Extramammary Paget Disease 

Updated: Jul 21, 2021
Author: Richard Harold "Hal" Flowers, IV, MD; Chief Editor: Dirk M Elston, MD 

Overview

Background

Extramammary Paget disease (EMPD) is morphologically and histologically identical to mammary Paget disease (PD) of the nipple, the primary difference being the anatomic location. EMPD most commonly targets the vulva in women and the perianal region in men, but it can affect other apocrine-rich cutaneous sites as well. EMPD may arise as a primary intraepithelial adenocarcinoma (primary EMPD), or it may develop as an extension of an underlying visceral malignancy or adnexal adenocarcinoma (secondary EMPD). EMPD is not a common disorder, but it must be considered in the differential diagnosis of patients with chronic genital or perianal dermatitis.

PD of the nipple was first described by Sir James Paget in 1874. EMPD was first recognized and reported as a distinct clinical entity by Radcliffe Crocker in 1889, who described a patient with erythematous patches on his penis and scrotum.

Please see the following for more information on these associated conditions:

  • Paget Disease

  • Mammary Paget Disease

  • Rehabilitation for Paget Disease

Pathophysiology and Etiology

The precise pathogenesis of extramammary Paget disease (EMPD) is unclear. EMPD may be primary or secondary in its etiology. Primary EMPD is thought to arise as a primary intraepithelial adenocarcinoma in most cases, while secondary EMPD represents extension of an underlying adnexal adenocarcinoma or visceral malignancy. The majority of cases of EMPD are primary.

In both forms of EMPD, the epidermis becomes infiltrated with neoplastic cells showing glandular differentiation. Tumor cells may originate from apocrine gland ducts or from keratinocytic stem cells. The proliferative neoplastic cells are Paget cells, which have abundant pale cytoplasm and large pleomorphic nuclei. The cells may be arranged singly or in small groups in early lesions, and usually spread into the contiguous epithelium of eccrine ducts and hair follicles. While the greatest concentration of tumor cells is in the lower part of the epidermis, the entire thickness of the epidermis may also be involved. Rarely, Paget cells may invade the dermis.[1]

The cause of primary EMPD is unknown, but is thought to arise as a primary intraepidermal neoplasm from the apocrine gland ducts or pluripotent keratinocyte stem cells. Toker cells have also been suggested as potential precursors. Toker cells are epithelial clear cells found in the areolar and nipple areas of the breast, vulvar region, and in other areas of the skin bearing apocrine glands.[2] The cells are thought to be a constant feature of the interface between the epidermis and the epithelium in these areas.[3] It has more recently been suggested that Toker cells may be benign precursors of Paget cells.[4, 5]

A minority of EMPD cases (range, 7-40%; but most often reported as 25%) are secondary to an underlying internal malignancy, with epidermal invasion of malignant adenocarcinoma cells.[3, 6] Urothelial and anorectal carcinomas are the most common underlying visceral malignancies.[1] The anatomic location of EMPD plays a role in predicting the risk of underlying carcinoma. For instance, genital disease is associated with carcinoma in about 4-7% of patients.[7] Perianal disease is associated with underlying colorectal carcinoma in 25-35% of cases.[7] The anatomic location of EMPD also may be indicative of the specific type of underlying malignancy. For example, EMPD found in the penoscrotal region is more likely to be associated with an underlying genitourinary malignancy, while perianal EMPD may be indicative of urogenital or gastrointestinal malignancy.[7]

Rare cases of EMPD associated with tumors arising in distant organs without direct epithelial connection to the affected epidermis have been reported. Roy et al reported EMPD in a retrorectal dermoid cyst.[8] No clear evidence supports a causal link between these distant tumors and cutaneous EMPD.

Epidemiology

Extramammary Paget disease (EMPD) is a relatively rare condition; there are only several hundred cases in the world literature. It most commonly appears in individuals aged 50-80 years, with a peak incidence at age 65 years. Women are overall more commonly affected by EMPD than men. The female-to-male ratio was 4.5:1 in one series of 55 patients and 3:1 in another series of 197 patients.[7] Of note, a nearly 1:1 male-to-female ratio of EMPD has been reported in Asian patients, although the reason for this has not yet been elucidated.[9, 10] EMPD is more frequently seen in Whites and is rarely seen in the Black population.[11] Familial occurrence has been reported in a few rare cases.[12, 13, 14] No genes have currently been implicated.

