Causes of longitudinal nail splitting: a retrospective 56‐case series with clinical pathological correlation

Abstract

Background Split nail (SN) is a rare type of nail fragility syndrome, characterized by a longitudinal fissure involving the entire thickness of the nail plate. Longitudinal nail splitting may be caused by direct injury to the nail plate or matrix insult.Few articles have been published on the topic, most were related to the traumatic aetiology. Some case reports mention tumours and inflammatory disorders as other causes. Objectives and MethodsThe aim of this retrospective study was to analyse the clinical and histopathological features of 56 SN collected at the nail consultation of the dermatology department at Saint Pierre University Hospital in Brussels, between 1997 and 2019.Results Fifty-six patients were included (34 women and 22 men) with median age of 44.2 years. The fingernails were 3.2 times more frequently affected than toenails, especially the thumb. The most frequent aetiologies were tumours (45.6%), inflammatory diseases (26.3%) and traumas (19.3%). Congenital (5.3%) and systemic disorders (3.5%) were rarer causes. Histopathological slide review confirmed that alteration of the nail matrix integrity causes split nail, resulting either from matrix stretching by an underlying tumour or from impairment of the keratinization process by inflammatory diseases, melanocytic tumours and Bowen's disease. ConclusionsThis study is the largest case series of longitudinal nail splitting to date. It is the first to gather nail disorders causing SN with their clinical pathological correlation. The most common causes are traumatisms, tumours and inflammatory disorders. Congenital and systemic disorders are rarer. Tumours are responsible for half of the cases from which one third are malignant, mainly melanoma. When facing a monodactylic SN, benign as well as malignant tumours should be ruled out before concluding to traumatic aetiology.

Looking Beyond the Hutchinson Sign: A Retrospective Study of Clinical Factors Indicating the Presence and Invasiveness of Nail Unit Melanoma in Patients With Longitudinal Melanonychia

“…21 On the other hand, alteration of the proximal or the entire matrix leads to the production of a thin nail plate that easily breaks even with daily life activities, resulting in nail splitting. 22 Considering that NUM arises from abnormal nail matrix melanocytes, it is reasonable to associate nail splitting to locally advanced melanoma, which is an association supported by previous studies. 8,22 Therefore, the presence of nail splitting in patients with LM may indicate destruction of a large part of the nail matrix, which suggests NUM rather than benign LM and IM rather than MIS.…”

“…22 Considering that NUM arises from abnormal nail matrix melanocytes, it is reasonable to associate nail splitting to locally advanced melanoma, which is an association supported by previous studies. 8,22 Therefore, the presence of nail splitting in patients with LM may indicate destruction of a large part of the nail matrix, which suggests NUM rather than benign LM and IM rather than MIS.…”