A case report of pleomorphic invasive lobular carcinoma diagnosed following longitudinal imaging changes in a breast abnormality

Invasive lobular carcinoma (ILC) is often difficult to diagnose because of subtle imaging findings and potential false-negative biopsy results due to its infiltrative growth pattern. A 30-year-old woman was referred for evaluation of breast asymmetry. Ultrasonography demonstrated an indistinct hypoechoic area, and ultrasound-guided core needle biopsy (16-gauge, four cores) demonstrated fibrocystic changes without atypia. She did not undergo routine screening thereafter. At age 42, screening mammography prompted re-evaluation; repeat ultrasound-guided core needle biopsy again demonstrated fibrocystic changes without atypia. At age 44, screening ultrasonography revealed increased lesion thickness, an elevated depth-to-width ratio, and newly detected internal vascularity. Vacuum-assisted biopsy targeting the central portion of the lesion revealed pleomorphic invasive lobular carcinoma with complete membranous loss of E-cadherin expression. Retrospective re-review of prior biopsy specimens confirmed no evidence of invasive carcinoma, LCIS, or ALH. The patient remained free of recurrence three years after surgery This case illustrates the diagnostic complexity of ILC. Progressive imaging changes should prompt renewed imaging–pathology correlation and, when clinically appropriate, consideration of repeat biopsy despite prior benign biopsy results.