KERATOSE ACTINIQUE HYPERTROPHIQUE DGNRE.
Limites de rsection saines
(Diagnostic diffrenciel : Kerato-acanthome, l'volution
n'est pas en faveur)
Actinic keratosis (Ackerman's Surgical Pathology)
In that portion of the epidermis exposed to sunlight,
chiefly that of the near ultraviolet spectrum, a sequence of atrophic,
dysplastic, and eventually hyperplastic changes known as actinic or solar
keratosis may develop. The term "senile" keratosis often used as a synonym
is inappropriate. An increased incidence of these changes has been found
in renal transplant recipients, particularly in the lip region.
Histologically, actinic keratoses involve the interfollicular
epidermis, sparing the follicular apparatus and the intraepidermal portion
of the sweat duct. The stratum corneum is replaced by a parakeratotic
scale. Excessive production and accumulation of this scale lead to the
formation of cutaneous horns The granular layer is generally absent
except at and about the follicular orifices. The malphigian layer shows
disorderly maturation as well as individually dysplastic and dyskeratotic
cells. On occasion, suprabasal acantholysis produces vesicles reminiscent
of those seen in pemphigus vulgaris. Foci of basal cell proliferation
resembling basal cell carcinoma may occur. Not infrequently, the basal
melanocytes participate in the proliferation and atypia, resulting in
a combination of actinic keratosis and actinic melanosis. Such cases appear
clinically as heavily pigmented lesions.The papillary dermis is often
chronically inflamed, and basophilic degenerative changes are prominent
in the collagen. In florid forms of actinic keratosis, the atypical epithelial
proliferation produces irregularly elongated acanthotic ridges, and this
process extends down the external root sheaths of the hair follicles.
In such cases, the differential diagnosis with superficially invasive
squamous carcinoma inevitably arises.
Accumulation of p53 protein, presumably as a result of mutation, has been
found in almost three fourths of
actinic keratosis lesions and found to correlate with the degree of atypia.
Actinic keratoses may be treated by a variety of methods freezing, superficial
curettage, application of
antineoplastic chemotherapeutic agents, and surgical excision.Excision
is, in fact, unnecessarily radical
therapy except for the more florid and infiltrative types and those not
responding to topical 5-fluorouracil.
For more go to
(Ref. Pathology of the skin, PH McKee, 3rd Ed. Elsevier-Mosby)