VARIANT_P: a 14-years multicentric follow-up study of atypical pemphigus variants in Italy

Background The clinical, epidemiological, and immunopathological profile of atypical forms of pemphigus, remains only partially known. Objectives To define the clinical, epidemiological and immunological characteristics, therapies and outcome of atypical pemphigus variants. Methods A 14-year multicenter retrospective observational study (VARIANT_P) on atypical variants of pemphigus across Italy. We collect demographic, immunopathological, and clinical data, as well as information on comorbidities and prescribed treatments. Results We enrolled 61 patients (Sex Ratio=1.77; 13 PNP, 26 PIgA, 22 PH). Median age at diagnosis and onset were 71.1 and 70.6 (PNP), 63.6 and 62.2 (PigA), 52.3 and 49.4 (PH). The average diagnostic delay was 3.0 (PNP), 9.5 (PIgA) and 2.0 months (PH). Mortality rate was 54.5% (PNP), 3.8% (PIgA) and 5.9% (PH). Cutaneous involvement was present in all cases of PIgA and PH, and in 83.3% of PNP cases. In contrast, oral mucosal involvement was observed in all PNP cases, but only in 7.7% of PigA and 21.1% of PH cases. Histology, DIF, IIF and ELISA data were variably consistent with the literature. Comorbidities included mainly solid malignancies for PNP while cardiovascular and metabolic disease were the most prevalent for PIgA and PH. Treatment mostly relied on systemic steroids and rituximab. Conclusions The VARIANT_P study contributed to data collection relatively to atypical pemphigus variants in order to promote the development of specific therapeutical guidelines in the future.