Prognosis

The prognosis for extramammary Paget disease (EMPD) is generally favorable, but it depends on early diagnosis with definitive surgical treatment. The course of EMPD may extend over a period of 10-15 years without evidence of cancer or metastases.[15] In a minority of patients, tumor cells infiltrate the dermis, adnexa, or lymph nodes. Both mortality and morbidity are increased in these patients because of the extensive surgical treatment or chemotherapy required.

Full recovery is possible in patients with purely epidermal disease and negative margins after micrographic surgery. However, the recurrence rate of EMPD is 30% even with margin control. Prognosis is also dependent on whether the EMPD is primary or secondary to an underlying malignancy. One study analyzing 196 reported cases of EMPD showed a mortality of 18% for patients without associated carcinoma and 46% for those with underlying carcinoma over the studied 20-year period. These mortalities were due to either metastatic EMPD or a metastatic associated internal malignancy.[7]

Perianal disease, dermal invasion, and two or more lymph node metastases are poor prognostic indicators. Other characteristics associated with worse survival include increased serum carcinoembryonic antigen (CEA) levels, tumor thickness over 4 mm, distant metastasis, and the presence of nodules in the primary lesion. Some patients develop recurrences more than 15 years after initial treatment, making long-term clinical follow-up ideal.[1]

 

Presentation

History

The possibility of extramammary Paget disease (EMPD) should be carefully considered in any patient with chronic dermatitis of the groin, vulva, or perianal area that is recalcitrant to treatment. Patients with EMPD usually present with nonresolving eczematous lesions in the groin, genitalia, perineum, or perianal area.[16] The most common symptom of EMPD is intense pruritus; most patients have only pruritus in the affected area and no other symptoms. Pain and bleeding may occur in longer-standing lesions. Burning, tenderness, and edema may also be experienced over the area of involvement.

Physical Examination

At clinical examination, extramammary Paget disease (EMPD) may appear as chronic intertrigo, eczematous dermatitis, or presumed tinea cruris. Lesions can be nonspecific, making diagnosis challenging. EMPD usually has been present for several years before biopsy is performed to confirm the diagnosis, with a reported median delay of 2 years before proper diagnosis.[1] The genitalia, perineum, axillae, and external auditory canal are rich in apocrine glands; therefore, these are the usual sites of EMPD involvement, which is often multifocal. In males, the penoscrotal and perianal areas are most frequently involved, as is the vulva in women.[1] Rarely, it may occur in the buttock, knee, glans penis, thigh, abdomen, umbilicus, lower anterior chest, and scalp.[17] See the image below.

Classic appearance of extramammary Paget disease ( Classic appearance of extramammary Paget disease (EMPD). Courtesy of Kenneth E Greer, MD.

Early skin changes may be subtle and vary according to location. Initially, only slight erythema, crusting, and increased maceration may be noted. Pruritus commonly leads to prominent excoriations and lichenification. Scattered areas of erosion and white scale can result in a characteristic "strawberries and cream" appearance (see the image below).[1] Lesional progression leads to a unilateral sharply marginated plaque with distinct erythema. Hypopigmentation or hyperpigmentation occurs, and small pale islands are often observed over the lesion.

Classic "strawberries and cream" appearance of ext Classic "strawberries and cream" appearance of extramammary Paget disease (EMPD). Courtesy of Kenneth E Greer, MD.

Hard nodules and regional lymph node enlargement may develop in cases with an underlying carcinoma. "Underpants-pattern erythema" is described in cases of genital EMPD as a result of metastases to the lymphatic system. This pattern starts in the groin and spreads peripherally to areas typically covered by the underwear. This portends a grim prognosis owing to the possibility of rapidly fatal distant metastases.[1]

 

DDx

Diagnostic Considerations

Differential diagnosis includes squamous cell carcinoma, condyloma acuminata, hidradenitis suppurativa, and lichen sclerosis. Other considerations are listed below.

