•  This high power view shows the cytologic features of lobular carcinoma.

•  The cells have oval to round nuclei and may be "signet ring" (arrows) with a vacuole of mucin forming the hole in the center of a ring and the nucleus bulgin to form the seal or stone in the ring.

•  The linear pattern of infiltration is also known as "indian filing".

• Unknown

• Unknown

•• BRCA1 mutations

• Between 3-14% of invasive carcinomas of the breast depending on microscopic criteria for diagnosis

• More common in older women with breast cancer

• Present as palpable or mammographic mass, but some because of little desmoplasia may be very subtle

• Bilaterality ranges from 6-28%

• Neoplasms spread to axillary lymph nodes and then disseminate to peritoneal surfaces, meninges, ovaries and uterus in a somewhat different pattern than ductal carcinoma, similar to the pattern in signet ring carcinoma of the gastrointestinal tract

• Therapy dependent on stage with treatment similar to that with invasive duct carcinoma

• Usually low grade, estrogen and progesterone receptor positive and Her2/neu negative.

• Loss of region of chromosome 16 that includes genes for cell adhesion molecule e-cadherin

•For more information on prognosis and treatment, consult the NCI web site.

Visit National Cancer Institute for Current Treatment

• Mass may be firm to hard or not readily palpable or visible

• May be detected mammographically, although microcalcifications are uncommon

• Neoplastic cells infiltrate in small linear groups: "Indian file"

• Circle around preexisting benign ducts forming a "target"

• Some variants are recognized with solid, tubulolobular or alveolar patterns

• Intracytoplasmic lumens may be identified by electron microscopy

• Mucin vacuoles creating a signet ring appearance with a nucleus pressed against the cytoplasmic membrane by a large mucin vacuole may be seen.

• Robbins and Cotran: Pathologic Basis of Disease, 7th ed., 2005, pp. 1144-45.

• Current literature from PubMed at National Library of Medicine