Abstract:

Objective: To characterize the cellular infiltrate and spectrum of histopathologic features in patients with tumid lupus erythematosus and discoid lupus erythematosus

Methods: A retrospective study of patients diagnosed with tumid lupus erythematosus and discoid lupus erythematosus between January 2017 and July 2023 at Thomas Jefferson University Hospital and Temple University Hospital was conducted. Histopathologic analysis of skin specimens, serologic evaluation, and a review of clinical photos was performed. The inflammatory cell infiltrate was quantitatively investigated by immunohistochemical analysis of skin specimens using multiple inflammatory cell markers (CD3, CD4, CD8, CD20, and CD138).

Preliminary Results: Skin specimens from 16 patients with tumid lupus erythematosus and 16 patients with discoid lupus erythematosus were analyzed. Smooth, indurated, pink papules, plaques or nodules, largely devoid of surface changes were distributed predominantly on sun-exposed sites in patients with tumid lupus. Erythematous papules and plaques with central atrophy and often hyperpigmented peripheries were mainly distributed on the scalp, face and ears, but also on the chest and arms of patients with discoid lupus. The mean lesion duration was weeks to months for tumid LE and 2 years for discoid lupus patients, and the average age was 50 years and 53 years old in tumid and discoid lupus patients, respectively. The female:male ratio was 4.67:1 (14 female, 3 male) and 2.4:1 (12 female, 5 male) for tumid and discoid lupus, respectively. Racial distribution was 6 black, 7 white, and 3 Hispanic among the patients with tumid lupus, and 15 black, 1 Asian, and 1 Hispanic among the patients with discoid lupus. Histopathologic findings in skin specimens from patients with tumid lupus included a superficial and deep, perivascular, and frequently periadnexal infiltrate of lymphocytes, mucin deposition throughout the dermis, and focal vacuolar interface changes with necrotic keratinocytes in 56.3% (9/16) of cases. Among the tumid lupus cases, 25% (4/16) of cases involved the subcutis and 1 case had rare eosinophils. Immunohistochemical findings demonstrated a large increase in CD20-staining B cells in discoid lupus (avg=60.9%; range 41% - 92.7%), compared to tumid lupus (avg=22.1%; range 2.4% - 40.1%; p=0.00019). Among the patients with tumid lupus, 25% (4/16) had positive ANA titers, 25% (4/16) had positive SSA titers, 12.5% (2/16) had positive SSB titers, and 12.5% (2/16) of patients had concomitant systemic lupus erythematosus (SLE). There was one patient with tumid lupus who also had adult Still’s disease. Among the patients with discoid lupus, 18.8% (3/16) had positive ANA titers, 12.5% (2/16) had positive SSA titers, and 12.5% (2/16) patients had concomitant SLE. A history of smoking was highly prevalent among patients with tumid lupus [87.5% were smokers (6/16) or former smokers (8/16)] as compared to discoid lupus [43.8% were smokers (6/16 cases) or former smokers (1/16 cases)].

Preliminary Conclusions: Focal vacuolar interface changes are more commonly observed in skin specimens of patients with tumid lupus erythematosus than previously described in literature—56.3% (9/16) in our study, compared to 20% (3/15) which was previously reported. Concomitant SLE appears to be comparable to or slightly higher than previously reported in patients with tumid lupus, with 12.5% (2/16) of patients in our study.  Smoking is highly prevalent in patients with tumid lupus, 87.5% (14/16) in our study. Discoid lupus has a prominent B-cell infiltrate, consistent with previous reports, as compared to tumid lupus.