We report a rare case of long-standing Hailey-Hailey disease in a Caucasian Portuguese 69-year-old woman, recently diagnosed with rheumatoid arthritis. The patient's skin lesions remained active and exudative despite topical and oral treatments with corticosteroids, tetracyclines, antifungals, and oral treatment with azathioprine. After introduction of methotrexate for rheumatoid arthritis treatment, the skin lesions regressed, with significant impact on the patient's quality of life. This case report supports the clinical evidence of methotrexate's potential role in Hailey-Hailey disease treatment.