Shave biopsy of the lesion confirmed a diagnosis of verruca vulgaris; although cutaneous horns can be caused by keratoacanthoma, squamous cell carcinoma, and acrochordon. A cutaneous horn presents as an elongated, hyperkeratotic, conical projection with height exceeding its diameter. The lesion has also been named cornu cutaneum and cornu humanum because of its resemblance to a horn.1,2 The base may be flat, nodular, crateriform, or plaque-like. The actual horn is comprised of compacted keratin.3
Lesions are usually asymptomatic unless traumatized, which is often unavoidable because of location and size; individual lesions may project several centimeters in length. Common sites of horns include the face, scalp, ears, neck, and dorsal surface of the hands with most lesions arising on sun-exposed areas.2
Histology of cutaneous horns is either benign, premalignant, or malignant. Examination of the base is crucial for a correct diagnosis. In a retrospective analysis of over 200 cases, 58% of lesions were either premalignant or malignant with over 93% of malignant lesions diagnosed as squamous cell carcinomas.4 In general, malignant lesions have a larger base and arise in older individuals.
Stephen Schleicher, MD, is director of the DermDox Dermatology Centers, associate professor of medicine at Geisinger Commonwealth Medical College, and clinical instructor of dermatology at Arcadia University and Kings College.
References
1. Agarwala MK, Mukhopadhyay S, Sekhar MR, Menon A, Peter CD. Solitary angiokeratoma presenting as cutaneous horn over the prepuce: a rare appearance. Indian J Dermatol. 2016;61(2):236. doi:10.4103/0019-5154.177779
2. Tian T. Cutaneous horn. DermNet. Accessed October 25, 2022. https://dermnetnz.org/topics/cutaneous-horn
3. Fatani MI, Hussain WM, Baltow B, Alsharif S. Cutaneous horn arising from an area of discoid lupus erythematosus on the scalp. BMJ Case Rep. 2014;2014:bcr2013202322. doi:10.1136/bcr-2013-202322
4. Mantese SA, Diogo PM, Rocha A, Berbert AL, Ferreira AK, Ferreira TC. Cutaneous horn: a retrospective histopathological study of 222 cases. An Bras Dermatol. 2010;85(2):157-163. doi:10.1590/s0365-05962010000200005
