Imaging and Clinicopathological Features of Squamous Cell Metaplastic Breast Carcinoma: A 22-Case Retrospective Study

Background/Objectives: Squamous cell metaplastic breast carcinoma (SCMBC) is a rare and aggressive breast cancer subtype with limited imaging and prognostic data. This study aimed to characterize the multimodal imaging features, clinicopathological profiles, and prognostic outcomes of SCMBC in a single-center cohort. Methods: We retrospectively analyzed 22 patients with histopathologically confirmed SCMBC treated between January 2012 and May 2025. Clinicopathological profiles, multimodal imaging features, and prognostic outcomes were collected and evaluated. Results: All patients were female (median age 64.5 years; range, 34-82). The majority (59.1%) presented with clinical stage II disease. Axillary lymph node metastasis was present in eight (36.4%) patients at diagnosis, with one case of distant lung metastasis. The mean tumor diameter was 4.24 cm (range, 2.1-11.8). MRI findings (n = 13) included heterogeneous internal structure, a low mean apparent diffusion coefficient (ADC) value of 0.98 × 10^-3 mm²/s, and frequent necrosis (92.3%). Pathologically, 54.5% of tumors were high-grade, and 81.8% exhibited a triple-negative phenotype. After a median follow-up of 34 months, the 5-year overall survival (OS) rate was 64.3%, while the 3-year disease-free survival (DFS) rate was 42.1%. The recurrence/metastasis rate was 22.7% (5/22), and all five deaths occurred in this subgroup. Conclusions: SCMBC is characterized by suggestive multimodal imaging features, a predominant triple-negative phenotype, and a high risk of early recurrence. Given the exploratory nature of this single-center study with a limited sample size, these findings require validation in larger, prospective cohorts. Early radiological identification and aggressive personalized treatment strategies may improve outcomes for patients with this aggressive disease.