Pleomorphic lobular carcinoma of the breast: a comparison of cytopathological features with other lobular carcinoma variants.

Objective: Pleomorphic lobular carcinoma (PLC) is a subtype of breast cancer with unique morphological features, but it remains controversial whether PLC should be considered an independent disease entity. The aim of this study was to illustrate cytopathological characteristics of PLC in comparison with other lobular carcinoma variants. Methods: We investigated clinicopathological features of PLC (n = 11) compared with those of other variants of invasive lobular carcinoma (ILC, non-PLC) (n = 32). Histological variants of the non-PLC group consisted of classic (n = 25), solid (n = 2), alveolar (n = 1) and a tubulolobular type (n = 4). A review of cytological reports and fine needle aspiration (FNA) smear samples was performed for the PLC (n = 9) and non-PLC (n = 27) groups. Results: : Patients with PLC were older, and had a higher nuclear grade and a higher incidence of axillary lymph node metastasis and triple negative phenotype than non-PLC patients (P = 0.007, P < 0.001, P = 0.02 and P < 0.001, respectively). Cytological findings in PLC included medium-to large-sized nuclei, prominent nucleoli, a moderate-to-severe degree of pleomorphism, apocrine change and background necrosis, none of which were evident in the smears of the non-PLC group (P < 0.001, P = 0.002, P < 0.001, P < 0.001, and P = 0.03, respectively). Despite these differences, patients with PLC and non-PLC showed similar clinical outcomes in our follow-up period. Conclusions: Based on our results, a cytological diagnosis of PLC should be proposed if there are moderate-to large-sized nuclei, prominent nucleoli, a moderate-to severe degree of nuclear pleomorphism, apocrine change and necrosis in the background in FNA biopsy samples.