Mountain Rheumatology Data Breach Affects 5,378 Patients

Mountain Rheumatology Professional LLC, a rheumatology medical group based in Denver, Colorado, reported a data breach that affected 5,378 individuals in the United States.

The practice specializes in the diagnosis and treatment of conditions affecting the joints, muscles, bones and tendons.

The breach was disclosed to the U.S. Department of Health and Human Services on Aug. 14, 2026.

The details surrounding the Mountain Rheumatology data breach remain limited based on publicly available information as of Sept. 3, 2026. The timeline of events, the specific types of personal or health information that were exposed and how the breach was first discovered have not been outlined in publicly accessible filings.

However, the HHS Office for Civil Rights breach portal is the federal government's primary system for tracking breaches of unsecured protected health information reported by healthcare providers, health plans and other covered entities under federal health privacy law.

Mountain Rheumatology's filing indicates that the incident involved protected health information.

Mountain Rheumatology's response to the breach

Individuals who have questions about the breach or who believe their personal or health information may have been involved can contact Mountain Rheumatology by phone at 303-861-2190. The practice's office hours are Monday through Thursday from 7:40 a.m. to 5:00 p.m. and Friday from 7:40 a.m. to 4:30 p.m.

Affected individuals should also watch their mail closely for a notification letter from the practice in the coming weeks.

This article will be updated as additional information about the practice's response becomes available.