Successful Treatment of Concurrent Bullous Pemphigoid and Psoriasis Vulgaris with Abrocitinib: A Case Report and Literature Review

Introduction

Bullous pemphigoid (BP) is a type 2 inflammatory skin disease characterized by blister, erythema and eczematous lesions with severe itching.¹ Psoriasis is a chronic immune-mediated skin disorder driven by type 3 inflammation, primarily involving the IL-23/Th17 axis.² The coexistence of the two conditions is rare and might impose a complicated immunological dysregulation. The pathogenesis of the concurrence of psoriasis and BP remains unknown and the treatment may be challenging. Herein, we report a patient with concurrent BP and psoriasis who was successfully treated with abrocitinib.

Case Report

A 58-year-old man presented with erythema, blisters, and pruritus on the trunk for over 2 months. He had plaque psoriasis for 40 years and alcoholic cirrhosis for 2 years. He had been treated with topical steroids without good response. Upon physical examination, tense blisters, bullae, erosion, exudation and crusting were found on the abdomen, while psoriatic lesions distributed on the upper limbs and hands (Figure 1). No mucosal involvement was found. The laboratory examination showed elevated direct bilirubin (7.6 μmol/L), lactic dehydrogenase (LDH, 280 U/L), carcino-embryonic antigen (CEA, 10.10 ng/mL) and total serum IgE level (404.52 IU/mL). The anti-BP180 autoantibody was positive. The antibodies to desmoglein 1 (Dsg1) and desmoglein 3 (Dsg3) were negative. Histopathology showed subepidermal blister and perivascular inflammatory infiltration of neutrophils, eosinophils and plasmocytes (Figure 2).

Figure 1 (A and B) Lesions of bullous pemphigoid on the abdomen before and after 32 weeks of treatment. (C and D) Psoriasis lesions on the back of the hands before and after 32 weeks of treatment.

Figure 2 (A) Histopathology of the lesions showed subepidermal blisters (HE×40). (B) Superficial perivascular and upper interstitial infiltration of lymphocytes, neutrophils, eosinophils and plasmocytes (HE×200).

The patient was diagnosed as BP associated with psoriasis vulgaris. Considering his complex health conditions (especially alcoholic cirrhosis) and potential adverse effects of systemic steroids, he was treated with abrocitinib 100 mg qod and topical halometasone cream. His pruritus improved within two days. After four weeks of treatment, his blisters and plaques improved significantly and no new blisters and crusts were observed. After 12 weeks treatment, his skin lesional mostly cleared and a complete remission of itching was found. After 24 weeks treatment, complete recovery was found for both BP and psoriatic lesions without any adverse effects. The patient remained in remission of BP and psoriasis at 8 months of follow-up.

Discussion

Bullous pemphigoid (BP) is regarded as a Th2 inflammatory skin disease characterized by the presence of tense blisters on erythematous skin with pruritus.³ The Janus Kinase/Signal Transducer and Activator of Transcription (JAK/STAT) pathway was found to be involved in type 2 inflammation signalings.⁴ Besides that, elevated expression of STAT proteins and JAK2 and JAK3 was found in BP skin lesions,⁵ which indicated that JAK inhibitor may be an effective treatment for BP. A literature review reported 17 patients with BP treated with JAK inhibitors and all of them showed good efficacy and safety profile.⁶

The coexistence of psoriasis with autoimmune bullous diseases (AIBDs), including BP, has been documented. In a retrospective analysis of 145 Japanese patients with psoriasis and AIBDs, psoriasis vulgaris was documented in 84.1% of cases and pustular psoriasis in 9% of cases, while BP was the most common AIBD (63.4%).⁷ The pathomechanisms underlying the association of BP and psoriasis are still unknown. A hypothesis of “epitope spreading” phenomenon was proposed. The tissue injury secondary to a primary inflammatory process (such as psoriasis) may induce the exposure of sequestered antigens, which evoke a secondary autoimmune disease such as BP.⁸

Abrocitinib is a high selective JAK1 inhibitor which has been approved for the treatment of atopic dermatitis (AD).⁹ The JAK/STAT pathway was involved in various inflammation including the downstream cytokine signaling pathway of Th1, Th2 and Th17 cells, which plays important roles in AD, BP and psoriasis.⁶ By downregulating the JAK/STAT pathway, JAK inhibitors have been used successfully in these diseases. Common therapeutic regimens for BP rely on systematic glucocorticoids which contradicted with the treatment of psoriasis. In recent years, several systemic JAK inhibitors have been proved to be effective in the treatment of BP coexisting with psoriasis, including upadacitinib,¹⁰ tofacitinib¹ and baricitinib.¹¹ Our study is the first report of the successful treatment of concurrent BP and psoriasis with abrocitinib, which can offer new option with good efficacy and high compliance.

Conclusion

Our study highlights the significance of JAK inhibitors in managing both psoriasis and autoimmune bullous diseases. However, this is a single case with short follow-up. Long-term efficacy and safety are still unknown. Further studies are still needed to investigate the potential mechanisms, safety and efficacy of abrocitinib for long-term use in the treatment of BP in combination with psoriasis.