What was the name of House M.D.'s fictional medical specialty?

Gregory House's fictional medical specialty in House M.D. was diagnostic medicine.

House led the Department of Diagnostic Medicine at Princeton-Plainsboro Teaching Hospital. His team investigated patients whose symptoms did not fit ordinary diagnoses, often combining knowledge from infectious disease, neurology, immunology, oncology, and other specialties.

Diagnostic medicine is a real area of clinical practice, although the show's department and House's unusually broad authority are fictionalized. In real hospitals, diagnostic work is usually shared across specialties, laboratories, imaging services, and multidisciplinary teams rather than concentrated in one small group that handles nearly every mysterious case.

The specialty is often confused with emergency medicine because many episodes begin with urgent symptoms, but the two fields have different roles. Emergency medicine focuses on immediate stabilization and acute care. House's team focused on identifying difficult underlying causes, frequently after other doctors had failed to explain the patient's condition.