Medullary carcinoma

Medullary carcinoma is a rare type of breast carcinoma, usually occurring in the fifth and sixth decade of life. It characteristically presents as a well-demarcated lesion. Medullary carcinoma has been thought to have a better prognosis than ductal carcinoma NOS, although some studies have suggested that this is not true.

Cytological diagnostic features

• High cellularity
• Syncitial aggregates and single cells
• High nuclear grade and high N/C ratio
• Bizarre pleomorphic cells
• Necrotic diathesis
• Lymphocytes and plasma cells

The admixture of lymphocytes and plasma cells is characteristic. The cytoplasm of malignant cells can be scanty to abundant, usually basophilic and finely granular or vacuolated. Multiple irregular macronucleoli can be observed. Stripped large bizarre nuclei can occasionally be present.
Although medullary carcinoma can be suspected, the final classification should rest on histological examination, as a number of breast carcinomas can have a prominent lymphoplasmacytic infiltrate.