About Peter Sadow, MD, PhD

Dr. Sadow, Director of Head and Neck Pathology, is also a subspecialist in Genitourinary Pathology and a consultant in Endocrine Pathology, a subspecialty with many homes by organ system. He returned to MGH almost two decades after getting his first taste of research at MGH as a summer student while an undergraduate at Johns Hopkins University. Dr. Sadow's first project (and publication) involved the effects of thyroid hormone on tissue remodeling and wound repair. It was a desire to advance our knowledge of human disease that drove Dr. Sadow to pursue a combined MD/PhD program at the University of Chicago rather than pursuing his other academic passion of Egyptian art and archaeology, having studied Egyptology along with biology as an undergraduate. He has maintained his archaeological interests, even as a pathologist at MGH, and he was in Egypt with a Johns Hopkins excavation team during the Arab Spring in January of 2011.

Dr. Sadow's doctoral thesis at the University of Chicago utilized transgenic mouse models with altered thyroid hormone response genes in order to understand and advance our knowledge of the effects of thyroid hormone on human physiology.

This desire to understand the pathophysiology of endocrine dysfunction led Dr. Sadow to pursue clinical training in Anatomic Pathology at Brigham and Women's Hospital, where he was born, followed by subspecialty training in Endocrine, Genitourinary, and Head & Neck Pathology. 

His clinical and research interests have continued in endocrine pathology, studying the mechanisms of endocrine carcinogenesis through translational studies involving the proteomics and genomics of endocrine neoplasia, primarily of the thyroid & adrenal glands.

In addition to his clinical & research interests, Dr. Sadow has a prominent teaching roles in the hospital, medical school, and in continuing medical education courses.

Clinical Interests:



Mass General Pathology
55 Fruit St.
Boston, MA 02114
Phone: 617-643-0800

Medical Education

  • MD, University of Chicago Pritzker School of Medicine
  • Residency, Brigham and Women's Hospital
  • Fellowship, Brigham and Women's Hospital

American Board Certifications

  • Anatomic Pathology, American Board of Pathology

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Endocrine tumors are challenging for pathologists in that they often appear benign under the microscope. Additionally, high levels of morphologic atypia in endocrine tumors do not equate with malignancy. Often, these diagnoses are highly subjective and may lead to a diversity of opinions. In endocrine pathology, the most straight-forward way to achieve diagnostic concordance is in the setting of tumor metastasis. Even in this circumstance, especially with paragangliomas, multifocal disease may be present and non-malignant. Thus, a challenge to our field is identifying morphologic, genomic and proteomic features that may determine the biological potential of particular tumors.

Genomic studies by The Cancer Genome Atlas identified known and novel genetic anomalies in thyroid and adrenal cancers. These findings are not the silver bullet that we were seeking, but they have certainly allowed us to better classify tumor types, like the reclassification of a particular thyroid tumor, the non-invasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP), as benign. In tumors of the adrenal medulla and paraganglia, we have noted specific genetic anomalies associated with cancer syndromes, such as multiple endocrine neoplasia (MEN), Von Hippel Lindau (VHL), and Familial Paragangliomatosis (FP). These syndromes are associated with known mutations in RET (MEN), VHL (VHL) and SDH (FP) genes.

For as much as we know, we are stymied in our ability to predict how some tumors will behave, as a majority, for sure, have little biological potential, while some will ultimately kill the patient. So, in this, we have a conundrum. It is a classification problem, a treatment problem, and a perfect challenge for those interested in endocrine neoplasia to advance the field diagnostically along with our basic understanding of its pathophysiology.


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