The curled sebaceous horn.

The mysterious sebaceous horn (devil's horn) is a historically perplexing phenomenon of unknown etiology. It classically occurs on the sun-exposed areas of the face and hands and consists of a keratin mound with a benign base in most cases and squamous cell carcinoma occurring in about 20% of patients.

Case Report

An 85‐year‐old lady presented with a growth on her face resembling an earring at first glance since it was located close to but not on the right ear itself. On closer inspection and to my surprise, it was a coiled sebaceous horn that had been there and growing slowly for most of her life. She gave a history of it beginning as a dot on the cheek when she was a young girl and due to her shy and conservative personality opted not to see a physician about it until recently when her grandchildren encouraged her along our way. She gave no history of pain, infection, swelling or discharge. It did not bother her in any way except for its appearance. On excision the base was completely removed with the sebaceous horn and the skin neatly closed. Histology revealed a benign base with normal skin and a sebaceous horn.

Discussion

One of the first descriptions of the sebaceous horn was documented in detail by a surgeon by the name Erasmas Wilson at the St. Pancras Infirmary, London in 1844 1. He described the peculiar pathological character of the tumors with their concentric laminated texture, epidermal tissue, and the absence of sebaceous material that would normally exist within a sebaceous cyst.

It was noted that the aperture of the follicle acquires an unusual degree of dilatation, and some of the hardened contents of the tumor are pressed through the opening. “By the addition of fresh layers from below, (the formative power having increased by the removal of superficial pressure,) the indurated mass is still further forced outwards, dilating the aperture as with a wedge, and finally increasing its size to that of the entire base of the hypertrophied follicle. The process of formation of new epithelial layers by the walls of the follicle (now become the base of the mass) will go on, unless interrupted by surgical means, for years, and in this manner those singular bodies, of which so many remarkable examples are on record, horns, are produced”.

In 1920, an opthlamologist by the name Hine described malignant change in a sebaceous horn in the proceedings of the Royal Society of Medicine 2. Since then there have been a few well‐documented descriptions of the presentation, association with Muir‐Torre Syndrome and the behavior of these unusual tumors. They are now regarded as common lesions that usually represent actinic keratoses, verrucae, seborrheic keratoses, and squamous cell carcinomas 3, 4.

Of note this particular sebaceous horn occurred in an unusual location, and had an atypical highly coiled appearance like that of the formation of the shell of a snail or mollusk. It is postulated in these organisms that the shape of the shell is attributed to growth around a coiling axis. High growth rates would normally give wide‐mouthed formations, however in this case a very slow growth rate around the coiling axis gives a highly coiled formation and would explain the shape of this particular horn.

Conflict of interest

None declared.