Ectopic extramammary Paget disease in thoracic location

Area of Science:

• Dermatology
• Oncology
• Pathology

Background:

• Extramammary Paget disease (EMPD) is a rare skin malignancy originating in apocrine gland-rich areas.
• Ectopic extramammary Paget disease (E-EMPD) is an uncommon variant occurring outside typical sites.
• Few cases of E-EMPD have been documented globally.

Observation:

• A 55-year-old male presented with a year-long history of an asymptomatic thoracic plaque.
• The lesion appeared as a soft, reddish-pink patch with hyperkeratosis and erosion.
• Clinical presentation suggested a dermatological condition requiring further investigation.

Findings:

• Histological examination and immunohistochemistry confirmed primary ectopic extramammary Paget disease.
• Immunohistochemical staining was crucial for diagnosing a primary neoplasm without an underlying malignancy.
• This represents the first confirmed Latin American case of primary E-EMPD.

Implications:

• Highlights the importance of immunohistochemistry in diagnosing E-EMPD.
• Expands the known geographical distribution of E-EMPD cases.
• Contributes to the limited case reports of this rare ectopic skin cancer.