Spindle cell lesions of the breast - An approach to diagnosis

Spindle cell lesions of the breast are among the less common entities encountered in breast pathology. They encompass a whole spectrum of benign reactive lesions to high grade malignant neoplasms. An accurate diagnosis is important to ensure that the patient receives the appropriate management. While this group of conditions broadly share the same basic morphology of a lesion composed of spindle cells, there are often recognizable differences on histology, which coupled with ancillary studies and correlation with the clinical and imaging findings, can help one to arrive at a specific diagnosis. On core biopsy however, spindle cell lesions pose significant interpretive challenges and a firm diagnosis is often not possible. We share our approach to this group of conditions, with a focus on the more common entities, highlighting their key clinical, imaging and pathological features.