Background  Subungual haemorrhages are characterized by well-circumscribed dots or blotches with a red to red–black pigmentation, but some cases can be difficult to distinguish from subungual melanoma by the naked eye alone. Dermoscopy has proven to be a useful, noninvasive tool in the diagnosis of pigmented lesions in the nail; however, few dermoscopic studies of subungual haemorrhages have been reported.

Objectives  To investigate characteristic dermoscopic patterns of subungual haemorrhages, and to find distinctive features that can differentiate them from nail-unit melanomas.

Methods  Patients with a confirmed diagnosis of either subungual haemorrhage or nail-unit melanoma at a tertiary university hospital were included in the study. Clinical features and dermoscopic patterns were evaluated.

Results  Sixty-four patients with a total of 90 lesions of subungual haemorrhage were enrolled in the study. The majority of cases (84%) showed combinations of more than one colour, while 16% had only one colour. The most common colour of the subungual haemorrhages was purple–black, in 37% of cases. A homogeneous pattern was observed in 92% of cases, globular patterns in 42% and streaks in 39%. Peripheral fading and periungual haemorrhages were found in 54% and 22% of cases, respectively. Destruction or dystrophy of the nail plate was observed in 16% of cases. In the 16 cases of nail-unit melanomas, Hutchinson sign, longitudinal irregular bands or lines, triangular shape of bands, vascular pattern, and ulcerations were found in 100%, 81%, 25%, 6% and 81% of cases, respectively. In contrast, these features were not found in subungual haemorrhages.

Conclusions  Dermoscopy provides valuable information for the diagnosis of subungual haemorrhage and aids in the differential diagnosis from nail-unit melanoma.