Page 214 - The Netter Collection of Medical Illustrations - Integumentary System_ Volume 4 ( PDFDrive )

Plate 7-3 Integumentary System

COMMON FINGERNAIL DISORDERS

Mees’ lines. Mees’ lines
COMMON NAIL DISORDERS on fingernails and hyper-
pigmentation of the soles
are characteristic
Nail disorders are frequently encountered in the clini- of arsenic poisoning.
cal setting. They can occur secondary to an underlying
systemic disorder or as a primary disease of the nail Acute paronychia.
unit. The nail unit consists of the nail matrix, bed, and Tender red nail fold,
plate and the proximal and lateral nail folds. Disorders commonly caused
of the nail plate and nail bed can manifest in a variety by Staphylococcus
of ways. Systemic disease can manifest through changes aureus
in the nail unit. Beau’s lines and Mees’ lines of the nail
are two nail findings seen in systemic disease. Beau’s
lines are caused by a nonspecific halting of the nail Branching hyphae indicative
matrix growth pattern, and Mees’ lines are specific for of a dermatophyte infection
heavy metal toxicity. Dilation of the capillaries of the
proximal nail fold or cuticular erythema can be a sign
of connective tissue disease. The complete skin exami-
nation should also include an examination of the nails,
because they offer insight into the patient’s health.
One of the most serious nail unit disorders is mela-
noma of the nail matrix. Melanoma may manifest as a
linear, pigmented band along the length of the nail. As
time progresses, the proximal nail fold and hyponych-
ium may also become pigmented and involved with
melanoma. The finding of pigment on the proximal nail
fold has been termed Hutchinson’s sign. This sign is not
seen in subungual hematomas. All new pigmented nail
streaks should be evaluated and a biopsy considered.
The biopsy requires nail plate removal and retraction
of the proximal nail fold. The biopsy of a pigmented
nail streak is performed within the nail matrix. Biopsies
of the nail matrix may lead to a thinner nail or to
chronic nail dystrophy due to disruption of the matrix.
Subungual melanoma tends to be diagnosed late,
because these tumors are easily overlooked or passed Onychomycosis of the fingernails. A KOH preparation
off as a subungual hematoma. It is critically important is done by scraping the crumbling nail plate
to differentiate the two. and examining it under the microscope. Psoriatic arthritis with nail
Subungual hematomas are frequently encountered. involvement. Sausage-shaped
Most are caused by direct trauma to the nail plate and digits, psoriatic skin plaques
nail bed, which causes bleeding between the plate and and nail changes
bed. Acute hematomas can be very painful. Most acute
subungual hematomas are on the fingers and are caused
by a crush injury or by a direct blow to the nail plate. Nail pits
As the blood accumulates under the nail plate, the pres-
sure created can cause excruciating pain. This can be
easily treated by nail trephination. A small-gauge hole Transverse ridges
is bored into the overlying nail plate with a hot, thin
metal object or small drill. Once the nail plate has been
punctured, the blood that has accumulated under the
nail freely flows out of the newly formed channel, and Onycholysis
near-immediate pain relief is achieved. Most traumatic
injuries to the nail unit do not cause these very painful Subungal hematoma from trauma
hematomas but rather cause small amounts of blood to Psoriatic nail changes
accumulate under the nail plate. Pain is absent or
minimal. Most people remember some trauma to the
nail, but others do not. This form of subungual hema-
toma can involve small portions of the nail or the entire
nail. There is often a blue, purple, and red discoloration exists, a nail biopsy should be considered. The nail plate Onychocryptosis (ingrown nail) is almost universally
of the underlying nail. Occasionally, the nail plate has is removed, and a subungual hematoma is easily distin- seen in the great toenail. It is caused by burrowing of
a black appearance and is easily confused with subun- guished from a tumor. Most subungual hematomas the lateral portion of the nail plate into the lateral nail
gual melanoma. The history can be misleading in these slowly grow outward toward the distal free edge of the fold. As the nail punctures the lateral nail fold, it sets
cases, because many patients with and without mela- nail. As the nail grows, its most proximal portion off an inflammatory reaction that causes edema, redness,
noma remember some form of trauma to the nail that appears normal. The entire subungual hematoma even- pain, and occasionally purulent drainage. Secondary
might lead the clinician to pass the lesion off as a sub- tually grows out and is shed or clipped off once it passes infection is common. Ambulation may become difficult
ungual hematoma. If any doubt about the diagnosis the hyponychium. because the pain forces the patient to avoid pressure.

200 THE NETTER COLLECTION OF MEDICAL ILLUSTRATIONS