CASE OF THE MONTH
Paget Disease of the Breast
Paget disease is an uncommon skin manifestation of breast cancer, associated with either invasive carcinoma or ductal carcinoma in situ in the underlying breast. It is present in 1-4% of all patients with breast carcinoma. Nipple skin with scaling crust, possible ulceration, and erythema and exudate resembling chroniceczema (see photo - not from patient) is usually present.
The present case is of a 61 year old female who presents with skin rash around the right nipple of about one year duration. Previous punch biopsy a year ago was negative. The present punch biopsy shows a skin lesion characterized by atypical single cells or cluster of cells spread throughout the epidermis. These cells have abundant pale cytoplasm, irregular large nucleus with prominent nucleoli. The overlying skin showed hyperkeratosis and ulceration.
The differential diagnosis in this case is between melanoma-in-situ, carcinoma-in-situ and Paget disease. The Melan-A immunohistochemical stain was negative; CK7 and HER2 were diffusely positive (see images). These results are diagnostic of Paget disease.
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