Clincial presentation
A 29-year-old man presented on his left arm with a brownish-pink, 0.5 cm-diameter, hard, asymptomatic papule surmounted by a hyperkeratotic cone that had been growing in the central area for about 1 year (Fig 1).
Fig 1.
Pinkish-brownish left arm papule surmounted centrally by a hyperkeratotic cone.
Dermoscopic appearance
Dermoscopy revealed the presence of a central yellowish conical projection, surrounded by a whitish-pink area with dotted vessels, which in turn was surrounded by a brownish peripheral network (Fig 2).
Fig 2.
Dermoscopic features including whitish-pink area with dotted vessels surrounded by a brownish peripheral network and surmounted by a yellowish cone.
Histological diagnosis
Histologic examination showed hyperplastic and hyperkeratotic epidermis in the central area, with circumscribed dermal proliferation of CD10+ fusiform cells, compatible with the diagnosis of dermatofibroma surmounted by cutaneous horn in the central region.
Keypoints.
Dermatofibroma is a benign skin tumor characterized by proliferation of histiocytes or spindle cells in the dermis.1 Generally, it requires no treatment. Sometimes doubtful forms should be distinguished from other skin cancers such as melanoma, basal cell carcinoma, and squamous cell carcinoma.2 Dermatofibroma may also rarely be associated with an overlying cutaneous horn, as in the only case reported in literature described by Nam et al.1 It is a hyperkeratotic protrusion, the pathogenesis of which is not fully elucidated, typical of the elderly age and which may be associated with malignant transformation into squamous cell carcinoma.1 In the case described, the lesion was excised for this risk and because the horn masked the dermoscopic features of the lesion, which could also appear as a Bowen disease. The aim of the report is to describe a rare case of a young patient with cutaneous horn arising on dermatofibroma and emphasize when its excision is indicated.
Conflicts of interest
None disclosed.
Footnotes
Funding sources: None.
Patient consent: The authors obtained written consent from patients for their photographs and medical information to be published in print and online and with the understanding that this information may be publicly available. Patient consent forms were not provided to the journal but are retained by the authors.
IRB approval status: Not applicable.
References
- 1.Nam K.H., Lee S.K., Lee I.J., Park J., Yun S.K. Cutaneous horn arising from angiokeratoma associated with underlying dermatofibroma. Indian J Dermatol. 2023;68(4):463–464. doi: 10.4103/ijd.ijd_644_21. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 2.Smith H., Wernham A., Patel A. When to suspect a non-melanoma skin cancer. BMJ. 2020;368 doi: 10.1136/bmj.m692. [DOI] [PubMed] [Google Scholar]