Abstract

Dermatofibromas (DF) are common, benign dermal spindle cell proliferations of the skin which are usually located on the lower extremities. Variants that appear unusual clinically, are in uncharacteristic locations or have atypical histopathology may be more difficult to diagnose. We report a case of a 43-year-old woman who presented with a 5x5 mm, asymptomatic round shiny pink papule on the right anterior upper arm that had been growing over the past year. Biopsy showed an appearance characteristic of dermatofibroma, with nodular spindle-shaped fibroblasts within the dermis and collagen entrapment at the periphery of the lesion, with overlying sebaceous hyperplasia. The dermatofibroma with overlying sebaceous hyperplasia is an uncommon variant. In a previous prospective cohort of 100 patients with dermatofibromas, sebaceous hyperplasia was seen in 16% of samples, and was seen most commonly on the shoulder. Occurrence of sebaceous hyperplasia where sebaceous glands are not usually prominent suggests sebaceous induction due to dermal alteration of the DF itself. DF commonly induces epidermal induction and has also been reported to induce adnexal changes. This has been theorized to be related to growth factors released by fibroblasts. DF with overlying sebaceous hyperplasia may lack the typical clinical findings including dimple sign or central white scar on dermatoscopy. Knowledge of this variant may aid in keeping dermatofibroma on differential diagnosis for a shoulder lesion with dermatoscopic features of sebaceous hyperplasia, including white yellow globules and milia-like cysts.

Financial Disclosure:
The poster abstract presenter listed below disclosed the following information about their financial interests. The ASDP Ethics Committee has reviewed these disclosures and determined that no conflicts of interest exist between financial relationships and educational content being presented.

Speaker	Company	Affiliation/Relationship
Babar Rao, MD	Calibar Imaging & Diagnostics	Consultant