by Chase A. Scarbrough, DO; Abby Vrable, DO; and David R. Carr, MD

Drs. Scarbrough and Carr are with the Division of Dermatology at the Ohio State University in Columbus, Ohio. Dr. Vrable is with the Department of Dermatology at Boston Medical Center in Boston, Massachusetts. 

FUNDING: No funding was provided for this study.

DISCLOSURES: The authors have no conflicts of interest relevant to the content of this article.

ABSTRACT: Background.Extramammary Paget’s disease (EMPD) is a rare neoplasm that affects apocrine gland-bearing skin. Patients usually present with a long-standing, unilateral, ill-defined, erythematous, crusted patch or plaque. In certain cases, this disease can be associated with internal malignancy. EMPD arising in anatomic areas devoid of apocrine glands is exceedingly rare and is termed ectopic extramammary Paget’s disease (E-EMPD).

Objective.We discuss the classification, origin, and management of E-EMPD.

Methods.We reviewed the literature and herein discuss the reported cases of true E-EMPD.

Discussion. Forty-five cases of E-EMPD disease were identified in the literature. The etiology and pathophysiology are largely unknown. Based on there only being one reported case of lymph node metastasis and associated underlying malignancy identified, compared to EMPD, ectopic lesions appear to be less aggressive. Various treatment options have been reported, with surgical removal being the preferred method of treatment.

Conclusion: E-EMPD is a rare neoplasm that manifests in areas without apocrine glands. With adequate formal data unavailable, the authors recommend that a diagnosis of E-EMPD warrants a focused malignancy screening. Surgical excision is the most common first-line treatment. Further research is needed regarding the etiology, biologic behavior, and treatment of E-EMPD.

KEYWORDS: Ectopic extramammary Paget’s disease, extramammary Paget’s disease 

 J Clin Aesthet Dermatol. 2019;12(8):40–44


Extramammary Paget’s disease (EMPD) is a rare form of adenocarcinoma that affects apocrine gland-bearing skin. Ectopic-EMPD (E-EMPD) is the term used when EMPD lesions are located in areas void of apocrine glands,1 and this condition is rarely reported in the literature. Clinically and histologically, ectopic extramammary Paget’s disease (E-EMPD) and classic EMPD have similar presentations, except for the location of the disease. While previous literature classifies, defines the origin, and discusses treatment modalities for EMPD, special consideration is needed to standardize these data and determine if a separate approach is needed for E-EMPD. In this article, we review the available literature on E-EMPD in an effort to determine disease definition, typical characteristics of presentation, theories of development, associations with malignancies, biologic activity, and effective treatment options.

methods

A comprehensive literature search was performed using PubMed, CINAHL, and Medline databases to identify reported cases of E-EMPD. Individuals that met the following criteria were included in the case group: 1) presence of ectopic extramammary paget’s disease; and 2) the anatomic locations of reported cases were located on the scalp, face, chest, abdomen, back, buttocks, arms and legs. Reports were carefully reviewed to ensure that lesions deemed ectopic were in areas without apocrine glands. The anatomic locations of reported cases used in this review were the scalp, face, chest, abdomen, back, buttocks, arms, and legs.1,3–31,33–35,38,40,41,50–58 Associated malignancies, treatments, and outcomes were also considered. The content was evaluated for relevance, and 45 reports of E-EMPD were referenced and organized based on presentation, location, associated malignancy, treatment, and outcome.

results and discussion

To date, there have been only 45 documented cases in the literature, albeit presenting in a wide variety of anatomic locations, as follows: chest, abdomen, back, buttocks, face, scalp, and legs.1,3–31,33–35,38,40,41,50–58 

As EMPD is more common than E-EMPD, it has been described in much greater depth in the literature. Due to similarities in clinical appearance and histopathology, many of the attributes of EMPD have been ascribed to E-EMPD. As EMPD can be associated with underlying malignancies, dermal invasion, and metastasis, it is important to further define the entity of E-EMPD for appropriate risk-stratification and treatment of these patients. 

