BREAST CYTOPATHOLOGY

Reactive Spindle Cell Nodules
Reactive Spindle Cell Nodules 55
Reactive spindle cell nodules are uncommon, benign, nonneoplastic
lesions that arise following FNA procedures. The
needle trauma to certain breast lesions incites a localized
myofibroblastic proliferation suggesting an exuberant reactive
response as a cause for reactive spindle cell nodules.
Clinical Features
• Most present as unencapsulated tiny nodules measuring up
to 10 mm in size.
• Interestingly, most reactive spindle cell nodules are seen in
association with papillary and complex sclerosing breast
lesions.
Cytomorphologic Characteristics
• Morphologically, the lesions in the breast are similar
to those seen in thyroid, salivary glands, and urinary
bladder.
• Smears show spindled cells with mild pleomorphism.
• Fine arborizing capillary vessels are present.
• Inflammatory cells and macrophages are present.
• Immunoexpression of smooth muscle markers is diagnostically
helpful.
Pitfalls and Differential Diagnosis
• Myofibroblastoma
• Pseudoangiomatous stromal hyperplasia
• Metaplastic carcinoma
Selected Reading
Allen EA, Parwani AV, Siddiqui MT, Clark DP, Ali SZ.: Cytopathologic
findings in breast masses in men with HIV infection. Acta
Cytol 2003, 47:183–187.