Background: In a recent study, we demonstrated that lupus erythematosus (LE) tumidus (LET) is a distinct subset of cutaneous LE (CLE), which is clinically characterized by erythematous, urticaria-like, nonscarring plaques in sun-exposed areas. Objective: Our purpose was to analyze skin biopsy specimens from 80 patients with this disease and to determine whether it could be differentiated from other variants of CLE on histopathologic grounds. Methods: Skin biopsy specimens from 53 primary and 38 UVA- and/or UVB-induced lesions of 80 patients with LET were examined and compared with skin biopsy specimens from patients with discoid LE (DLE) and subacute CLE (SCLE). Results: Specimens from LET lesions showed a characteristic and diagnostic pattern of perivascular and periadnexal cellular infiltrates in the papillary and reticular dermis composed almost entirely of lymphocytes. In some cases, few scattered neutrophils were present. Furthermore, interstitial mucin deposition was observed in all specimens, as confirmed by colloidal iron staining. In contrast to discoid LE and subacute CLE lesions, epidermal atrophy or alteration at the dermoepidermal junction was not detected. Conclusion: Skin lesions of patients with LET present with specific histopathologic features, and the differences compared with subacute CLE and discoid LE further support the concept to consider LET as a separate entity of CLE. (J Am Acad Dermatol 2003;48:901-8.)