Definition. Based on our review of the literature, E-EMPD is defined as an adenocarcinoma that is similar in histopathologic appearance to EMPD, but located in an area devoid of apocrine glands (genital skin and axillae) or modified apocrine glands (i.e., the germinative milk line, ceruminous glands of the ears, and Moll’s glands of the eyelids). The germinative milk line is defined as a narrow band-like thickening of the ectoderm extending over each side of the ventral surface of the embryo.1 The breast is usually restricted to the chest wall; however, supernumerary areolae and breasts are known to occur in 1 to 6 percent of the population.2 Most aberrant breast tissue is found along the germinative milk line, most commonly in the axilla.3 It is important when evaluating suspected cases of E-EMPD that the lesions do not encompass an area where apocrine, modified apocrine, or aberrant apocrine glands are located. 

Presentation. To date, there have been 45 reported cases of E-EMPD. E-EMPD appears to be more common among Asian patients, with 64 percent of reported cases being in the Asian population (Table 1).1,4–31 Clinically and histologically, E-EMPD and the more common EMPD have similar manifestations except for location of the disease. Both E-EMPD and EMPD typically present initially as a velvety, soft, red or bright pink patch or plaque with scattered white islands of hyperkeratosis and erosion, often referred to as a “strawberries and cream” appearance. Up to 64 percent of patients present with pruritus at initial presentation, and it is the most common associated symptom.32 The differential diagnosis of E-EMPD can be vast, including eczema, cutaneous fungal infections, contact dermatitis, squamous cell carcinoma, Bowen’s disease, basal cell carcinoma, melanoma, and mycosis fungiodes.33 Often, diagnosis is further delayed due to initial clinical misdiagnosis and extended periods of topical or systemic management before biopsy is performed.34 Data from case studies document varying periods of time to diagnosis, ranging from eight months to more than 30 years.31,35

Apocrine and eccrine gland origin theory of development. As E-EMPD occurs on apocrine-poor or apocrine-free regions, it is unlikely that E-EMPD is derived from apocrine glands. Although immunohistochemical analyses are useful to differentiate the apocrine gland from the eccrine gland, precise determination of tumor origin is still difficult in sweat gland neoplasms.1 Gross cystic disease fluid protein-15 (GCDFP-15) is a useful marker in identifying tumors of apocrine origin. However, a study by Viacava et al36 showed GCDFP-15 positivity among cutaneous eccrine glands as well, making the precise derivation of E-EMPD unclear. This raises the possibility that E-EMPD might be a subset of EMPD that arises from GCDFP-15-positive eccrine glands. 

Pluripotential germinative cells theory of development. This theory is based on the idea of pluripotential germinative cells that, when exposed to any number of carcinogenic factors, can produce a cancerous form of apocrine or eccrine glands. Jones et al33 studied 55 cases of EMPD histopathologically, including one ectopic case. They proposed the existence of pluripotential germinative cells within the epidermis as the origin of Paget’s cells. These cells are thought to be able to differentiate not only into apocrine glands, but also eccrine glands.13 With exposure to certain carcinogenic factors, these cells could go on to produce the Paget cells of both E-EMPD and EMPD.33 This theory helps to explain the existence of E-EMPD in areas void of apocrine glands.

Association with malignancy. The association of EMPD with underlying malignancies and the associated poorer prognosis makes the determination of primary (i.e., no associated underlying malignancy) and secondary (i.e., associated with an underlying malignancy) EMPD very important. 

EMPD might be associated with other malignancies. Chanda et al37 studied 197 patients and found the incidence of underlying adnexal carcinoma to be 24 percent and the incidence of concurrent internal malignancy to be 12 percent. Other studies have reported associated adnexal cancers in 4 to 33 percent of cases and concurrent internal malignancies in 20 to 33 percent of cases.38 Hence, a metastatic examination is necessary. For each case, a full skin examination and palpation of draining lymph node basins is recommended. Based on patient characteristics, a chest X-ray, rectal examination, sigmoidoscopy, and cystoscopy might also be considered. Additionally, a pelvic exam with a Pap smear, pelvic ultrasound scan, hysteroscopy, laparoscopy and/or an magnetic resonance imaging scan of the pelvis and mammogram should be considered in women if necessary.39 In those cases associated with an underlying neoplasm, the anatomic location of the EMPD plaque often predicts the location of the underlying malignancy.38 This concept should be considered when choosing the appropriate work-up for each case. Finding an underlying primary malignancy in patients with EMPD is important when considering the treatment modality. When associated with either adnexal or internal malignancy, the prognosis of EMPD is significantly worse. The mortality rate in patients with EMPD and underlying adnexal carcinoma is reported to be 46 percent or higher as compared with 18 percent in those without underlying cancer.38

