- 73 year old female presented with an erythematous, scaly, and eroded plaque on the right nipple.
- No personal or family history of breast cancer.
- Physical examination failed to reveal a palpable breast mass.
- Biopsy was performed after the lesion was unresponsive to topical corticosteroids.
- Irritant contact dermatitis
- Mammary Paget disease
- Squamous cell carcinoma
- There is a proliferation of enlarged epithelioid cells distributed at all levels of the epidermis in pagetoid array with abundant vacuolated cytoplasm.
- The tumor cells exhibit nuclear pleomorphism and atypical mitotic figures are present.
- Positive for EMA and Cam5.2
- Negative for p63, estrogen receptor (ER), progesterone receptor (PR), and mucicarmine
Histologic Differential Diagnosis:
- Mammary Paget disease
- Squamous cell carcinoma in situ with Bowenoid features
“Anaplastic” Mammary Paget Disease
- This variant of mammary Paget disease shows striking cytologic atypia and mimics pagetoid Bowen disease histologically.
- The tumor cells in mammary Paget disease typically show positive staining for CEA, EMA, CK7, Cam5.2 and cytokeratin AE1/AE3.
- The anaplastic variant of mammary Paget disease is often negative for mucin special stains (such as Alcian blue and mucicarmine), which was seen in our case.
- While CK7 is often positive in mammary paget disease, it may also be positive in a subset of squamous cell carcinomas.
- Some examples of anaplastic mammary Paget disease also show acantholysis.
- Clues to the diagnosis of anaplastic mammary Paget disease include the absence of dyskeratotic cells and desmosomes, presence of intracellular mucin/signet ring cells, and positive staining for CEA and EMA.
What is this tumor, and why should I know about it?
- Anaplastic mammary Paget disease can mimic pagetoid Bowen disease histologically.
- The anaplastic variant of mammary paget disease may be associated with an increased risk of underlying invasive carcinoma, even in the absence of a palpable mass.
- Anaplastic Paget disease mimics pagetoid Bowens disease histologically.
- This variant is negative for mucin special stains (Alcian blue and mucicarmine) and may show acantholysis.
- Positive staining for CEA and EMA favor a diagnosis of anaplastic mammary Paget disease over pagetoid Bowen disease.
- Even with the absence of a palpable mass, anaplastic mammary Paget disease may be associated with increased risk of an underlying invasive breast cancer compared to conventional Paget disease.