Introduction. Pachydermodactyly is a rare disease with asymptomatic swelling of proximal interphalangeal joints. This disorder should be considered in the differential diagnosis of juvenile idiopathic arthritis or rheumatoid arthritis. However, pachydermodactyly is not well recognized by many orthopaedic surgeons and rheumatologists. Case Presentation. We report herein a case of a 13-year-old girl with pachydermodactyly. She presented to our clinic with symmetrical swelling of digits II through V without functional loss for the last 4 years. X-ray examination demonstrated no bone or joint destruction and magnetic resonance images showed only thickened skin tissues. No inflammatory signs were seen with laboratory blood tests. We reached a diagnosis of pachydermodactyly by exclusion. We had administered tranilast to her for 6 months and her symptom slightly improved. Conclusion. It is important to recognize pachydermodactyly and be able to differentiate it from other causes of PIP joint swelling such as rheumatoid arthritis, although pachydermodactyly is rare and benign. Physicians including orthopaedists and rheumatologists should make a prompt diagnosis to avoid unnecessary investigations and prevent the patient from receiving inappropriate treatment with steroids or cytotoxic agents. On the other hand, tranilast might be an effective drug to pachydermodactyly.