BREAST CYTOPATHOLOGY

Metastatic Tumors 143
• The most common metastasis is from the contralateral
breast.
• Virtually any malignancy may metastasize to the
breast.
• The most common metastatic tumors of the breast are lung
and malignant melanoma followed by ovary, kidney,
thyroid, cervix, stomach, and prostate.
• In children and adolescents, rhabdomyosarcoma represents
a common source of metastatic disease.
• Metastasis from other sites has also been reported.
• In men, prostate cancer is the most common form of metastatic
tumor to the breast.
• Tumors are usually well circumscribed and freely mobile
in the deep breast tissue.
• They are rarely predominantly cystic masses.
• Metastatic tumors may be multinodular and bilateral.
• Clinically, radiologically, and cytopathologically, metastatic
tumors may mimic primary breast carcinomas.
• Sarcomas can also occur as a primary breast carcinoma or
a metastasis from the other sites.
• Axillary lymph nodes are frequently involved.
• The most common locations for metastatic tumors are in
the upper outer quadrant.
• Microcalcifications are extremely rare in metastatic breast
carcinomas and have been described rarely in cases of
metastatic carcinomas of ovarian origin produced by psammoma
bodies.
Cytomorphologic Characteristics
(Figures 5.6 to 5.15)
• Characteristics depend on the type of primary tumor.
• Usually the aspirates from metastatic tumors present with
rich cellularity.
• If the cytomorphologic appearance is not that of a primary
breast carcinoma, other diagnostic possibilities including
metastatic disease must be entertained.