Punch biopsies are not effective in differentially diagnosing for EMPD and as a result, excisional biopsies of the affected area are taken [XX]. A positive test result for EMPD shows increased numbers of large polygonal cells with a pale bluish cytoplasm, large nucleus and nucleolus, infiltrating the epidermal layer. These neoplastic cells can be found singly scattered or can appear in groups called nests.Paget cells contain mucin and cytokeratins which can be used in the diagnosis of EMPD [8] MUC5A2 is found in EMPD of the vulvar and male genitalia regions whereas MUC2 is expressed in perianal EMPD. Loss of MUC5A2 can indicate an invasive spread. Immunohistochemistry (IHC) can be used to determine whether EMPD is either primary or secondary. Primary EMPD tests positive for CK7 but negative for CK20, whereas secondary is positive for both. Lack of positivity for hormone receptors and HER2 protein is overexpressed meaning that the cells are dividing rapidly and can be indicate an aggressive and more recurrent disease. Classification
Primary EMPD is of cutaneous origins and is found within the epidermis or the underlying apocrine glands. Although it is limited to the epithelium, it has potential to spread and progress into an invasive tumour, metastasising to the local lymph nodes and distant organs. This form of EMPD is not associated with an adenocarcinoma.The secondary form results due to an underlying adenocarcinoma spreading to the epidermis.
Similar to the primary form, if secondary EMPD invades the dermis, the neoplastic cells can metastasise to the lymph nodes and in some cases, the dermis.According to the Wilkinson and Brown subclassification system, there are three subtypes for each classification. Treatment
Many chemotherapy treatments have been used, however the results are not desirable as prognosis remains to be poor. Surgery remains to be the preferred treatment of choice. Wide local excision with a 3 cm margin and intra-operative frozen sections are suggested, due to high risk of local extension despite normal appearing tissue. In cases where Paget cells have invaded the dermis and metastasized, complete removal is often unsuccessful. Recurrence is a common result. Lymphadenoectomy is often performed for infiltrative cases. In lieu of surgery, radiotherapy is also an option and is especially preferred for elderly patients or for inoperable cases where the tumour size is too large. This form of treatment is also considered as possible adjuvant therapy following excision to combat the high recurrence rate. However, there are side effects of radiotherapy, including but not limited to: vulvitis, post-radiation atrophy of mucus membranes, vaginal stenosis and sexual dysfunction.Laser therapy and photodynamic therapies were also used in the past, but it was discovered the carbon dioxide laser did not penetrate deep enough and both treatment modalities resulted in high recurrence rates.Topical chemotherapy treatments are effective, with imiquimod showing promising results. However, overall survival begins to decline 10 months following treatment with chemotherapy.