Mammary Paget Disease : Microscopic
Microscopic Features of Mammary Paget Disease (PD): The involved skin shows acanthosis and hyperkeratosis. There may be erosion or ulceration as well. Infiltrating the entire thickness of epidermis are large pleomorphic, malignant Paget cells that are scattered singly in a buckshot pattern, arranged in clusters and nests, or as solid sheets. The tumor cells may extend into the adnexal structures. Some cases show an acantholytic pattern. Paget cells have voluminous clear, pale eosinophilic or foamy cytoplasm. Glandular and acinar structures and signet ring cells with intracytoplasmic mucin may be present. There are no intercellular bridges. The nuclei are large and vesicular with prominent nucleoli. Mitotic activity is increased. The underlying dermis may show capillary telangiectasia and lympho-histiocytic infiltrate. Some cases of PD demonstrate prominent anaplasia. These so-called anaplastic variants of PD may be mistaken for Bowen disease. However, Bowen disease of nipple is exceedingly rare. More than 90% of PD cases are associated with invasive carcinoma of ductal type.