Bilaterality with medullary carcinoma of breast is seen in:

Medullary carcinoma is a special-type breast cancer; it accounts for 4% of all invasive breast cancers and is a frequent phenotype of BRCA1 hereditary breast cancer. Grossly, the cancer is soft and hemorrhagic. A rapid increase in size may occur secondary to necrosis and hemorrhage. On physical examination, it is bulky and often positioned deep within the breast. Bilaterality is repoed in 20% of cases. Ref: Schwaz's principle of surgery 9th edition, chapter 17.