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Taniguchi, Kohei Department of Pathology, Okayama University Hospital
Takada, Shinichi Department of Pathology, Yuai Memorial Hospital
Omori, Masako Department of Pathology, Kurashiki Medical Center
Igawa, Takuro Department of Pathology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Science
Nishimura, Midori Filiz Department of Pathology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Science
Morito, Toshiaki Department of Pathology, National Hospital Organization Iwakuni Clinical Center
Ichimura, Kouichi Department of Pathology, Hiroshima City Hiroshima Citizens Hospital
Pleomorphic lobular carcinoma (PLC) is a histological variant of invasive lobular carcinoma (ILC) and is associated with worse prognosis than classical ILC. It exhibits a greater degree of cellular atypia and pleomorphism and is occasionally accompanied with apocrine morphology. We investigated the immunohistochemical characteristics of samples from 31 Japanese patients with PLC to elucidate the clinicopathological characteristics of PLC including androgen receptor (AR) immunoreactivity. The surrogate molecular subtypes were luminal A-like, luminal B-like, luminal B-like/HER2, HER2-type, and triple-negative in 5, 4, 3, 5, and 14 cases, respectively. AR was positive in 92.8% (13/14) of the triple-negative PLC cases and 100% (10/10) of the non-triple-negative PLC cases. Disease-specific survival was worse in patients with histological grade 3 PLCs than in those with histological grade 2 PLCs (p = 0.007). However, there was no significant difference in the progression-free survival between the two groups (p = 0.152). No other clinicopathological characteristics were associated with prognosis. These results reveal that PLC exhibits various surrogate molecular subtypes and that the triple-negative subtype frequently expresses AR. The observed molecular apocrine differentiation implicates that triple-negative PLC can be categorized into the luminal AR subtype. Furthermore, AR-targeted therapy might be useful for patients with triple-negative PLC.
Public Library of Science
© 2020 Taniguchi et al.
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