Nail Disorders

58

Nail Disorders

• The nail matrix, which is the growth area, has proximal and distal components (Fig. 58.1).

– The proximal nail matrix forms the top (surface) of the nail plate.

– The distal nail matrix forms the underside of the nail plate; therefore, biopsies of the distal matrix are less likely to produce a deformity of the surface of the nail plate.

Fig. 58.1 Nail unit anatomy.

• Fingernails grow ~1 mm per month and are replaced every 6 months.

• Toenails grow ~0.5 mm per month and are replaced every 12 months.

• Therefore, nail plate abnormalities such as Beau’s lines that are due to insults to the nail matrix can be dated by their distance from the cuticle.

• Rx of common nail disorders is given in Table 58.1.

Table 58.1

Treatment of common nail disorders.

^* Cut back portions of detached nail plate.

Onycholysis

• Distal nail plate detachment, causing nail to look white to yellow-white (Fig. 58.2).

Fig. 58.2 Causes of onycholysis. *Due to secondary colonization with Pseudomonas aeruginosa. SCC, squamous cell carcinoma; TFTs, thyroid function tests.

• Chronic exposure to water and irritants (e.g. soaps) is a common cause.

• Associated with psoriasis, onychomycosis, hyperthyroidism, and medications (Table 58.2).

Table 58.2

Drug-induced nail abnormalities.

Onychomadesis

• Proximal detachment of nail plate.

• When single digit, often due to trauma.

• Consider systemic cause (e.g. high fever, chemotherapy, post-erythroderma, post-viral) if multiple nails involved.

Pitting in Psoriasis

• Punctate depressions in the nail plate.

• Admixed with oil drop changes and other signs of nail psoriasis such as onycholysis, subungual debris (see Chapter 6).

Darier Disease

• Alternating longitudinal red and white streaks (i.e. erythronychia and leukonychia).

• Distal fissuring (notches).

Trachyonychia

• Rough, ‘sandpaper’ nails, often thin.

• Associated with alopecia areata or lichen planus >> psoriasis.

• May affect most or all nails, especially in children; often termed ‘20-nail dystrophy’.

Lichen Planus

• Nail thinning/atrophy, especially laterally.

• Sometimes dorsal pterygium (see below).

• See Chapter 9.

True Leukonychia

• White discoloration of nail.

• Punctate most common.

• Punctate > linear > diffuse.

• Linear bands may be transverse or longitudinal (see Darier disease).

• Punctate or transverse linear forms often due to trauma.

Apparent Leukonychia

• Nail plate appears white due to alterations in nail bed (e.g. edema).

• Secondary to drugs or systemic disease (e.g. hypoalbuminemia leads to Muehrcke’s lines).

• Terry’s nails: only distal several millimeters of nail plate unaffected; associated with liver disease.

• Lindsay’s nails: proximal half of nail is white and distal nail is red; associated with renal disease.

Koilonychia

• Spoon-shaped nails.

• Physiologic in children, associated with iron deficiency in adults.

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Apr 22, 2016 | Posted by admin in Dermatology | Comments Off

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