Three Distinct Clinical Phenotypes of Immune Checkpoint Inhibitor-Induced Bullous Pemphigoid Predict Divergent Treatment Responses and Outcomes

Figure S1. Nodular-erosive type: Firm, dark brown to skin-colored nodules with characteristic surface ulcerations and crusting on the lower extremities. Figure S2. Therapeutic approach distribution among ICI-BP subtypes Stacked bars show the distribution of treatment strategies across ICI-BP phenotypes. The Bullous type was most commonly managed with systemic glucocorticoid (GC) monotherapy (80.0%). The Edematous erythema-bullous type more often used early combination therapy, including GC plus methotrexate (MTX) (55.6%) and GC plus MTX plus intravenous immunoglobulin (IVIG) (22.2%). The Nodular-erosive type showed an intermediate pattern, with GC monotherapy in 75.0% and GC plus MTX plus IVIG in 25.0%. Abbreviations: ICI-BP, immune checkpoint inhibitor-induced bullous pemphigoid; EEB, Edematous erythema-bullous; GC, glucocorticoid; MTX, methotrexate; IVIG, intravenous immunoglobulin. Figure S3. Initial steroid dose across phenotypes and disease groups. (A) Mean initial inpatient methylprednisolone dose (highest single-day; mg) across groups: sBP (30 mg), Bullous type (30 mg), Edematous erythema-bullous type (48 mg), and Nodular-erosive type (43 mg). (B) Comparison of mean initial inpatient methylprednisolone dose (highest single-day; mg) between ICI-BP and sBP. The Edematous erythema-bullous plus Nodular-erosive phenotypes used a higher mean initial dose than sBP (40 mg vs 30 mg; P = .045). Abbreviations: ICI-BP, immune checkpoint inhibitor-induced bullous pemphigoid; sBP, spontaneous bullous pemphigoid; EEB, Edematous erythema-bullous.