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Ira J. Bleiweiss, MD

Professor of Pathology and Laboratory Medicine
Director, Breast Pathology Subspecialty Service
University of Pennsylvania, Perelman School of Medicine
Philadelphia, Pennsylvania

Current Research

  • Seeking to establish the unique biomarker patterns of breast cancers associated with uncommon genetic alterations.

  • Pathology review of tumor tissue from patients with and without BRCA2 mutations is conducted to detect unique patterns of protiens.

  • This work will help to identify characteristics of less common tumors that can help guide treatment choices and predict response to therapy.

Breast cancers harboring mutations in the BRCA1 gene often have unique histologic characteristics (what the pathologist sees under the microscope) that may alert clinicians to potential BRCA mutation in the tumor. The morphologies of BRCA2-associated cancers, however, are less well understood.

Dr. Bleiweiss and his team are conducting studies to characterize histology and biomarker patterns of BRCA2-associated cancers as well as non-BRCA-associated breast cancers (including the common markers: estrogen receptor, progesterone receptor, and HER2).

Results will allow better characterization of breast cancer subtypes and subsequent improvement in selection of therapies that are most likely to be effective.


Ira J. Bleiweiss, MD is a Professor of Pathology and Laboratory Medicine in the Perelman School of Medicine of the University of Pennsylvania.  He is director of the Breast Pathology Subspecialty Service at the Hospital of the University of Pennsylvania. Dr. Bleiweiss received his MD from St. Georges University School of Medicine, followed by residency in Anatomic and Clinical Pathology and fellowship in Surgical Pathology at The Mount Sinai Medical Center. After fellowship at Memorial Sloan Kettering Cancer Center, Dr. Bleiweiss returned to Mount Sinai, Department of Pathology to become Professor, Director of Surgical Pathology and Director of Anatomic Pathology. With more than 25 years of experience he oversees a completely subspecialized service dedicated to diagnosing breast lesions in specimens from hospital, as well as private practice outpatient settings.

Dr. Bleiweiss is well-known nationally and internationally for his expertise in breast pathology and is the author of more than 100 peer reviewed publications, largely related to breast cancer, many in the area of radiologic-pathologic correlation of image-guided breast core biopsies, a subject on which he co-authored a textbook.

His focus is distinctly multidisciplinary, and he is the current President of the International Society of Breast Pathology.

BCRF Investigator Since


Donor Recognition

The Women's Cancer Research Fund Award

Area(s) of Focus