The risk of an associated malignancy with E-EMPD is not well-known. Only two reported cases of E-EMPD have been shown to be possibly related with internal malignancy. One case reported E-EMPD of the lateral thigh arising in association with a sweat gland carcinoma of the same area. Metastatic disease was also present in the left inguinal lymph nodes.34 The vacuolated epidermal cells, intradermal tumor cells, and metastatic tumor cells within the inguinal nodes all reacted with carcinoembryonic antigen. The similar immunostaining pattern of the primary sweat gland carcinoma and the overlying E-EMPD suggest that the epidermotropic cells were directly associated with the underlying sweat gland carcinoma. The other reported case was of a woman with an underlying colon adenocarcinoma who presented with a lesion of E-EMPD in the midline of the abdomen, above the umbilicus. Immunohistochemical stains demonstrated the lesion was CK7+/CK20-, which differed from the immunophenotype of the patients with underlying colon adenocarcinoma (CK7-/CK20+). Because of this, the authors argued against an association between the two processes.40 This suggests that immunohistochemical studies could be of great value if a patient has a visceral malignancy to determine whether the E-EMPD is a primary cutaneous lesion or represents a direct extension or ectopic focus of the underlying cancer. 

With little evidence linking E-EMPD with associated malignancies, it is difficult to determine if a specific work-up is necessary. As there are few cases of E-EMPD reported in the literature, it is prudent to follow the protocol established for EMPD, which can include abdomen/pelvis imaging, chest X-ray, mammography, positron-emission tomography scan, colonoscopy, cystoscopy, and/or pelvic examination. As always, considerations must be established in a unique fashion for each individual case. It appears as though rates of associated malignancies are lower in E-EMPD than in EMPD. Further research examining the association of E-EMPD with underlying malignancies is needed in order to accurately define an appropriate standardized work-up.

Biologic activity. Similar to the above section on the association with underlying malignancy, more data are available on the biologic activity of EMPD. Of note, the immunologic profiles of EMPD and E-EMPD might help provide insight into the biologic activity of these tumors. Of particular interest are the presence or absence of receptor activator of nuclear factor kappa-B ligand (RANKL) and matrix metalloproteinase 7 (MMP7). RANKL stimulates a release of cells that maintain an immunosuppressive tumor microenvironment. In addition, MMP7 has been associated with an increased risk of metastasis in certain tumors. Traditional EMPD has shown positivity to both RANKL and MMP7. This finding is clinically relevant in the numerous documented cases of metastatic EMPD. Hagiwara-Takita et al41 presented a case of E-EMPD on the lower abdomen of a patient that expressed RANKL but not MMP7. The immunological profile of this case suggests that E-EMPD is immunologically similar to EMPD, with respect to the expression of RANKL, but might carry a lower risk of metastasis with the absence of MMP7. To date, there has only been one documented case of questionable metastatic E-EMPD (discussed earlier). Since this report represents a single case, further analysis of the immunological profile of EMPD and E-EMPD are needed to better understand the biology of these tumors.

