What is Seborrheic Keratoses?

1 – Seborrheic keratoses
Seborrheic keratoses or seborrheic warts are common benign skin lesions, especially in the elderly. They belong to the category of benign epithelial tumors and those are the most common of them.
1.1 – DIAGNOSIS
Single or multiple, they save mucous membranes, palms and soles and are happy in the seborrheic areas of the face, neck or back. They appear most often around the age of 40 years but can occur in adolescence in men as in women.

There are different clinical forms of these lesions (see http://seborrheic-keratosis.com for pictures). They are usually pigmented, although limited, as placed on the skin as macule, papule or plaque with the stage of development, sometimes pedunculated, light brown in color (from yellow to dark brown). Their warty surface is progressively covered with a coating squamocolumnar keratotic fat. Lesion size varies from a few millimeters to several centimeters but rarely exceeds 1 cm.

When multiple, they can be distributed along skin folds, lines Blashko or Christmas tree.

Some lesions may be inflammatory due to the rupture of pseudocysts they contain or secondary to trauma or, more rarely due to infection.

The course is chronic and benign. These lesions are frequently asymptomatic but may become sensitive or itchy, erythematous or crusting, including the support of trauma.

Diagnostic tools: Histologically, they are composed of epidermal hyperplasia with strong predominance of basal cells. Hyperplasia is separated by invaginations of the stratum corneum forming cystic cavities or “horny pseudocysts” characteristics. Hyperpigmentation is common. There are different histological types of seborrheic keratosis: acantholytic, hyperkeratotic, reticulated or adenoid, irritated or clonal based on the preponderance of acanthosis, papillomatosis or of hyperkeratosis. The presence of atypical mitoses moderate or must discuss a local irritation or inflammation. In this case, there is often a dermal lymphocytic infiltrate, perivascular or diffuse lichenoid.

Most often, the diagnosis is easy and clinic.
Dermoscopy can be useful to confirm the clinical diagnosis. The analysis will identify dermatoscope it is not melanocytic lesion (without pigment network without globule, streak boss homogeneous and parallel). It shows the presence of pseudocysts horny as round structures of variable size, white or yellowish. Can also be observed pseudo-comedo, structures circumscribed, irregularly shaped, yellow-brown to brown-black, corresponding to keratin plugs within dilated follicular orifices.

Seborrheic keratoses and tumors: The seborrheic keratoses can coexist with other benign or malignant tumor (collision). The sign of Leser-Trelat is the sudden efflorescence of multiple pruritic seborrheic keratoses nature. This sign directs to the presence of a solid tumor, most commonly a gastric cancer or adenocarcinoma, rarely lymphoma or breast cancer or melanoma.

The etiology of these tumors is unknown. Sun exposure, the genetic predisposition have been implicated as possible contributing factors. There is often a family history identical, these lesions frequently appear in the photo-exposed areas. The role of viral infection with HPV has also been raised, particularly because of the clinical appearance of warts close. If the association of HPV with genital seborrheic keratoses has been shown in one study, it does not seem confirmed for seborrheic keratoses extragenital.

1.2 – DIFFERENTIAL DIAGNOSIS
Differential diagnoses to consider are: achrocordon, common warts, genital warts, the acrokeratosis verruciformis, tumors of the follicular infundibulum, the eccrine poromes, Bowen’s disease, squamous cell carcinoma, lentigo, nevus or melanoma.

The papular dermatosis stuccokératose and black variants are seborrheic keratoses in hyperkeratotic forms for the first and for the second acantholytic, demonstrated by the presence of somatic mutations (in these lesions) genes PIK3CA and FGFR3 like keratoses Seborrheic classics.
1.3 – TREATMENT
The treatment is most often dictated by aesthetic constraints. Symptomatic lesions can be treated by curettage or cryotherapy. Surgical treatment (resection) is recommended in cases of diagnostic uncertainty, especially with melanocytic tumor, where rapid growth or atypical features.
2 – REVERSE KERATOSIS FOLLICULAR
The inverted follicular keratosis or eccrine porome is a benign epithelial tumor, considered by some authors as a follicular tumor. This is the main differential diagnosis of seborrheic keratosis irritated.

This lesion is rarer than seborrheic keratosis, usually occurs in adults, middle age, after 60 years. Men are more frequently affected than women (2/1).

Clinically: This is a single lesion, firm, white or flesh-colored or pink, usually located on the face (cheeks, lips above). The size of the lesion is variable, often less than 1 cm in diameter but up to ten centimeters.

Histology: It is endophytic or exophytic lesions, often symmetrical and well circumscribed. The lesion consists of a proliferation of keratinocyte medium or large, distinct from each other with multiple elements dyskeratosis, hyperkeratosis topped ortho and para-keratosis. Basaloid cells can be observed in the periphery.

The discovery of inverted follicular keratoses can discuss Cowden syndrome because it is one of the minor criteria of this disease. The link between the follicular keratosis inverted the trichilemmome, seborrheic keratosis and verruca vulgaris is discussed.

The treatment is surgical.