Dermoscopy of the Nail

Question 1

What is Melanonychia and what are 11 possible causes?

Answer 1

Melanonychia is a band of brown-black discolouration due to melanin in a nail plate. It may be transverse or longitudinal, single or multiple, due to melanocyte activation or tumours either benign or malignant.

Possible causes:

1-Exogenous pigment -silver nitrate, tobacco, henna

2-Ethnic pigmentation

3-Inflammatory skin disease (psoriasis, lichen planus)

4-Trauma (nail biting, shoe friction, radiotherapy)

5-Infections (paronychia, onychomycosis especially when due to moulds; pigmentation is nonmelanocytic)

6-Drug reactions (hydroxyurea, antiretrovirals, antimalarials, metals)

7-Endocrine disease (Addison disease, Cushing syndrome)

8-Nonmelanocytic tumours (SCC in situ, onychomatricoma, myxoid cyst, viral warts)

9-Melanocytic naevus of nail matrix

10-Lentigo / benign melanocytic hyperplasia

11-Malignant melanoma

Question 2

Name the cause of the nail pigmentation/discolouration

Answer 2

Pseudomonas infection

Question 3

Name the cause of the nail pigmentation/discolouration

Answer 3

Pseudomonas infection

Question 4

Name the cause of the nail pigmentation/discolouration

Answer 4

Pigmentation due to trauma

Question 5

Name the anatomical markers of the nail

Answer 5

Question 6

Name the cause of the nail pigmentation/discolouration

Answer 6

Exogenous Pigmentation

Question 7

What are some general tips for dermatoscopic examination of the nail? What information can be gleaned from examining the end of the nail?

Answer 7

1-Apply gel to the nail.

2-Examine the nail plate from above as well as end-on (the free edge of the nail).

Seen end-on:

• Pigment in the top of the nail plate has its origin in the proximal matrix
• Pigment at the bottom of the nail plate has its origin in the distal matrix or nail bed.

Question 8

What do the below clinical presentations mean in the nail?

1-Blood spots

2- Light to dark brown background colour or bands

3-Regular thin lines

4-Irregular lines

5-Grey background and thin grey lines

6-Micro-Hutchinson sign

Answer 8

1-Subungual haemorrhage

2-Melanocytic Naevus

3-Melanocytic hyperplasia

4-Melanoma

5-Epithelial melanin

6-(cuticular pigmentation not easily seen by naked eye examination) Highly suggestive of melanoma, however can also be congenital naevus.

Question 9

Name this nail lesion?

Answer 9

Melanocytic Naevus

Question 10

Name this nail lesion

Answer 10

Melanocytic Naevus

Question 11

Name this nail lesion

Answer 11

Melanocytic Naevus

Question 12

Name this nail lesion and the associated nail sign

Answer 12

Melanocytic Naevus and Pseudo-Hutchison sign

Question 13

Name this nail lesion

Answer 13

Melanocytic Naevus

Question 14

Melanocytic naevus of the nail apparatus is characterised by:

Answer 14

1-Regular parallel lines

2-Brown background

3-Granular inclusions

NB: Dark pigmented bands may result in the pseudo-Hutchinson sign, in which the pigmentation is visible through the transparent nail fold.

Question 15

Name this type of Melanonychia, what can cause it and what it is characterised by:

Answer 15

Epithelial melanin

Causes include: Ethnic-type pigmentation, lentigo, and drug-induced pigmentation.

Characterised by:

Homogeneous longitudinal thin grey lines

Light brown to dark grey background colour.

-Epithelial melanin may affect multiple nails, particularly in individuals with skin phototype 5 or 6. They are more often observed on fingernails than toenails.

NB: May be seen as part of Laugier-Hunziker syndrome or Peutz-Jeghers syndrome.

Question 16

Dermoscopic features of nail matrix melanoma include (5)

Answer 16

1-Longitudinal brown to black parallel lines with irregular colouration, spacing, or thickness

2-Disruption of parallelism, e.g. pigmentation increases in width proximally

3-Brown background

4-Hutchinson sign: pigmentation of nail fold

5-Nail plate fissuring or destruction

Question 17

Name this non-pigmented nail lesion

Answer 17

Glomus Tumour.

A rare neoplasm arising from the glomus body and mainly found under the nail, on the fingertip or in the foot.

Question 18

Name this non-pigmented nail lesion

Answer 18

Amelanotic Melanoma

Question 19

Name this non-pigmented nail lesion

Answer 19

Keratoacanthoma

Question 20

Name this non-pigmented nail lesion

Answer 20

SCC in situ

Question 21

Name 5 non-pigmented nail lesions?

Answer 21

1-Haemangioma

2-Onychomatricoma: Rare benign tumor of the nail matrix, characterized by having digitiform projections arising from the matrix. The only tumor in which the change of the nail plate has its origin in the matrix.

3-Glomus tumour

4-Invasive or in-situ SCC

5-Amelanotic melanoma

Question 22

Describe some general dermatoscopic features to look out for when examining the nail (7)

Answer 22

1-Remnants of pigmentation in melanoma

2-Atypical blood vessels in melanoma

3-Microhaemorrhage in melanoma, SCC, onychomatricoma

4-Longitudinal erythronychia (red discolouration of the nail) in haemangioma, onychomatricoma, glomus tumour

5-Yellow or white nail plate, subungual hyperkeratosis in SCC, onychomatricoma, exostosis

6-Triangular onycholysis (triangular detachment of nail from the nail bed) in SCC, glomus tumour

7-Blue spots in blue naevus, glomus tumour, melanoma