Southern Illinois Dermatology Data Breach Impacts 160,312 Individuals

Herrin-headquartered Southern Illinois Dermatology recently disclosed a data breach involving sensitive personal and medical information that has impacted 160,312 individuals across the United States, according to the U.S. Department of Health and Human Services disclosure.

On Nov. 28, 2025, Southern Illinois Dermatology learned that certain systems within its network environment were affected by a cybersecurity incident, according to the company's notification. The company launched an investigation and brought in third-party cybersecurity professionals experienced in handling these types of incidents.

While the investigation was still underway, a threat actor known as Insomnia posted a claim on the dark web on Feb. 7, 2026. The claim, made on the dark web, alleged that the group had leaked sensitive data from Southern Illinois Dermatology.

The types of information exposed included full names, addresses, dates of birth, Social Security numbers, telephone numbers, email addresses, person numbers and medical record numbers. The specific types of data involved varied from person to person.

The breach was disclosed to the Massachusetts Office of Consumer Affairs and Business Regulation on April 2, 2026, with eight Massachusetts residents identified as affected. Southern Illinois Dermatology also posted a notice about the incident on its website on the same date.

Southern Illinois Dermatology's response

Southern Illinois Dermatology sent notification letters to affected individuals that included detailed guidance on how to protect their personal and medical information by placing fraud alerts, requesting credit freezes and monitoring for signs of medical identity theft.

For individuals with questions about the incident, Southern Illinois Dermatology set up a dedicated toll-free response line at 1-833-997-6029. The response line is available Monday through Friday between 8 a.m. and 8 p.m. Eastern Time.