Onychocytic matricoma as an underrecognized benign mimicker of subungual malignant melanoma and Bowen's disease

Longitudinal subungual acanthoma: one denomination for various clinical presentations

“…Others were characterized by a longitudinal streak extending to the distal lunula with localized nail plate thickening similar to our first and second cases . The entire nail plate can even be affected by brown pigmentation and irregular thickening which may mimic Bowen's disease or melanoma …”

“…Subsequently, this name of onychocytic matricoma was used in other publications . Some of them presented with a leucoxanthonychia and nail thickening, as in our third case .…”

“…When the lesion presents as a longitudinal melanonychia, a melanocytic proliferation and especially a melanoma if the whole nail plate is affected may be discussed but the association with localized nail plate thickening will help to exclude a diagnosis of acanthoma.…”

Pachyonychia of the toenail in a child

“…The differential diagnosis includes: OM [ 2 ] , a foreign body [ 4 ] , a malignant tumor of the nail unit [ 5 ] , severe nail psoriasis with onychodystrophy [ 6 ] , or onychomycosis alone [ 7,8 ] . In our case, onychomycosis was considered as a superinfection of an underlying nail tumor, which was suspected on the basis of the anamnestic, clinical and dermatoscopic fi ndings.…”

“…To our knowledge, dermatoscopy of OCM has only been described in pigmented cases [ 4,5 ] . In our patient, high-magnifi cation dermatoscopy led us to suspect OM at fi rst, due to the yellow discoloration of the nail plate with longitudinal lines and the perforated "honeycomb" appearance of its distal margin [ 11 ] ; the fi nal diagnosis of OCM was based on histopathology.…”