The biologic activity of EMPD has been associated with multiple factors, including depth of invasion, extracutaneous involvement, and genetic profile of the tumor.42 EMPD is considered microinvasive when Paget cells invade only into the papillary dermis. When the amount of dermal invasion goes beyond this, it is labeled as deeply invasive.43 A study of 76 patients with EMPD found that 29 percent of cases had microinvasion and 14 percent were classified as having deep invasion.44 Multiple studies have shown a poorer prognosis with deeply invasive EMPD.45,46 The difference in prognosis between noninvasive (in-situ disease) and microinvasive disease is less clear, with some studies showing a significant association with a poorer prognosis, and others not.42 Multiple studies have shown a much poorer prognosis with extracutaneous involvement, which is most commonly present in the lymph nodes.44,45,47,48 Finally, the genetic profile of EMPD can also portend a worse prognosis. For example, the sum of the tumor proliferation markers Ki-67 and Cyclin-D were found to be significantly higher in invasive lesions of EMPD compared to in in-situ lesions.49 

Conversely, the biologic activity has yet to be determined, and little is known regarding E-EMPD. No reports of dermal invasion were noted among the cases reviewed in the literature, suggesting E-EMPD might have a more benign biological activity. Only one case has been reported with lymph node invasion, and this case was associated with an underlying sweat gland carcinoma (discussed previously).34 No cases with distant metastasis were identified in the literature. Though more research is needed regarding the biologic activity of E-EMPD as it relates to invasion, lymph node metastasis, and distant metastasis, E-EMPD appears to have a favorable prognosis.

Treatment modalities. For EMPD and E-EMPD, reported treatment modalities include conventional surgical excision, Mohs micrographic surgery (MMS), topical immunotherapy, and photodynamic therapy (PDT). Modalities such as radiation, topical chemotherapy, systemic chemotherapy, and laser surgery have only been reported in EMPD. 

Surgical treatments. Surgical excision with wide margins and MMS are the most widely accepted forms of therapy for E-EMPD. The multicentricity and irregular histologic margins that extend beyond the clinically apparent lesion must be taken into account when choosing the most appropriate therapy. Most reports recommend a 2 to 3cm margin of normal skin when performing wide-margin excision.6,13,19,25,41,50,51 In one reported case, the surgeon performed an excision with a 5mm margin with subsequent treatment utilizing imiquimod 5% for five days weekly for 30 days with no recurrence at 24 months.52 There are four reports citing MMS as a treatment option for E-EMPD,35,38,53,54 one in which there was recurrence at eight months post-MMS, which was subsequently excised.38 Though available reports are limited, wide local excision with a 2 to 3cm clinically clear margin or MMS is recommended. 

Nonsurgical treatment. Nonsurgical therapy options have also been reported. Cordoba et al55 discussed the use of PDT in the treatment of E-EMPD on the temple. They prescribed two sessions of methyl aminolevulinate (MAL) PDT separated by one week. A good response was noted initially, but the lesion recurred at 18 months. A second round of two sessions of MAL-PDT was prescribed and resulted in a partial response, which led to the initiation of imiquimod.55 Likewise, Youssef and Reygagne56 reported the use of MAL-PDT for a lesion of E-EMPD on the scalp. MAL-PDT was applied to the area with a 1.0-cm clinical margin, allowed to soak for three hours, and then exposed to 37J/cm2 of visible red light. The patient was treated with three PDT sessions administered at four-week intervals. Complete remission was observed at three months and a complete clinical response was maintained at 12 months.

Topical immunotherapy with imiquimod 5% cream has been reported. While imiquimod 5% cream has been used as an adjuvant therapy postsurgically for E-EMPD,52 there is only one reported case using imiquimod as the primary treatment of double E-EMPD on the bilateral chest. Imiquimod 5% monotherapy was used for almost one year, with incomplete resolution of the lesions.21 Though data are limited on the use of imiquimod 5% in the treatment of E-EMPD, this case suggests that imiquimod might not be effective as a monotherapy.

Summary

E-EMPD is a rare neoplasm that manifests in areas void of apocrine glands. Its clinical presentation is indistiguishable from that of EMPD, except for its location. The etiology and pathogenesis for E-EMPD are still largely unknown. Preliminarily, E-EMPD appears to have a more benign biologic activity compared to EMPD, with only one case identified in the literature of lymph node metastasis and association with underlying malignancy. With formal data lacking, we recommend that the treatment plan for E-EMPD include a focused malignancy screening. Surgical excision with wide local excision and MMS are the most common first-line treatments. Further research is needed regarding the etiology, biologic behavior, and treatment of E-EMPD.

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