Tumid lupus masquerading as rosacea

A 43-year-old woman presented to our clinic in September 2023 for evaluation of a burning eruption on the face. The patient was initially seen at an outside dermatology clinic one year prior and diagnosed with rosacea which was treated with topical azelaic acid and oxymetazoline cream. The eruption progressed over the following months to include the upper chest and was associated with a burning sensation. The patient presented to our clinic for further evaluation and management. The physical examination was remarkable for erythematous, edematous plaques involving the lateral face and upper chest (Figures 1, 2, and 3). She stated that the rash worsens after sun exposure, and she denied any previously diagnosed comorbidities or family history of autoimmune disease. Differential diagnosis included tupid lupus, reticular erythematous mucinosus (REM), Jessner’s lymphocytic infiltrate, and polymorphous light eruption. A punch biopsy was completed for hematoxylin and eosin (H&E) and direct immunofluorecense (DIF), which demonstrated dense perivascular and peri-adnexal lymphocytic infiltrate with dense dermal mucin and lacking epidermal change on H&E and a positive lupus band test on DIF. Laboratory evaluation was remarkable for a positive ANA level of 1:160. The patient was diagnosed with tumid lupus and initiated on strict, sun protection, and oral hydroxychloroquine 200 mg daily with complete resolution of the eruption over the following month.

Figure 1:

Erythematous and edematous plaques on the right lateral face.

Figure 2:

Erythematous and edematous plaques on the forehead and bilateral cheeks.

Figure 3:

Erythematous and edematous plaques on the central upper chest.

Tumid lupus is a photosensitive dermatosis that classically presents as an annular urticarial plaque with central clearing on the face, upper trunk, and upper extremities [1, 2]. This lupus variant most commonly affects Caucasian, middle aged women [2]. Dysregulation of the immune system, ultraviolet radiation, and smoking have been linked to the pathogenesis of tumid lupus. Notably, there is a reduction in T-regulatory cells and epidermal Langerhans cells, accompanied by an elevation in plasmacytoid dendritic cells. Tumid lupus is also marked by an upregulation of type-1 interferon, tumor necrosis factor-alpha, and an influx of Th17 cells [3]. Tumid lupus is known to be the most photosensitive variant of lupus. When the eruption is confined to the face, as was initially observed in our patient, tumid lupus can be mistaken for facial inflammatory conditions such as rosacea. Therefore, it is crucial to gather additional clinical history and diagnostic workup to accurately discern the correct diagnosis in such instances. Clinicians should consider factors such as a lack of response to rosacea therapy or the extension of plaques into areas rarely impacted by rosacea, as these may serve as valuable clues in differential diagnosis. Tumid lupus lies on a spectrum with Jessner’s lymphocytic infiltrate and REM which are differentiated based upon unique clinicopathological findings [4]. REM is histologically identical to tumid lupus, but is morphologically distinctive and characterized by erythematous macules and papules or plaques on mid back/chest in a reticular pattern [1]. Jessner’s lymphocytic infiltrate is similar clinically, but is distinguished by a CD8+ predominant infiltrate with mucin [1]. Tumid lupus is characterized histologically by perivascular and periadnexal lymphoid aggregates in upper and lower dermis, massive dermal mucin, and lacks significant epidermal changes. The lupus band test is positive in 50 % of cases of tumid lupus [1]. Treatment of tumid lupus includes strict sun protection and antimalarials [5].