Differential Diagnoses

 

Workup

Approach Considerations

The diagnosis of extramammary Paget disease (EMPD) requires a high degree of clinical suspicion, especially in patients presenting with persistent eczematous lesions failing a 6-week trial of topical therapies. Skin biopsy with pathologic correlation is the basis of diagnosis.[18]  A detailed review of systems and physical examination should be performed in all patients following a diagnosis of EMPD. The examination should include the following:

  • Palpation of all lymph nodes
  • Rectal examination
  • Sigmoidoscopy
  • Cystoscopy

Additionally, women require pelvic examination with a Papanicolaou test, breast examination, and colposcopy.

Imaging Studies

Imaging studies in extramammary Paget disease (EMPD) should be directed by the anatomic location of the involved skin and the sex of the patient. Imaging studies should be used to augment physical and endoscopic examination in assessing possible undetected internal malignancy.[7]

Positron-emission tomography (PET) may be helpful in assessing regional lymph nodes and locating distant disease, especially in patients with dermal invasion noted on initial skin biopsy specimens.[19]

Skin Biopsy and Histologic Findings

Because extramammary Paget disease (EMPD) extends beyond the visibly involved margins, obviously involved skin should be examined by using transverse frozen sections or serial vertical sections. A skin biopsy specimen should be obtained for initial diagnosis. Repeat biopsies are warranted to evaluate possible EMPD in patients in whom ongoing therapy is ineffective.

On histologic examination of EMPD, the epidermis is diffusely infiltrated with large vacuolated cells that have a bluish cytoplasm called Paget cells (see the images below). There are two types of Paget cells: classic type (type A) and signet-ring type (type B). The classic type is characterized by vesicular nuclei with prominent nucleoli and abundant pale cytoplasm, while the signet-ring type is characterized by an eccentrically displaced nucleus with large cytoplasmic mucin droplets.[20, 21] These distinctive cells are found in the lower epidermis and may proliferate to the rete ridges and adnexa. The epidermis shows varying degrees of acanthosis, hyperkeratosis, and parakeratosis. With histochemical analysis, Paget cells are stained with sialomucin by using periodic acid–Schiff (PAS) stain followed by diastase digestion.

Classic histology of extramammary Paget disease (E Classic histology of extramammary Paget disease (EMPD). Clusters of large cells with pale, vacuolated cytoplasm scattered throughout the epidermis.
High power image of extramammary Paget disease (EM High power image of extramammary Paget disease (EMPD). Clusters of large cells with pale, vacuolated cytoplasm scattered throughout the epidermis.

It is important to keep in mind the differential diagnosis of tumors with an epidermotropic growth pattern and the importance of immunohistochemical staining in the histologic workup of such tumors. The following should all be considered[22] :

  • Squamous cell carcinoma in situ
  • Melanoma
  • Mycosis fungoides
  • Eccrine porocarcinoma
  • Sebaceous carcinoma of the eyelid
  • Mammary Paget disease (PD) and EMPD
  • Merkel cell carcinoma
  • Epidermotropic metastases

Immunohistochemical staining can be used to identify Paget cells, differentiate primary from secondary EMPD, and distinguish the condition from other malignant processes, including melanoma or squamous cell carcinoma in situ.[3]

When Paget cells are noted in the epidermis, cytokeratin (CK)–7 and CK20 can be extremely helpful in characterizing the diagnosis. CK7 is extremely sensitive (though poorly specific) in identifying EMPD cells. Cancers of the urothelial and gastrointestinal tracts, which can show pagetoid spread, strongly express CK20, while EMPD does not. It follows that primary EMPD typically stains positive for CK7 and negative CK20, while secondary EMPD stains positive for both.[23] When the diagnosis remains in doubt, gross cystic disease fluid protein 15 (GCDFP-15) is another stain that shows specificity for secondary EMPD. Although unable to differentiate primary from secondary disease, epithelial membrane antigen (EMA), PAS, and carcinoembryonic antigen (CEA) stains are also sometimes used to identify Paget cells.[23] The dermatopathologist may select a combination of these stains in order to make the diagnosis.

