Cutaneous hornhttps://en.wikipedia.org/wiki/Cutaneous_horn
Cutaneous horn are unusual keratinous tumors with the appearance of horns, or sometimes of wood or coral. They are usually small and localized but can, in very rare cases, be much larger. They can be malignant or premalignant.

Malignancy is present in up to 20% of cases, with squamous-cell carcinoma being the most common type. The incidence of squamous-cell carcinoma is to 37% when the lesion is present on the penis.

○ Diagnosis and Treatment
#Skin biopsy
  • A biopsy is necessary as skin cancer, such as squamous cell carcinoma, is often present.
  • Typical size and location (ear).
References Cutaneous Horn 33085427 
NIH
A cutaneous horn is usually evident upon physical examination and can be described as a white or yellow exophytic protrusion in the shape of an animal horn. Cutaneous horns are now widely accepted as a reactive cutaneous growth caused by a variety of benign, premalignant, or malignant primary processes. Actinic keratoses are the most common premalignant primary cause of cutaneous horn, while squamous cell carcinoma (SCC) is the most common malignant cause.
 Cutaneous horn: a potentially malignant entity 20043059
Cutaneous horn is a dense, cone-shaped growth with thickened skin, often resembling an animal's horn. It's a term describing an unusual buildup of hardened skin cells, rather than a specific disease. Cutaneous horns can develop alongside various benign, pre-cancerous, or cancerous skin conditions. A key concern is distinguishing between a thickened sun-damaged skin spot and a potentially cancerous growth like squamous cell carcinoma. Another culprit is keratoacanthoma, which presents as a raised, nail-like tumor. Treatment typically involves removing the horn and examining it under a microscope to check for cancer.