Invasive breast carcinoma in a patient with PHTS: a case report.

Background: PTEN hamartoma tumor syndrome (PHTS) is a rare, multisystem disorder caused by germline pathogenic variants in the PTEN gene, predisposing individuals to various malignancies, including breast cancer.

Case presentation: We describe a 26-year-old woman with longstanding bilateral palpable breast masses and spontaneous bloody nipple discharge. Imaging revealed numerous cysts and masses, predominantly in the right breast. Multiple biopsies showed benign papilloma with focal atypical ductal hyperplasia (ADH), while total mastectomy specimens revealed multifocal, poorly differentiated, triple-negative invasive carcinoma. An axillary lymph node contained ectopic breast tissue with associated papillary proliferation. Genetic testing identified a pathogenic germline PTEN variant (c.209 + 4_209 + 7delAGTA), confirming PTEN hamartoma tumor syndrome (PHTS).

Conclusion: This case underscores the importance of considering PHTS in young patients presenting with extensive papillomatosis and other unusual breast pathologic findings, even in the absence of a family history of cancer. Early recognition enables timely genetic counseling, confirmatory testing, and implementation of appropriate surveillance and management strategies.