More recently, studies on genetic and protein expression profiles of EMPD cells are providing useful prognostic information. HER2, Ki-67, cyclin D1, and MUC5AC are some of the more promising markers of tumor differentiation. In preliminary studies, expression of any or all of these markers has been associated with more aggressive tumors.[23] Owing to cost and access issues, routine use of these studies is not standard practice at this time.

Staging

TNM (tumor, node, metastasis) classification is used to describe many solid tumors and determine staging. Currently, no TNM staging system exists for extramammary Paget disease (EMPD). However, staging has been established for EMPD with perianal involvement and is as follows[24] :

  • Stage I: Paget cells located in perianal epidermis and adnexa without underlying carcinoma
  • Stage IIA: Cutaneous Paget disease associated with adnexal carcinoma
  • Stage IIB: Cutaneous Paget disease associated with anorectal carcinoma
  • Stage III: Paget disease associated with underlying carcinoma that has metastasized to nearby lymph nodes
  • Stage IV: Paget disease associated with underlying carcinoma that has distant metastases

A 2016 retrospective review of patients with EMPD proposed the staging system detailed below[25] :

  • Stage I: Tumor thickness less than 4 mm without lymphovascular invasion
  • Stage II: Tumor thickness greater than 4 mm or lymphovascular invasion
  • Stage IIIa: Any tumor thickness plus one regional lymph node metastasis
  • Stage IIIb: Any tumor thickness plus two regional lymph node metastases
  • Stage IV: Any tumor thickness plus distant organ metastasis or distant lymph node metastasis
 

Treatment

Approach Considerations

Owing to the rarity of extramammary Paget disease (EMPD), a wide range of optimal treatment modalities has not yet been defined. The first-line treatment has long been surgical excision. Successful treatment has been achieved with both wide local excision and Mohs micrographic surgery (MMS). Conservative treatments may be considered in patients who are poor surgical candidates. Topical therapy with chemotherapeutic agents 5-fluorouracil (5-FU), bleomycin, and imiquimod has been infrequently reported in the literature. In addition, radiation therapy and photodynamic therapy have been suggested as potential treatment options, although further studies are needed to determine the efficacy of these modalities for EMPD patients.[26] Treatment of underlying malignancy is also warranted in cases of secondary EMPD.

Surgical Excision

Margin-controlled surgical excision of all the involved epidermis is the current criterion standard treatment. Extramammary Paget disease (EMPD) frequently extends beyond the visibly involved margins. Obviously involved skin should be examined by using transverse frozen sections or serial vertical sections (see Workup). It has been suggested that multiple scouting biopsies performed before surgery may aid in planning a more precise initial excision.[11] However, a 2018 retrospective study found no utility for mapping biopsies with well-defined EMPD or when 2-cm margins could be achieved.[27]

Multifocal disease is a challenge for any surgical method that relies on contiguous tumor spread for effective margin control—even micrographic surgery. Currently, wide local excision and Mohs micrographic surgery (MMS) are the recommended excision options. The margin size for wide local excision has been debated in the literature. Some reports suggest using a margin extending 3-5 cm beyond the circumference of the tumor,[28, 29] while other data suggest a margin of 1 cm for lesions with clinically distinct margins.[30] When operating in the anogenital region, providers must consider the aesthetic and functional consequences patients may face after radical excision.

MMS offers lower recurrence rates after excision of primary tumors, with a smaller margin of normal skin removed.[28, 31] The reported recurrence rate of primary tumors after standard surgical excision ranges from 30-60%. The rate after excision with MMS ranges from 8-26%. A 2017 study found a recurrence rate of 11% after MMS of primary EMPD, compared with a 31% recurrence rate after standard excision.[32] MMS has also been shown to result in an over 10-fold reduction in the risk of positive margins as compared with wide local excision.[33] The use of intraoperative markers such as cytokeratin 7 (CK7) and carcinoembryonic antigen (CEA) during MMS has been suggested to improve visualization of Paget cells.[34, 35]

The average time to recurrence after excision is 2.5 years; however, cases have been reported with recurrence more than 10 years later. Although long-term outcomes are improved using MMS, some patients may not be able to afford the higher treatment costs.

