Understanding the myriad cutaneous manifestations of conditions like systemic lupus erythematosus will aid rheumatologists in providing better care for their patients, according to a presenter at the 2020 Interdisciplinary Autoimmune Summit.
“Skin disease is not uncommon among our SLE patients,” Joseph F. Merola, MD, MMSc, director of the Center for Skin and Related Musculoskeletal Diseases and director of the Clinical Unit for Research Innovation and Trials at Brigham and Women’s Hospital in Boston, said in his presentation. “This is certainly relevant to the rheumatologist.”
Diving into the associations between skin and systemic disease, Merola focused on cutaneous lupus erythematosus (CLE) and discoid lupus erythematosus (DLE) as they pertain to SLE.
Specifically, he noted that lupus-specific lesions can be broken down into three categories: subacute lesions that can be localized or generalized; subacute lesions that can be annular or papulosquamous; or chronic lesions, with classical DLE, hypertrophic DLE or lupus profundus falling into this category.
Merola then offered data showing that arthritis is the first presenting symptom of SLE, at 49%, but that 29% of patients first present with a dermatologic manifestation. Looking at specific case patients, Merola highlighted that in DLE, the conchal bowl of the ear may be involved, while scarring alopecia, dyspigmentation and loss of pigmentation may all be present.
“One of the questions I sometimes get is how do we, as rheumatologists, think about the patient who presents with a skin rash and a biopsy report from the outside, and how do we tie that back to what I am seeing in the clinic?” he said.
To answer that question, Merola offered more concrete features for rheumatologists to look for when managing skin manifestations of connective tissue disease. Predominantly lymphocytic infiltrate topped the list, along with interface dermatitis or liquefactive change. “That is a very key pattern that we are looking for when we are thinking about skin lupus presentations,” he said.
Dermal mucin deposition is a typical feature, in addition to follicular or periadnexal infiltrate, basement membrane thickening, pigment dropout, melanin incontinence, telangiectasia or follicular plugging and hyperkeratosis.
“The features that you see here are not entirely specific to any skin lupus subset,” Merola said, noting that it is difficult even for a dermatopathologists to tell a rheumatologist what subset of disease the patient may occupy. “But they can get us in the camp of a connective tissue disease and support our clinical suspicion that this is a skin lupus variant.”
To further aid in diagnosis, Merola was part of a group that recently published a DLE classification system that may aid rheumatologists in sorting out where this disease ends and CLE, SLE or other lupus variants begin. This is critical for one important reason: overlap in symptoms of these diseases. “We like to think about these entities in isolation or in their own bucket, but skin lupus is not always so straightforward,” Merola said. “It is not so clear cut. Morphology can be overlapping.”