Quest Diagnostics Data Breach Investigation: Edelson Lechtzin LLP Probes Class Action Claims After Unauthorized Access to Patient Records

National class action law firm offers free, confidential case evaluations to Quest Diagnostics patients and others whose information may have been exposed.

SECAUCUS, N.J., Oct. 23, 2026 /PRNewswire/ -- Edelson Lechtzin LLP, a national class action law firm, is investigating data privacy claims arising from a data breach at Quest Diagnostics, a Secaucus, New Jersey-based clinical diagnostic laboratory company and one of the largest lab testing providers in the United States. Anyone who received a breach notice or believes their information may have been exposed can request a free case evaluation.

What Happened

On October 21, 2026, Quest Diagnostics identified unauthorized access to its Quanum Lab Services Manager (LSM) system, a platform certain clients use to place test orders and receive and look up test results. In a Form 8-K filed with the U.S. Securities and Exchange Commission on October 22, 2026, the company disclosed that an unauthorized party accessed certain patient records. Quest notified federal law enforcement, engaged third-party cybersecurity experts, and initiated its incident response procedures.

After detecting the incident, Quest implemented remedial measures and temporarily paused access to the LSM system while it investigates, noting that clients can continue to place orders and receive results through other channels. The company has said the incident has not materially disrupted its business operations or its ability to serve patients. As of its disclosure, no threat group had claimed responsibility, and the company had not stated when the unauthorized access began or whether any ransom demand had been made.

What Information Was Exposed

According to Quest Diagnostics, the information involved may include:

• Patient records, including protected health information
• Health and medical records maintained in the Quanum platform
• Associated diagnostic, test-result, and billing data

Quest said it is still investigating which specific types of data were accessed, and it has not yet determined the full scope of the incident.

Who May Be Affected

The investigation focuses on patients whose personal and health information was maintained in Quest's Quanum LSM system. Quest's materials state that Quanum is used by approximately half a million clinicians in thousands of locations across North America. The company has not yet said how many patients or healthcare customers had information accessed in the incident.

This is not the first major data incident to affect Quest Diagnostics. In 2019, a breach at the company's former billing vendor, American Medical Collections Agency (AMCA), exposed the protected health information of approximately 11.9 million Quest patients. Quest has said the current incident is unlikely to be on a similar scale because only certain clients use the affected system.

Your Legal Options

Edelson Lechtzin LLP is investigating a potential class action on behalf of individuals whose data may have been compromised. A successful case could recover compensation for losses such as lost time, out-of-pocket costs, and loss of privacy, and could press Quest Diagnostics to strengthen its data protection. The firm evaluates claims at no cost.

Recommended Steps to Protect Yourself

• Watch for any notice from Quest Diagnostics and keep any enclosed instructions or enrollment code.
• Place a free fraud alert or credit freeze with Equifax, Experian, and TransUnion, and obtain your free reports at AnnualCreditReport.com.
• Review your bank, card, insurance, and explanation-of-benefits statements for anything you do not recognize, and report suspected identity theft to the Federal Trade Commission at IdentityTheft.gov.

Contact Us for a Free Case Evaluation

Speak confidentially with a data privacy attorney: Marc Edelson, Esq., Edelson Lechtzin LLP, 411 S. State Street, Suite N-300, Newtown, PA 18940; Phone: 844-696-7492; Email: [email protected]; or click HERE to request a free consultation.

About Edelson Lechtzin LLP

Edelson Lechtzin LLP is a national class action law firm with offices in Pennsylvania and California. Beyond data breach litigation, the firm handles class and collective actions involving securities and investment fraud, antitrust violations, ERISA benefit plans, wage theft, and consumer fraud.

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Legal Notice: This press release may be considered Attorney Advertising in some jurisdictions. Prior results do not guarantee a similar outcome.

SOURCE Edelson Lechtzin LLP