Extramammary Paget disease

Extramammary Paget disease is an uncommon cancer characterised by a chronic eczema-like rash of the skin around the anogenital regions of males and females. Under the microscope extramammary Paget disease looks very similar to the more common type of mammary Pagets disease that occurs on the breast. Extramammary Paget disease most commonly occurs in the vulva of women aged between 50-60 years.

Extramammary Paget disease has been classified into several subtypes.

• Type 1a primary cutaneous extramammary Paget disease arises from apocrine glands within the epidermis (in situ) or underlying skin appendages
• Type 1b primary cutaneous extramammary Paget disease (15-25%) is associated with invasive Paget disease or adenocarcinoma in situ.
• Type 2 extramammary Paget disease originates from underlying anal or rectal adenocarcinoma
• Type 3 extramammary Paget disease originates from bladder adenocarcinoma

Sometimes the extramammary Paget disease has been present for 10-15 years before evidence of cancer or metastases appear.

What are the signs and symptoms?

The most common symptom is a mild to intense itching of a lesion found around the groin, genitalia, perineum or perianal area. Pain and bleeding may occur from scratching lesions that have been around for a long time. Thickened plaques may form that can become red, scaly and crusty. Although they may appear similar to eczema, they fail to clear up with topical steroid creams.

Extramammary Paget disease

Vulvar Paget disease

Axillary Paget disease

Ï Vulvar Paget disease

What sites are affected

In women the most common area involved is the vulva. First symptoms are usually itching and burning of of one or more persistent plaques. These may spread to the labia, mons pubis, vagina and thighs. Perianal lesions may extend up into the anal canal.

The location of extramammary Paget disease is useful in predicting the risk of associated cancer. For example, 25-35% of extramammary Paget disease arising near the anus is associated with an underlying colorectal cancer.

Diagnosis of extramammary Paget disease

Skin biopsy of the lesion is performed to get an accurate diagnosis of extramammary Paget disease as there are several other genital skin diseases that may appear similar. Under microscopy, the presence of Paget cells along with other histological findings confirms diagnosis. Special stains may be necessary to distinguish Paget disease from early melanoma (melanoma in situ).

Further tests may include:

• Evaluation of lymph nodes by ultrasound scan or fine needle aspirate
• Search for other malignancies including PAP smear (cervical smear), pelvic imaging to look for underlying cancer, colonoscopy, mammography.

What is the treatment of extramammary Paget disease?

Wide local excision, vulvectomy, or if available, margin-controlled surgical excision (Mohs micrographic surgery) is the standard treatment for extramammary Paget disease . Paraffin sections are preferred over frozen sections. The margin is sometimes difficult to define particularly when lesions are spread sporadically throughout the anogenital region. Reconstruction may require skin grafting or flap repair.

Recurrence is common (30-50%), so patients should be re-examined every 3 months after surgery for the next 2 years, after which annual follow-ups are recommended. Recurrence generally leads to further surgery.

Non-surgical treatments for recurrent disease may include:

• Radiotherapy
• Laser ablation
• Photodynamic therapy
• 5-fluorouracil cream
• Imiquimod cream

Paget disease has a low mortality.