Abstract: 【Abstract】 In recent years, some progress has been made in the diagnosis and treatment of nail diseases, but there are still many challenges, such as longitudinal melanonychia, rare nail unit-specific tumors and nail dystrophy. Longitudinal melanonychia may develop into melanoma. Besides, biopsy and surgery are triggering factors for acral melanoma, so it is important to decide whether to operate and how to apply operating principles in clinic. In addition, the diagnosis and treatment should be based on patients′ age, clinical evaluation results, dermoscopic findings and pathological examinations, so as to avoid missed diagnosis of malignant melanonychia and deformities from treatment of benign melanonychia as far as possible. There are few summaries of clinical manifestations and pathological features of rare nail unit-specific tumors, and their diagnosis is difficult. In particular, onychocytic carcinoma and onycholemmal carcinoma are malignant tumors with great harm, so this article focuses on the two kinds of tumors to remind clinicians to avoid missed diagnoses. The etiology of nail dystrophy is complex. Nail dystrophy caused by inflammatory diseases can be treated with topical or systemic drugs, while various nail deformities caused by genetic factors, toe deformities, improper walking posture, mechanical injuries, and chronic inflammation of the nail groove are in need of physical or surgical correction. This article gives insight into challenges and strategies for the diagnosis and treatment of the above nail diseases.

Key words: Nail diseases, Nevi and melanomas, Skin neoplasms, Nail dystrophy, Diagnosis, Therapy, Surgical procedures, operative