Erythema multiforme associated with anti-plakin antibodies: a multicentric retrospective case series.

ABSTRACT

BACKGROUND: Erythema multiforme (EM) is a muco-cutaneous inflammatory disease mainly triggered by herpes simplex virus (HSV) recurrences. Association of EM and circulating auto-antibodies against plakins (anti-PLK-Abs [EM-PLK+]) has been reported. However, little is known about this subset of EM. OBJECTIVES: We aimed to describe the clinical and immunological features and response to treatment of EM-PLK+. METHODS: We conducted a retrospective multicentric study of EM-PLK+ selected from the database of the immunological laboratory of Bichat hospital, Paris, France, from January 2009 to December 2020. Anti-PLK-Abs were detected in ≥1 immunological tests immunofluorescence assay, immunoblotting and/or ELISA. Patients with alternative diagnoses were excluded. RESULTS: We included 29 patients (16 women, median age 25 [range 2-58] years). EM-PLK+ were mostly major (EM with ≥2 mucosal involvements; n = 24, 83%) and relapsing (≥2 flares; n = 23, 79%). Cutaneous lesions were target (n = 13, 54%) and target-like lesions (n = 9, 38%) with usual topography (acral, n = 19, 79%; limbs, n = 21, 88%). Mucosal lesions affected the mouth (n = 27, 96%) and genitalia (n = 19, 68%), with a median of 2 [range 0-5] mucous membranes. EM-PLK+ were suspected as certain or possible postherpetic (EM-HSV) in 19 cases (65.5%); no triggering factors were detected in 9 (31%) patients. Desmoplakin-I/II Abs were the most frequent anti-PLK-Abs (n = 20, 69%); envoplakin and periplakin Abs were detected in 11 and 9 cases. Relapsing EM-PLK+ (n = 23) were still active (≥1 flare within 6 months) in 13 (57%) patients despite immunosuppressive therapy (n = 8, 62%). Antiviral drugs were ineffective in preventing relapse in 15/16 (94%) EM-HSV. CONCLUSION: The rationale for anti-PLK-Ab detection in EM is not elucidated. More systematic research of anti-PLK-Abs is warranted to better understand whether this association reflects humoral immune activity in a subset of EM or is fortuitous, related to an epitope spreading process. However, EM-PLK+ seems to be associated with major and relapsing subtypes, and difficult-to-treat cases.