Kératoacanthome de la marge anale

Calcified Keratoacanthoma with Tumoral Calcinosis in a 10-year-old Boy: A mere Co-incidence?

Keratoacanthoma (KA) is a rapidly evolving benign cutaneous tumor, occurring in elderly individuals with a tendency towards spontaneous regression and histopathologic similarity to squamous cell carcinoma. Tumoral calcinosis is an uncommon condition, associated with the deposition of painless calcific masses. The occurrence of these two conditions in the same patient is a rarity itself, whereas deposition of calcium within the KA lesion in our 13-year-old patient makes it even more intriguing. Such an association has been seldom reported in the literature, and this prompted the current report.

Keratoacanthoma: hyperplasia, benign neoplasm, or a type of squamous cell carcinoma?

Keratoacanthomas are common self limited squamous proliferations. They have been considered a benign neoplasm with involution and complete resolution within few months. Although considered the prototypical example of cutaneous pseudomalignancy, some believe that these tumors are squamous cell carcinomas and through the years there have been sporadic reports of "metastasizing keratoacanthomas". The question has been raised as to whether keratoacanthoma is an unreliable histological diagnosis or these tumors have a latent, albeit rare, malignant potential. To date, just a handful of "metastasizing keratoacanthomas" have been reported. Since a benign lesion is incapable of metastasis, some other explanation must be considered; the most likely one being a misdiagnosis. While it is clear that in some cases, the histological and cytological features of squamous cell carcinoma and keratoacanthoma are difficult to distinguish by current techniques, these occasional limitations in diagnosis do not make keratoacanthomas a carcinoma. We believe the evidence supports that keratoacanthomas are benign squamous proliferations. The diagnosis can be made with confidence in appropriate biopsies and using well established clinicopathological criteria.

[Anal and anal margin tumors]

Tumors of the anal canal and anal margin are rare. They may raise specific problems for the pathologist. Benign tumors mainly consist of condylomas, cloacogenic polyps and fibro-epithelial polyps. Cancers are infrequent and consisted of well-differentiated squamous cell carcinoma, or poorly differentiated basaloid squamous cell carcinoma. The other malignant tumors are very rare.