Mass-forming Acellular Keratin Masquerading as "Residual Tumor" in a Metaplastic Breast Carcinoma with Pathologic Complete Response: A Case Report.
Angelica Ms Caindec, Linda C Hanley, Kamaljeet Singh
✦ AI-curated · Sources linked
Case in brief
A patient with metaplastic breast carcinoma showing squamous differentiation received neoadjuvant chemotherapy. Although a mass remained palpable and visible on ultrasonography after treatment, examination of the tumor bed found keratinous debris but no viable residual tumor, consistent with a pathologic complete response. The persistent mass therefore suggested incomplete response clinically despite the absence of residual carcinoma pathologically.
What made this case unusual
Acellular keratin persisted as a mass on examination and ultrasonography, mimicking residual tumor despite pathologic complete response.
Diagnostic / clinical pearl
In treated metaplastic breast carcinoma with squamous differentiation, a persistent mass may consist of acellular keratin rather than viable tumor; correlate clinical and imaging findings with tumor-bed pathology.