Page 46 - The Netter Collection of Medical Illustrations - Integumentary System_ Volume 4 ( PDFDrive )

Plate 2-19 Integumentary System

LICHENOID KERATOSIS

Lichenoid keratoses are common benign skin growths
also known as lichen planus–like keratoses. These are
most often solitary, benign skin tumors and may be
found anywhere on human skin. They are more
common during adulthood. The keratosis may be mis-
diagnosed as a non-melanoma skin cancer, most com- Lichenoid
monly a superficial basal cell carcinoma. keratosis
Clinical Findings: Lichenoid keratoses are most fre-
quently found on the upper trunk and upper extremi-
ties. The incidence is equal in males and females, and
there is no race predilection. They are rare in child-
hood. They typically manifest as pruritic, red to slightly
purple patches and thin plaques. Occasionally, a patient
notices that the area arises in a preexisting seborrheic
keratosis or solar lentigo. Most lichenoid keratoses are
1 cm or smaller in their largest diameter. Most patients
present to their physician with a chief complaint of
tenderness, itching, or bleeding secondary to scratching
or rubbing of the lesion. The lesions may have a strik-
ing resemblance to the rash of lichen planus; the dif-
ferentiating factor is that a lichenoid keratosis is solitary,
whereas lichen planus includes a multitude of similar
skin lesions. These skin growths have no malignant
potential. It can be difficult to differentiate lichenoid
keratoses from inflamed seborrheic keratoses, basal cell
carcinomas, actinic keratoses, or squamous cell carcino-
mas. Therefore, a biopsy of the lesion is prudent to
discern a pathological diagnosis.
There are a few unusual clinical variants, including Lichenoid keratosis. A solitary growth in
an atrophic form and a bullous type of lichenoid kera- Lichen planus. Widespread pruritic purpilsh comparison to the widespread nature of
tosis. The differential diagnosis of these two variants papules and plaques, some with Wickham striae. lichen planus. Histology can be identical.
includes conditions such as lichen sclerosis for the
former and autoimmune blistering diseases for the
latter. The dermatoscope has become an indispensable
tool and can be helpful in diagnosing lichenoid kerato-
sis. Lichenoid keratoses have been shown to have a
localized or diffuse granular-type pattern under derma-
toscopic viewing. This finding should help differentiate
these tumors from melanocytic tumors.
Histology: On histological examination, a lichenoid
keratosis has a symmetric, well-circumscribed area of
intense lichenoid inflammation along the basement
membrane region. There is disruption of the basilar
keratinocytes. This leads to the appearance of a number
of necrotic keratinocytes, also called Civatte bodies.
Civatte bodies are seen in almost all cases of lichenoid
keratosis and also in lichen planus. There is pronounced
sawtooth hypergranulosis and pronounced acanthosis.
There is no atypia of the involved keratinocytes, thus
ruling out an inflamed actinic keratosis. The underlying
inflammatory infiltrate is made up almost entirely of A lichenoid lymphocytic infiltrate is seen along the dermal-epidemal junction. Disruption of the dermal-
lymphocytes. However, it is not uncommon to find a epidermal junction is prominent. Necrotic keratinocytes are seen in the epidermis.
rare eosinophil or plasma cell anywhere throughout
the infiltrate. The pathological differential diagnosis
includes lichen planus. The clinical history is very
important: Whereas a lichenoid keratosis is a solitary
lesion, the same findings in a biopsy specimen taken keratosis. The specific precipitating factor may be entire lesion was not removed with the biopsy speci-
from a widespread rash of purple, flat-topped papules trauma. Chronic rubbing has been implicated in induc- men, no treatment is necessary. Use of a topical cor-
would be more consistent with the diagnosis of lichen ing lichenoid keratoses from lentigines. The role of ticosteroid cream or ointment twice daily for 1 to
planus. This example illustrates the importance of human papillomavirus (HPV) in causing lichenoid 2 weeks after healing of the biopsy site is likely to lead
including the clinical history on a pathology report. keratoses has been studied, but no firm conclusions to complete resolution of the lichenoid keratosis. Other
Pathogenesis: The exact etiology of a lichenoid kera- have been made. treatment options include light cryotherapy or a light
tosis is unknown. It is believed to be caused by an Treatment: Most biopsies of a lichenoid keratosis curettage after anesthesia. Benign lichenoid keratoses
inflammatory response to a lentigo or a thin seborrheic result in complete resolution of the lesion. Even if the rarely if ever recur.

32 THE NETTER COLLECTION OF MEDICAL ILLUSTRATIONS