have indicated no significant interest with commercial supporters.C utaneous horns are relatively uncommon lesions in clinical practice. They arise as a variably sized protrusion of keratotic, cohesive material organized in the shape of a conical horn, often located on the face or in sun-exposed areas. Their variable origin from benign or malignant/premalignant conditions is a known fact as well as the need in performing a histopathologic study of each excised lesion to determine the exact nature of the disorder at the base of the lesion. The most common epidermal conditions from which cutaneous horns arise include seborrheic keratosis, viral wart, solar keratosis, Bowen's disease, and squamous cell carcinoma. 1 Approximately one-half of cutaneous horns are derived from benign lesions, 23% to 37% from actinic keratoses, and 16% to 20% from definitely malignant lesions. 2 It has been said that large/ giant cutaneous horns are commonly derived from a malignant base; 3,4 however, large lesions have also been associated with verruca vulgaris. 2 We are presenting an unpreviously recognized form of verrucous malignant melanoma arising as a cutaneous horn.
Case ReportA 29-year-old woman presented with a 1-year history of an asymptomatic growth on her left leg. In the past months the slowly enlarging mass became painful on hooking with her stockings, bleeding occasionally.Physical examination revealed a firm, hyperkeratotic, hyperpigmented, conical protrusion surrounded by normal skin. No ulceration was clinically observed. The rest of the physical examination was unremarkable. The lesion was excised and submitted to study with the clinical diagnosis of cutaneous horn.On gross examination, histopathologic study revealed a conical, hyperkeratotic mass of 1.75 Â 2.5 cm (Figure 1). Microscopic examination showed an ulcerated melanocytic neoplasia distinctive of nodular malignant melanoma. It was composed of nests of epithelioid cells with large, hyperchromatic nuclei, prominent nucleolus, and atypical mitotic activity. The nests were distributed at the dermoepidermal union and superficial epidermal stratum, also infiltrating the papillary and reticular dermis with a depth of 7 mm (Figure 2). There was no pagetoid scatter of single melanocytes above the dermoepidermal junction. The atypical mitotic activity was present at both epidermal and dermal levels ( Figure 3). The lesion was asymmetrical, showing an accentuated verrucous, orthoparakeratotic epidermal hyperplasia without hypergranulosis, with elongated rete ridges and prominent dermal papillomatosis. A slight bandlike inflammatory lymphocytic infiltrate with some plasma cells was distributed in the dermis. Some nests of melanocytes were observed in the vicinity of dermal and lymphatic vessels. Melanin pigment was