Comedogenic Lupus Erythematosus: Case Report with Dermoscopic Features of an Atypical Cutaneous Variant

Dear Editor, Comedogenic lupus (CL) is a rare form of chronic cutaneous lupus erythematosus (CCLE), which is clinically characterized by multiple erythematous papules, comedones, cysts, and acneiform scars in sun-exposed areas, and may be associated with typical discoid lupus erythematosus (DLE) lesions.[1] Although comedogenic lupus was first identified in 1972,[2] the literature on this rare variant remains limited, with only approximately 31 cases documented following a PubMed search using the terms “comedogenic,” “comedonal,” and “comedonic” lupus. A 53-year-old man presented with multiple, discrete, ill-defined nodules and plaques distributed on the forehead, central face, ears, scalp, extensor surfaces of the upper and lower limbs, and the dorsum of both hands for the past four years [Figure 1]. The patient reported mild pruritus, with a significant increase in the number of lesions over the past eight months.Figure 1: Multiple, discrete, papules, and plaques with central hyperpigmentation present on the central face with pitted scars present on the nose, cheeks, and chinIn addition, numerous pitted punctate scars were observed on the nose and malar areas. Skin-colored, succulent nodules were noted on both sides of the labio-mental crease, while white, adherent scales were present on the lesions on the limbs. The patient had no significant comorbidities and, notably, had been a chronic smoker until he quit following a flare-up of the disease. Anti-nuclear antibody (ANA) profile and rheumatoid arthritis (RA) factor were negative. Dermoscopy of the facial nodule revealed a central depression with multiple budding lobules, surrounded by yellow-brown keratin plugs and scaling [Figure 2]. Examination of the plaque on the leg showed central atrophy with peripheral hyperpigmentation, white scaling, and areas containing keratin plugs and brown globules.Figure 2: Dermoscopy of the facial nodule revealed a central depression with multiple budding lobules (); surrounded by yellow-brown keratin plugs () and scaling (). (DermLite DL3N-Polarized mode, 10×)Histopathology revealed an acanthotic and focally atrophic epidermis with follicular plugs. The basement membrane showed vacuolar degeneration. The presence of periadnexal inflammatory infiltrate and subepidermal fibrinoid degeneration was noted. The dermis exhibited a dense lichenoid and nodular infiltrate. Squamatization of the basal layer of the epidermis, along with numerous colloid bodies was present in the papillary dermis [Figure 3a and 3b]. Direct immunofluorescence was negative. Based on these findings, a diagnosis of the comedogenic variant of DLE was established.Figure 3: Histopathological examination revealed an acanthotic and focally atrophic epidermis with follicular plug (Blue Arrow, b) along with vacuolar degeneration of the basement membrane. The dermis exhibited a dense lichenoid and nodular periadnexal infiltrate composed of lymphohistiocytes and plasma cells (Yellow Arrow, b), accompanied by dilated blood vessels and melanophages in the superficial papillary dermis. (H and E, a- 10×, b- 40×)The patient was started on oral prednisolone at an initial dose of 1 mg/kg/day, hydroxychloroquine 400 mg once a day, and, topical clobetasol cream once daily along with strict sun protection measures. After four months of treatment, the patient’s lesions showed significant improvement on clinical and dermoscopic examination, leaving behind atrophic, depressed scars [Figure 4]. The patient remains on treatment and is under regular follow-up.Figure 4: After four months of treatment, lesions showed significant improvement leaving behind atrophic depressed and hollow scarsCutaneous lupus erythematosus (CLE) is an autoimmune disease that is approximately three times more common than systemic lupus erythematosus (SLE) and can be subdivided according to its clinical manifestations into acute, subacute, and chronic forms.[3] DLE is the most frequent type of CCLE, and is estimated to constitute 50 to 85% cases of CCLE.[4] Comedogenic lupus is a rare variant of CCLE, characterized by noninflammatory acneiform lesions resembling comedones, predominantly affecting seborrheic areas of the face, scalp, and retroauricular regions. It is predominately reported in women between the third and fourth decades of life, with a mean age of 38.9 years;[1] however, our case was an elderly male. While some authors suggest the condition arises due to a breakdown of the pilosebaceous units, resulting in seborrheic distribution and CD4 T-cell mediated epithelial hyperplasia, the definitive pathogenesis remains elusive.[2] Others have suggested that acneiform lesions result from the destructive process caused by mononuclear cell infiltration of the pilosebaceous units. Intrinsic to the pathology of both DLE and acne vulgaris is follicular hyperkeratosis; hence, it would not be surprising that on occasion, an exaggeration of the follicular hyperkeratosis intrinsic to DLE could translate clinically and histologically into a comedonal process.[5] Diagnosing this rare entity can be challenging as it closely mimics benign conditions, such as acne vulgaris, trichoepithelioma, Favre–Racouchot syndrome, nevus comedonicus, and milia en plaque. In our case, the presence of lesions on the trunk and extremities also led us to consider deep fungal infections, leprosy, and lupus vulgaris in the differential diagnosis. Smoking, as in other forms of the disease, seems to be an important risk factor. While generally asymptomatic, pruritus has been reported as a significant symptom in many previously reported cases. The presence of pruritus, association with smoking, and lesions on sun-exposed sites aligned our findings with those described in previous reports, aiding in distinguishing this condition from the aforementioned differential diagnoses. In various reports, the clinical presentation described is infiltrated papules and plaques, comedone-like openings, pitted scars, and few cases presented with scalp involvement in the form of atrophic plaques and scarring alopecia. In our case, dermoscopy allowed us to detect keratin plugs and atrophic changes at a microscopic level as these features were not visible to the naked eye. Skin-colored succulent nodules in our patient present on both sides of the labio-mental crease have not been previously described. Treatment of this condition can be challenging, as there is no gold-standard treatment. Photoprotection is imperative due to sun-induced exacerbation of comedones, sebum retention, and lupus onset.[2] Smoking cessation is essential to prevent exacerbation of the disease. Systemic treatment is essential, with hydroxychloroquine being the preferred drug. This report highlights the crucial role of dermoscopy in diagnosing this clinically challenging and rare variant of CCLE. The atrophic nature of the condition can lead to cosmetic disfigurement, and the potential for progression to systemic disease poses significant morbidity risks. Declaration of patient consent The authors certify that they have obtained all appropriate patient consent forms. In the form the patient has given his consent for his images and other clinical information to be reported in the journal. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest. Use of artificial intelligence (AI) The preparation of this manuscript was carried out entirely by the author without the use of artificial intelligence technologies.