Onycholemmal Horn: An Exceedingly Rare Subungual Tumor

Abstract

The onycholemmal horn is an exceedingly rare subungual tumor characterized by trichilemmal-like keratinization pattern. The only previous instance of onycholemmal horn dates back to 1983 when Haneke reported a keratotic subungual tumor clinically and histologically comparable to a trichilemmal horn. No other case of this condition has been reported so far. We present the case of a 72-year-old female patient, with a history of a slowly growing tumor originating from the nail bed epithelium of the left thumb. The lesion was surgically removed, and pathological examination was consistent with the diagnosis of an onycholemmal horn. Additionally, this study aims to elucidate the correlation between the onycholemmal and trichilemmal keratinization.

Nail Unit Squamous Cell Carcinoma with Onycholemmal Features: Case Report and Review of the Literature

“…Nevertheless, there are overlapping features with OC given the lobulated architectural growth pattern of the agminated epithelial lined cysts and the presence of abrupt onycholemmal keratinization. Onycholemmal horns are exceedingly rare, arising from the nail bed and presenting as slow-growing exophytic tumors [14] . Histologically, onycholemmal horns uniquely contain cuboidal basal cells, centrally enlarging pale staining cells, and demonstrate abrupt keratinization [15] .…”

Onycholemmal horn: A distinctive subungual tumour

“…The histopathological study showed lamellar keratin originating from the nail bed through onycholemmal keratinization. 4 These two exceptional OH cases have provided significant insights into the epidemiological, clinical and histopathological characterization of OH to date. Notably, this extremely uncommon neoformation has been reported in elderly female patients with a mean age of 67 years (ranging from 62 to 72 years) without any previous history of trauma or injury to the affected nail.…”