HE x 50: Keratose, acanthose, et léger infiltrat chronique superficiel.

Low power, keratosis, acanthosis, and mild superficial chronic inflammatory infiltrate.

HE x 200: Présence de cellules à cytoplasme clair, irréguliérement réparties dans l'épiderme.

Medium power, presence of irregularly distributed cells in the épidermis, having a clear cytoplasm.

HE x 400: Ces cellules montrent peu d'anomalies nucléaires.

High power, the cells show little nuclear abnormalities.

PAS x 200: Le cytoplasme de ces cellules révèle une positivité vacuolaire.

PAS x 400: Vacuolar positivity is revealed in the cytoplasm of these cells.

Bleu Alcian x 400: Faible positivité des vacuoles.

Alcyan Blue x 400: Faint positivity of the vacuoles.

Diagnostic proposé:

Paget's disease is a malignant glandular tumor of the vulva that could be viewed either as a sweat gland carcinoma arising primarily from the intraepidermal portion of the glands (acrosyringium) or as a carcinoma of multipotential cells located along the epidermal basal layer that differentiate along glandular (sweat gland) lines.

Clinically, it presents as a crusting, elevated scaling erythematous rash in the labia majora, labia minora, and/or perineal skin. Microscopically, the epidermis contains large pale tumor cells that form solid nests, glandular spaces, or a continuous layer along the epidermal basement membrane and also in pilosebaceous structures and sweat ducts. A cleft often develops between the row of malignant cells and the overlying keratinocytes, resulting in a low-power appearance sometimes reminiscent of an acantholytic suprabasal bulla. Paget's disease can also be misinterpreted as malignant melanoma. It should be noted that the presence of melanin granules in some tumor cells does not rule out the diagnosis of Paget's disease. Histochemically, some or all of the tumor cells contain acidic mucus, as evidenced by their positivity for Mayer's mucicarmine and aldehyde fuchsin stains. Immunohistochemically, they are reactive for low-molecular-weight keratin, EMA, CEA, and B72.3125,126,130,131. In the majority of the cases, they also stain for GCDFP-15, a marker of apocrine differentiation. S-100 protein stain is positive in about one third of the cases, but HMB-45 is negative. The ultrastructural features are indicative of glandular rather than keratinocytic or melanocytic differentiation. Overexpression of c-erbB-2 oncoprotein and of the ras oncogene product p21 has been found in about half the cases.

Paget's disease of the vulva differs in several respects from Paget's disease of the breast. The latter is nearly always associated with an underlying carcinoma that may be intraductal or invasive, and the intraepidermal malignant cells are more often than not mucin-negative. In contrast, the majority of the cases of vulvar Paget's disease are not associated with an invasive underlying carcinoma and are usually (although not always) positive for mucin stains, as previously indicated. The incidence of underlying invasive carcinoma in vulvar Paget's disease ranges from zero to 30% depending on the series. Occasionally, Paget's disease is seen in association with VIN, in keeping with its presumed origin from multipotential epidermal basal cells.

If no invasive component is found in the resected specimen, the prognosis is good. Metastases do not occur under these circumstances, although local recurrence may supervene, sometimes in the form of invasive carcinoma. Therefore excision should include a margin of normal skin and the subcutaneous tissue to incorporate all sweat glands. Unfortunately, the microscopic extent of the disease is often greater than that suspected from clinical examination, and this should be taken into account at the time of surgery. Frozen sections are useful to determine the status of the margins. The disease may also recur in the vulvar split-thickness skin graft.