BREAST CYTOPATHOLOGY

134 4. Primary Malignant Tumors
Clinical Features
• Rare tumors, less than 1% of all breast tumors
• Initially present as discrete palpable masses that may show
rapid enlargement
Cytomorphologic Characteristics
• Variable
Pitfalls and Differential Diagnosis
• Variable
Leiomyosarcoma
Clinical Features
• These primary smooth muscle tumors of the breast are
rare, comprising less than 1% of all breast tumors.
• They arise most commonly from the smooth muscle of the
nipple and areola.
• Leiomyosarcomas arise within the breast as well. Both present
as slowly growing, palpable masses that may be painful.
Cytomorphologic Characteristics
• Variable cellularity
• Dissociated cells with sheets of spindle and round cells
• Increased mitotic activity, prominent nuclear atypia, and
necrosis
Pitfalls and Differential Diagnosis
• Phyllodes tumor
• Metaplastic carcinoma
• Hemangiopericytoma
• Fibromatosis
Selected Reading
Cai G, Simsir A, Cangiarella J: Invasive mammary carcinoma with
osteoclast-like giant cells diagnosed by fine-needle aspiration