Breach filing
ArchivedMSK Group: 566,236 individuals, May 2018.
MSK Group reported a breach of unsecured protected health information to the HHS Office for Civil Rights on 22 May 2018. The filing records the organisation as a healthcare provider in Tennessee and lists 566,236 individuals affected, which makes it the 10th largest of the 196 Tennessee filings on the register and the 6th largest of the 369 filings submitted nationally in 2018. Among the 7 Tennessee filings made in 2018 it ranks 1st.
Individuals affected
566,236
As reported to HHS
Modelled cost (IBM 2025)
$90.6M
Upper bound, method shown
Rank in TN
10th
of 196 Tennessee filings
Rank in 2018
6th
of 369 filings nationally
Section F.1 / The filing
As posted by HHS OCR
Every value below is the portal's own field for this filing, plus its rank within the register.
- Covered entity type
- Healthcare Provider
- Individuals affected
- 566,236
- Breach submission date
- 22 May 2018
- Submission year
- 2018
- Type of breach
- Hacking/IT Incident
- Location of breached information
- Network Server
- Business associate present
- No
- State
- Tennessee (TN)
- Portal status
- listed in the HHS OCR breach portal archive
- Rank in Tennessee by size
- 10th of 196
- Rank in 2018 nationally
- 6th of 369
- Tennessee median filing
- 3,371 individuals
- Register id (derived)
- TN-20180522-msk-group
Section F.2 / In context
Where this filing sits in Tennessee and in 2018
OCR classifies the incident as a hacking or IT incident, with the breached information held in a network server. Hacking/IT Incident is the type recorded on 121 of the 196 Tennessee filings (62%) and on 45% of all filings submitted in 2018. Network Server appears on 43% of Tennessee filings.
No business associate is recorded on the filing; 36% of Tennessee filings do involve one. At 566,236 individuals the breach is 168 times the Tennessee median filing of 3,371 and 142 times the national median of 4,000 across all 7,884 filings. It is one of 801 filings of 100,000 or more individuals.
As of 28 August 2026 the case is listed in the HHS OCR breach portal archive. OCR's closing summary of the case is reproduced in full below.
Tennessee's breach notification statute (Tenn. Code Ann. 47-18-2107) requires notice to affected residents immediately, but no later than 45 days from discovery or notification. Its attorney general threshold: no mandatory AG notification for private-sector breaches. The HIPAA Breach Notification Rule ran alongside it: notice to affected individuals and to HHS without unreasonable delay and no later than 60 days after discovery, which is the clock that put this filing on the portal.
Multiplying 566,236 individuals by IBM's $160 customer-PII cost per record (Cost of a Data Breach 2025, the figure the site's calculator uses) gives a modelled $90.6M; the 2026 edition's $192 gives $109M. Both are modelled estimates with the method shown, not costs disclosed by MSK Group. Because the filing is above the roughly 100,000-record range in which the per-record figure is reliable, the result is an upper bound, not an estimate: fixed costs are spread across far more records at this scale.
Section F.3 / OCR closing summary
The portal's archived description, in full
Written by the Office for Civil Rights when the case was closed and reproduced verbatim from the HHS export.
The covered entity (CE), MSK Group PC, discovered on May 7, 2018, that ransomware blocked access to its computer servers which the contained electronic protected health information (ePHI) of 566,236 former and current patients. The ePHI potentially affected included demographic, clinical, and health insurance information. The CE was unable to determine whether ePHI had been copied or transferred outside of the network. The CE timely performed its breach notification obligations. In response to the breach, the CE engaged an information technology firm to continuously monitor its information systems and respond to suspicious activity. The CE also retrained its workforce and implemented substantial technical safeguards, including upgrading firewall protections, reconfiguring servers, and restricting remote access. OCR obtained assurances that the CE implemented the corrective actions listed above and performed its notification obligations.
