosis, prognosis, and therapy. Technological innovations have also reached dermatology departments: the introduction of ultrasound scans has propitiated the use of fine-needle aspiration cytology, which allows samples to be stained and studied immediately, thereby facilitating diagnosis of superficial and lymph-node lesions, and allowing staging of tumors such as melanoma. Targeted cancer therapies have led to the introduction of more sensitive and specific systems for identifying new targets, have reawakened interest in forgotten diseases such as aggressive basal cell carcinoma, and have led to dermatological reactions that, together with those caused by biologic drugs, we are just beginning to recognize. Consolidated techniques such as immunohistochemistry continue to advance with the addition of new antibodies that contribute considerably to improved diagnosis. New clinicopathologic diseases have also been described or characterized this year, including 2 new types of melanoma, and progress has been made in our knowledge of other diseases, such as primary cutaneous CD4(+) small/medium-sized pleomorphic T-cell lymphoma. These topics, together with new developments in adnexal tumors, alopecia, and other lesions, will be discussed in this review.