Dr Senhong Lee, Clinical Trials Fellow, Skin and Cancer Foundation Inc, Carlton, Victoria, Australia; Dr Anne Howard, Dermatologist, Skin and Cancer Foundation Inc, Carlton, Victoria, Australia. DermNet NZ Editor in Chief: Adjunct A/Prof. Amanda Oakley, Dermatologist, Hamilton, New Zealand. April 2019.
Onychomatricoma is a rare, benign fibroepithelial tumour of the nail matrix .
Onychomatricoma typically affects Caucasian women with a peak incidence in the 5th decade. It is rarely observed in children .
The exact pathophysiology of onychomatricoma is unknown, although it could be precipitated by trauma [3,4].
Onychomatricoma affects a finger more often than a toe. It could involve either single or multiple digits simultaneously [2,5].
Onychomatricoma is typically slow-growing and painless. Its classic clinical features include [1,4,5]:
Rarer presentations of onychomatricoma include longitudinal melanonychia, subungual haematoma and dorsal pterygium [4,6].
Dermoscopic features of onychomatricoma include perforations in the distal portion of the nail plate, haemorrhagic striae, as well as white longitudinal grooves corresponding to the nail plate channels .
Onychomycosis may be complicated by a fungal infection (onychomycosis), so both conditions can coexist [1,5]. Delayed diagnosis and treatment are not uncommon due to unfamiliarity with onychomatricoma .
Onychomatricoma is diagnosed based on characteristic clinical features supplemented by dermoscopy, imaging and histopathology .
Imaging may be considered to guide clinical decisions before excision if the presentation is non-specific or unclear . Imaging modalities that could help with diagnosing onychomatricoma include [5,7]:
Histopathological evaluation could be performed on [1,4,5,6,7]:
Immunohistochemistry although helpful, is not routinely required in typical cases .
Common differential diagnoses of onychomatricoma include:
The definitive treatment for onychomatricoma is complete surgical excision .
Onychomatricoma typically resolves without local recurrence with complete surgical excision [2,4].
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