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Mark D Johnson, MD PHD

Neurological Surgery Physician in Worcester, MA · enumerated 2006.

Data current as of Jul 13, 2026 · sourced from CMS NPPES

National Provider Identifier

1578501797

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Registry record

Entity type Individual (Type 1)
Name Mark D Johnson
Credential MD PHD
Sex Male
Practice address 55 Lake Ave N, Worcester, MA, 01655
Phone (508) 856-2963
Enumeration date Jun 2, 2006
Last updated in NPPES Oct 26, 2020

Taxonomy & licenses

207T00000X Neurological Surgery Physician Allopathic & Osteopathic Physicians · License 217384 (MA) Primary

What is an NPI number?

A National Provider Identifier (NPI) is a unique 10-digit number that CMS assigns to every U.S. healthcare provider and organization under HIPAA. Type 1 NPIs identify individual providers; Type 2 NPIs identify organizations. The NPI appears on insurance claims, prescriptions, and credentialing paperwork, and never changes, even if the provider moves or changes specialty.

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Frequently asked questions

Is this the official NPI registry?
No. NPI Portal is a private site built on public CMS NPPES data. The official registry is npiregistry.cms.hhs.gov, operated by CMS.
What specialty is Mark Johnson?
Mark Johnson is registered in NPPES with the primary taxonomy of Neurological Surgery Physician. The taxonomy code describes the provider's classification and area of specialization for claims and credentialing.

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Source: CMS NPPES (public data). Snapshot 2026-07-13. Provider record last updated 2020-10-26.