Pigmented Skin Lesions

Question 1

What is a dermatofibroma?

Answer 1

Common benign fibrous nodule that most often arises on the skin of the lower legs

Question 2

Who gets dermatofibroma?

Answer 2

Common benign fibrous nodule that most often arises on the skin of the lower legs

Question 3

What causes dermatofibromas?

Answer 3

Not clear whether reactive process or neoplasm. Lesions = proliferation of fibroblasts.

Question 4

What are the clinical features of dermatofibroma?

Answer 4

• Most often limbs, can be trunk
• Size varies from 0.5 - 1.5cm
• Firm nodules tethered to skin surface, mobile over S/C tissue
• Skin dimples on pinching lesion
• Usually asymptomatic, sometimes painful or itchy

Question 5

Dermatoscopy pattern dermatofibroma?

Answer 5

Central white area surrounded by faint pigment network

Question 6

Dermatofibroma histology?

Answer 6

Whirling fascicles of spindle cell proliferation with excess collagen deposition in the dermis

Question 7

What is neurofibromatosis?

Answer 7

Genetic disorder that affects bone, soft tissue, skin and nervous sytem

Question 8

What is NF1 characterised by?

Answer 8

• 6 or more cafe au lait spots
• multiple neurofibromas
• freckling (armpits, skin folds e.g. groin)
• Lisch nodules (tiny tumours under iris of eye)

Question 9

What are the characteristics of NF2?

Answer 9

NF2 = bilateral acoustic neurofibromatosis

• multiple tumours and lesions on the brain and spinal cord
• Tumours growing on the auditory nerves that lead to hearing loss is usually the first symptom of the disease.
• Often not apparent until the late teens or early 20’s.