The Development of Bullous Pemphigoid in a Known Case of Psoriasis Vulgaris: a case report

Introduction: The development of Bullous pemphigoid (BP) in a patient with Psoriasis vulgaris (PV) is rare, as Bullous pemphigoid affects a different age group and its cause is not related to psoriasis. The cause of coexistence between the two diseases is still not clear and requires more reporting and review. Case Presentation: Here, we report a case of a 55-year-old woman with a 22-year history of Psoriasis vulgaris who developed itching and blisters to all four limbs around the scaly plaques of PV. Biopsy of the lesion revealed sub-epidermal bullae and an eosinophilic inflammatory infiltrate. Immunofluorescence microscopy showed linear C3 deposition at the basement membrane zone, and the condition was diagnosed as Bullous pemphigoid. Treatment in such conditions varies among reported cases, and includes methotrexate, cyclosporine, dapsone, azathioprine, and others. In this case, methotrexate was suggested but because patient could not tolerate the course of methotrexate she was started on a combination therapy of cyclosporine 100 mg PO twice daily and tetracycline PO 500 mg PO Q 6 hourly. Both conditions showed significant improvement within 4 weeks. Take-away lesson: As the cause of the concurrence is still unclear, the correct management for such cases still vary. The case report highlighted our experience to benefit dermatologists and physicians, with one therapeutic regimen that can benefit patients who cannot tolerate methotrexate due to its side effects.