Longitudinal melanonychia in an Iranian population: a study of 96 patients

BACKGROUND Longitudinal melanonychia (LM) can be a challenging sign since it may be caused by a wide variety of benign and malignant conditions. Cutaneous melanoma is the most important cause of LM. Objective: We performed this study to examine different aspects of LM in Iran, where cutaneous melanoma is rare. METHODS In this cross-sectional study, we reviewed medical records and pathology reports of a total of 96 patients presenting with LM. These patients had been visited and undergone nail biopsy in Razi Hospital, Tehran University of Medical Sciences, Tehran, Iran. Demographic, clinical, and pathological data were recorded. RESULTS The most common diagnosis was junctional nevi in 28 patients (29.2%) followed by melanoma in 19 patients (19.8%). Patients had a mean age of 42.4 years (± 19.4). The mean ages in the groups with junctional nevi and melanoma were 33.3 (± 19.5) and 51.9 (± 17.8), respectively; their difference was statistically significant (P value = 0.001). Hutchinson's sign was present in 10 patients, 9 of which had melanoma. Also, melanoma was only observed in patients presenting with a solitary nail lesion. Nails mostly affected by melanoma were middle fingers of the hands (7 patients) and thumbs (6 patients). Out of 18 patients with nail dystrophy, 13 (72.2%) were diagnosed with melanoma. LIMITATIONS Only patients who have undergone biopsy were studied. CONCLUSION Melanoma is an important cause of LM in Iranian patients and should especially be suspected in older patients who present with a solitary nail lesion on their middle finger or thumb. Other findings that direct us toward melanoma are presence of Hutchinson's sign and nail dystrophy.