Section F.5 / Modelled cost
566,236 individuals through IBM's per-record figures
Modelled cost / method shown, not a disclosed cost
Upper boundIBM 2025 customer PII, $160 per record
$90.6M
566,236 x $160
IBM 2026 customer PII, $192 per record
$109M
566,236 x $192
Method: individuals affected, as reported by MSK Group to HHS, multiplied by IBM's customer-PII cost per record (Cost of a Data Breach 2025 Figure 6 and the 2026 edition). No cost has been disclosed by the entity for this filing; the figure is a planning estimate, not a fact about the breach. IBM's per-record figures come from mid-volume breaches and IBM cautions against applying them to breaches involving millions of records; the site's per-record page explains where the multiplication holds and where it breaks down.
Context: IBM's average cost of a healthcare breach is $6.64M in the 2026 report ($7.42M in 2025); the global average across all sectors was $4.44M in 2025.
Cost per record: method and limits / Healthcare breach cost, IBM 2026
Section F.6 / Notification clock
Tennessee statute and the HIPAA rule
State notification statute
Tennessee: Tenn. Code Ann. 47-18-2107
- Notice to individuals
- Immediately, but no later than 45 days from discovery or notification
- Attorney general threshold
- No mandatory AG notification for private-sector breaches
- Private right of action
- Yes: Affected customers may sue to recover damages and obtain injunctive relief
- Penalty
- AG may pursue civil penalties, injunctive relief, and restitution; class actions restricted
The HIPAA Breach Notification Rule runs alongside the state statute: notice to affected individuals and to HHS without unreasonable delay and no later than 60 days after discovery.
Section F.7 / Peer filings
Tennessee filings closest in size
Neighbours by size rank among Tennessee filings in 2018, topped up from other years where 2018 has too few. Filings of 10,000 or more link to their own page.
| Covered entity | Type | Individuals | Submitted | Breach type | Location | BA |
|---|---|---|---|---|---|---|
| United Seating and Mobility, L.L.C., d/b/a Numotion | Healthcare Provider | 688,852 | 1 May 2024 | |||
| Plaza Radiology, LLC | Healthcare Provider | 569,022 | 20 Dec 2023 | |||
| Unum Group SACE | Health Plan | 559,315 | 3 Aug 2023 | |||
| Decatur County General Hospital | Healthcare Provider | 24,000 | 26 Jan 2018 | |||
| Knoxville Heart Group, Inc. | Healthcare Provider | 15,995 | 27 Apr 2018 |
Index / Companion schedules
13 HHS breach register
→Hub: every filing, by state, year and entity.
04 Biggest breaches
→Mega-breaches with primary-source cost figures.
Industry / Healthcare
→IBM 2026: $6.64M average, 13 years at #1.
Regulation / HIPAA penalties
→OCR enforcement tiers and the 60-day rule.
11 50-state laws
→Deadline, AG threshold and penalties per state.
Cost / Per record
→Where the per-record model is reliable.
Provenance
Source: U.S. Department of Health and Human Services, Office for Civil Rights, Breach Portal (breaches affecting 500 or more individuals), retrieved 2026-08-28. Public domain. Individuals affected and dates as reported by the covered entity.
Portal: ocrportal.hhs.gov breach report. Statutory basis: HITECH Act section 13402(e)(4): the Secretary must post a list of breaches of unsecured protected health information affecting 500 or more individuals. Breaches affecting fewer than 500 individuals are reported to OCR annually and are not posted, so they are not on this register. Status wording follows the portal's two tabs ("Cases Currently Under Investigation" and "Archive") as of 28 August 2026; a filing moves to the archive when OCR closes the case. Modelled costs on this site are a method applied to the reported count, using IBM Cost of a Data Breach per-record figures, and are never a cost disclosed by the entity. This row: hhs-breach-archive__2026-08-28.csv, export row 4851.
Corrections: if you represent a listed entity and the portal row has been amended, email [email protected] with the portal entry and we will re-pull the export.