Dermatofibroma

Definition

• Common benign cutaneous neoplasm
• Fibroblasts of the dermis forming a nodule under the epidermis

Incidence

• Relatively common, F > M (4:1)
• Usually occurs in young adults / 20s

Aetiology

• Unknown, may have a genetic component

Clinical

• Mostly on extremities (mostly lower legs)
• Usually asymptomatic
• May have pruritus/tenderness
• 0.5-1cm hard nodule overlying skin can be many colours
• Nodule may feel like a frozen pea or a small pebble fixed to skin surface, freely mobile over subcutaneous tissue
• Characteristic tethering of the overlying epidermis with manual lateral compression of the skin = Dimple Sign
• Most are solitary
• Multiple seen in
  • SLE, HIV, Leukaemia

Pathology

• Clonal cell growth
• Proliferation of fibroblasts ? reactive ? neoplastic
• Histology: Tumour is in the mid-dermis: Whirling fascicles of Spindle Cells
• (DDx: Dermatofibrosarcoma Protuberans)

Investigations

• Excision Bx if suspicious / atypical

Management

• Removal of the tumour is not necessary, unless diagnostic uncertainty exists or troubling Sx are present – excised with subcutaneous tissue

Prognosis / Natural Hx:

• Slow growth
• Most lesions remain static indefinitely