Page 128 - The Netter Collection of Medical Illustrations - Integumentary System_ Volume 4 ( PDFDrive )

Plate 4-43 Integumentary System

Generalized lichen planus
LICHEN PLANUS Classic lichen
planus. Purple,
polygonal, flat-
Lichen planus is a common inflammatory skin disease. topped, pruritic
It is unique in that it can affect the skin, the mucous papules
membranes, the nails, and the epithelium of the hair
follicles. Lichen planus most commonly affects the skin,
but the other areas can be involved either solely or in
conjunction with one another. Lichen planus that
involves the skin has a tendency to spontaneously remit
within 1 to 2 years after onset, whereas the oral version
is almost always chronic in nature.
Clinical Findings: Lichen planus can affect people at
any age, but it is much more common in adulthood. It
has no gender or racial predilection. The rash classically
has been described as flat-topped, polygonal, pruritic,
purple papules. Frequently, a whitish, lacy scale,
referred to as Wickham’s striae, overlies the papules.
Lichen planus is unusual in that the pruritus causes the
patient to rub the area, rather than scratch. Lichen
planus exhibits the Koebner phenomenon, and often
areas of linear arrangement are seen secondary to
trauma or rubbing. This is helpful when clinically
examining a patient, because scratch marks and excoria-
tions are rarely seen, whereas lichenification from
repeated rubbing of the lesions is frequently seen. The
rash has a tendency to be more prominent on flexural
surfaces, especially of the wrists. The glans penis is
another distinctive location in which lichen planus
commonly occurs.
Many clinical variations of lichen planus have been
described. An afflicted individual may have more than
one morphology. Hypertrophic lichen planus has the
appearance of thickened, scaly plaques with a rough or
verrucal surface. There may be areas on the periphery
that appear more classic in nature. This variant can be
difficult to diagnosis clinically, and often a biopsy is
required. It also can be difficult to treat effectively, and
it runs a chronic course. Rarely, hypertrophic lichen
planus has been reported to transform into malignant
squamous cell carcinoma. Bullous lichen planus is an
extremely uncommon variant that usually occurs on the
lower extremities. The vesicle or bulla typically forms
within the center of the lichen planus lesion.
Lichen planopilaris is the term given to describe lichen
planus affecting the terminal hair follicles. This is most
common on the scalp and leads to a scarring alopecia.
The typical findings are small, erythematous patches
surrounding each hair follicle. As the disease progresses,
loss of hair follicles is observed, signifying that scarring
is taking place. The central crown is the area most often
affected. It is uncommon for the entire scalp to be Oral lichen planus Wickham’s striae. White Histology of lichen planus.
affected. Once scarring has occurred, the hair loss is reticulated patches on the Lichenoid lymphocytic
permanent. Lichen planopilaris runs a chronic waxing buccal mucosa infiltrate with “saw-toothing”
and waning clinical course. of the rete ridges, decreased
Lichen planus may affect the mucous membranes of granular cell layer, and a
the oral cavity, the genital region, and the conjunctiva. Max Joseph space at the
These areas appear as glistening patches with lacy, dermal-epidermal junction.
white reticulations on the surface. Mucous membrane
lichen planus has a higher tendency to ulcerate than the
cutaneous form does. There have been reports of
malignant transformation to squamous cell carcinoma.
For this reason, long-term follow-up is required. findings. The exact pathomechanism has yet to be of eosinophils should lead one to consider the diagnosis
Lichen planus may also affect the nail matrix and nail described. of a lichen planus–like drug eruption or lichenoid
bed, leading to dystrophy and nail abnormalities. The Histology: The lesions show characteristic findings contact dermatitis.
most frequently seen nail abnormality is longitudinal that include a dense lichenoid lymphocytic infiltrate Treatment: Isolated lesions can be treated with
ridging, but the most characteristic nail finding is pte- along the dermal-epidermal border. Necrotic keratino- topical corticosteroids. Up to two thirds of skin lesions
rygium formation. cytes are frequently encountered within the hyperplas- resolve spontaneously. Patients with widespread disease
Pathogenesis: Lichen planus appears to be mediated tic epidermis and have been named Civatte bodies. present a therapeutic challenge. Ultraviolet photother-
by an abnormal T-cell immune response. The T cells Hypergranulosis is a prominent feature as is the “saw- apy, oral corticosteroids, and oral retinoids such as
act locally on the keratinocytes to induce the clinical tooth” pattern of epidermal hyperplasia. The presence acitretin and isotretinoin have been used.

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