Misdiagnosis of psoriatic arthritis in a patient with paronychia confirmed by dermatological examination: A case report.

Abstract

Background: This case highlights the importance of a multidisciplinary approach in differentiating localized infections from systemic inflammatory diseases like psoriatic arthritis. Nail psoriasis can mimic conditions like paronychia, complicating diagnosis. We wrote this report to emphasize the need for clinical vigilance when interpreting imaging findings, especially in patients with a family history of psoriasis. Misdiagnosis can lead to unnecessary systemic treatments, underscoring the significance of dermatological input in achieving accurate diagnoses.

Case summary: A 56-year-old woman presented with redness and swelling of multiple fingertips. Her family history of psoriasis raised suspicion of psoriatic arthritis. Two rheumatologists diagnosed psoriatic arthritis based on ultrasound findings of enthesitis with a positive Doppler signal and recommended methotrexate. However, she was reluctant to initiate therapy due to potential side effects. At our Rheumatology Center, paronychia was suspected, and laboratory tests excluded systemic inflammatory arthritis. Dermatological examination confirmed paronychia, and treatment with fluconazole and ceftriaxone was initiated to address suspected mixed bacterial and fungal infections. Imaging studies, including hand and wrist X-rays, showed no erosions or other signs of psoriatic arthritis. The patient responded well to antimicrobial therapy, with resolution of symptoms. This case highlights the need for thorough clinical evaluation, careful interpretation of imaging findings, and collaboration between rheumatologists and dermatologists to avoid misdiagnosis and inappropriate treatment.

Conclusion: This case underscores the need for thorough clinical evaluation and caution in interpreting nonspecific imaging findings, especially in patients with a family history of psoriasis. While familial predisposition may raise suspicion for psoriatic arthritis, it is essential to integrate laboratory data, imaging studies, and clinical presentation, including response to targeted antimicrobial therapy. A multidisciplinary approach, involving both rheumatologists and dermatologists, is crucial to preventing misdiagnosis, ensuring appropriate treatment, and avoiding the potential harms of unwarranted therapies.