Cutaneous horn malignant melanoma.

Area of Science:

• Dermatology
• Oncology
• Pathology

Background:

• Cutaneous horns are typically associated with benign or pre-malignant epidermal proliferations.
• Malignant melanoma, a potentially aggressive skin cancer, can present in various forms.

Observation:

• A 73-year-old Japanese woman developed a cutaneous horn on her right cheek.
• The resected tumor measured 9 mm in diameter with a 14 mm protrusion, exhibiting exophytic growth and papillomatosis.
• Histopathology revealed atypical melanocytes with melanin pigments within the epidermis and dermis, directly beneath the cutaneous horn.

Findings:

• The atypical melanocytes were confined to the base of the cutaneous horn, without invasion into surrounding epidermis.
• The final diagnosis was cutaneous horn malignant melanoma, a distinct pathological entity.
• This case suggests cutaneous horn malignant melanoma may represent a specific form of verrucous melanoma.

Implications:

• Cutaneous horn malignant melanoma should be considered in the differential diagnosis of cutaneous horns.
• This entity may warrant inclusion in the spectrum of cutaneous horn-forming lesions.
• Further research is needed to understand the behavior and management of this rare melanoma variant.