Chemotherapy

Several studies have reported the topical use of chemotherapeutic agents including 5-fluorouracil (5-FU), bleomycin, and imiquimod to treat extramammary Paget disease (EMPD). 5-FU and bleomycin have shown poor response rates with toxic adverse effects, including allergic reaction, severe pain, and desquamation. A few studies have shown clinical resolution of patients treated with topical 5-FU; however, biopsy specimens were often found to reveal histologic persistence of disease.[36, 37, 38]

Imiquimod 5% cream applied 3 times weekly for 16 weeks was found to induce complete resolution in a patient with perineal EMPD.[39] Imiquimod has also been found to be effective in combination with other modalities. One case report describes two patients with recurrent and extensive EMPD achieving complete remission after 5-aminolevulinic acid (5-ALA) photodynamic therapy and topical imiquimod.[40] Lesions were treated with 20% 5-ALA photodynamic therapy every 2 weeks for a total of 6 cycles followed by topical imiquimod every other day for 3 months. Topical imiquimod is considered a possible treatment option, especially when surgery is a challenge or contraindicated. However, more studies are needed to confirm the use of topical therapies for patients with EMPD.[39] Topical treatments may also be effective when combined with photodynamic therapy, although this combination therapy needs to be studied in a larger patient population before definitive recommendations can be made.

Photodynamic Therapy

Photodynamic therapy may be a useful therapy for extramammary Paget disease (EMPD) confined to the epidermis as an adjunct to surgical treatment or as a primary therapy in patients who are poor surgical candidates. It is less invasive and can target large areas of skin in a single session. It has been used successfully to treat other superficial epidermal neoplasms such as actinic keratoses and superficial basal cell carcinomas, but has not yet been extensively studied as a treatment for EMPD.[26]

Radiation

Radiation therapy is a potential primary and adjuvant treatment option for extramammary Paget disease (EMPD) and has been shown to have a response rate ranging from 62-100%.[26] It can also be effective in the local control of in situ lesions in inoperable cases of EMPD.[41, 42, 43] However, there have been no randomized controlled trials comparing surgical excision and radiotherapy. Radiation also compromises the skin's ability to heal, making further treatment after recurrence in patients previously treated with radiation challenging.

Consultations and Long-Term Monitoring

Depending on the anatomic location of extramammary Paget disease (EMPD), treatment should be coordinated with an appropriate surgical subspecialist (eg, urologist, colorectal surgeon, gynecologist). Optimally, the consultant would have some experience treating this specific condition. Further consultation with a radiologist and a gastroenterologist may also be required to order appropriate screening examinations for internal malignancy.

Patients with EMPD require follow-up examination every 3 months after surgery to assess possible recurrence. This routine should continue for at least 24 months, after which time examinations may be done annually. Other endoscopic or imaging studies can be repeated on a regular basis according to the specific recommendations of the consultants.

A 2017 study found serum cytokeratin 19 fragment 21-1 (CYFRA 21-1) levels to be useful in monitoring tumor burden and treatment response. Compared with carcinoembryonic antigen (CEA) monitoring, CYFRA 21-1 levels were more sensitive in detecting tumor reduction as well as recurrence, with a corresponding decrease and increase in serum concentration, respectively.[44]

 

Medication

Medication Summary

Topical imiquimod and fluorouracil are considered as possible treatment options when surgery is a challenge or contraindicated. However, more studies are needed to confirm the efficacy of topical therapies for patients with extramammary Paget disease (EMPD).

Immunomodulators

Class Summary

These agents modulate key factors of the immune system.

Imiquimod (Aldara, Zyclara)

Imiquimod is an immune response modifier that induces apoptosis by binding to Toll-like receptors seven and eight on monocytes, macrophages, and dendritic cells. It is indicated to treat clinically typical, nonhyperkeratotic, nonhypertrophic actinic keratoses on the face or scalp.

Antineoplastics, Antimetabolite

Class Summary

These agents inhibit cell growth and proliferation.

Fluorouracil (Carac, Efudex, Fluoroplex)

Fluorouracil is used topically. It interferes with DNA synthesis by blocking methylation of deoxyuridylic acid via inhibition of thymidylate synthetase and, subsequently, cell proliferation.