Prsentation Clinique

H 65 ans, lsion kratosique de la main droite datant de plusieurs mois.    

Pathologie:

Le faible agrandissement objective une lsion limites d'allure arciforme, avec hyperkratose, forme de traves anastomotiques de cellules pidermodes, avec un bec latral, un infiltrat inflammatoire et une lastose du derme adjacent. Les traves prsentent une anisonuclose, et une dyscaryose modres.

Une infiltration du derme est observe ( HE x 200,  HE x 400), ainsi que des figures de mitoses, parfois atypiques (PAS).

Diagnostic Propos:

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

Actinic keratosis

(Ref. Pathology of the skin, PH McKee, 3rd Ed. Elsevier-Mosby)