Article

Tumeurs et pseudotumeurs du canal anal et de l'anus

Acta Endoscopica (Impact Factor: 0.16). 06/2003; 33(3):357-365. DOI: 10.1007/BF03015749

ABSTRACT Les tumeurs malignes anales sont rares. Par contre, les lésions tumorales anales en relation avec lePapilloma Virus telles que le condylome acuminé (géant) sont des lésions nettement plus fréquentes. Pour comprendre les cancers qui surviennent
dans cette zone, il est nécessaire de connaître l'aspect histologique du canal anal et de l'anus.

En ce qui concerne les tumeurs malignes, une revue de notre série personnelle comme de la littérature montre clairement que
l'adénocarcinome du bas rectum, et non celui des glandes anales, est le carcinome le plus fréquent de cette région. Vient
ensuite mais son incidence augmente, le carcinome squameux du canal anal qui est parfois en relation avec l'HPV. Dans les
carcinomes squameux, il est recommandé de tenir compte des aspects de la différenciation basaloïde, kératinisante ou en microkystes
mucineux, ou de la notion de cancer intra-épithélial. Ces entités doivent être reconnues étant donné leurs pronostics biologiques
différents.

La tumeur de Buschke-Löwenstein, localement infiltrante ou condylome géant ou le carcinome verruqueux, peut être porteuse
d'HPV 6/11. Le carcinome basocellulaire peut se rencontrer dans la région anale; il doit être différencié du carcinome squameux:
son traitement étant purement local. La maladie de Paget primaire tend à récidiver fréquemment et à devenir invasive. Elle
devrait être différenciée de la forme de maladie de Paget associée à un carcinome colorectal synchrone (cytokératine 20 positive).
Les rares cas de mélanomes malins se développent le plus souvent chez des patients de race blanche et montrent des aspects
jonctionnels similaires au mélanome cutané. Chez les patients porteurs du SIDA, des lymphomes B à grandes cellules ont été
rapportés.

En ce qui concerne les néoplasies intra-épithéliales, la néoplasie intra-épithéliale anale de la zone squameuse ou de transition,
la dysplasie squameuse de la marge anale ou la maladie de Bowen ou encore les papuloses bowenoïdes sont reconnues.

Les lésions bénignes incluent des naevus naevocellulaires, des papillomes squameux, des hidradénomes papillaires des glandes
apocrines péri-anales, d'occasionnelles tumeurs mésenchymales ou nerveuses, l'hyperplasie fibro-épithéliale, les marisques
ou encore le polype cloaco-génique inflammatoire associés à un prolapsus muqueux ou des hémorroïdes.

Malignant anal tumours are rare but, in contrast, HumanPapilloma Virus (HPV)-related tumour-like conditions, including (giant) condyloma acuminatum, of the anus are more common diseases. To understand
the neoplasms that arise in this area it is necessary to be familiar with the histological features of the anal canal and
anus.

With regard to the malignant tumours, a review of our personal series as well as literature data indicate that adenocarcinoma
from the lower rectum, not from the anal glands, is the most common carcinoma in that region. It is not distinguishable from
the classical colorectal adenocarcinoma. Second in frequency but rising in incidence is the group of squamous cell carcinomas
(SCC) of the anal canal, which are often related with HPV infection. In the SCC it is advised to include statements on the
presence of basaloid features or mucinous microcysts, keratinisation and intraepithelial neoplasia. Entities that should be
recognized because of a different biological behaviour are SCC with mucinous microcysts and the small cell anaplastic (not
neuroendocrine) carcinoma. The locally invasive Buschke-Löwenstein tumour or giant (malignant) condyloma or verrucous carcinoma
may contain HPV 6/11. Basal cell carcinoma, the skin cancer, can be seen in the anal region and it should be distinguished
from SCC as it can be treated by local excision alone. Primary Paget's disease tends to recur frequently and to become invasive
and should be distinguished from Paget's disease associated with a synchronous or a metachronous colorectal carcinoma (cytokeratin
20 positive). The rare malignant melanoma occurs mainly in white patients and shows features like junctional activity similar
to these of cutaneous melanoma. In AIDS patients large B-cell malignant lymphomas can be seen.

Amongst the intraepithelial neoplasia, and intraepithelial neoplasia (AIN) in the transition and squamous zone, squamous dysplasia
at the anal margin or Bowen's disease and Bowenoid papulosis are recognised.

Benign lesions include naevocellular naevi, squamous cell papilloma, papillary hidradenoma of the perianal apocrine glands,
occasional reports of various mesenchymal or neurogenic tumours, the fibroepithelial hyperplasia or anal tag and the inflammatory
cloacogenic polyp associated with rectal mucosal prolapse and/or haemorrhoids.

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