Bullous pemphigoid in patients who are frail: a case complicated by cerebral nocardiosis and Pneumocystis jirovecii pneumonia.

Bullous pemphigoid (BP) is the most common autoimmune blistering disorder in older patients and is typically managed with long-term immunosuppressive therapy tailored to the patient's comorbidities and overall health. Patients who are frail with concurrent haematological malignancies represent a particularly vulnerable population due to their impaired immunity and treatment-related immunosuppression. We report the case of an 85-year-old man with mantle cell lymphoma, previously treated with rituximab and ibrutinib, who developed BP confirmed by histology, direct immunofluorescence, indirect immunofluorescence and enzyme-linked immunosorbent assay. Initial disease control was achieved with systemic corticosteroids and methotrexate. Subsequently, he developed a subcutaneous thoracic nodule consistent with panniculitis, followed by cerebral nocardiosis and Pneumocystis jirovecii pneumonia. Despite successful remission of BP, his clinical course was complicated by life-threatening infections requiring prolonged hospitalization. This case highlights the delicate balance between controlling autoimmune disease and preventing severe opportunistic infections in older, frail patients with haematological malignancies. Current BP guidelines should be refined by integrating better frailty assessment, infection prophylaxis and tailored immunosuppressive strategies.