NPIMap

Individual provider Active NPI

Abner Louissaint Jr., MD, PHD

  • Anatomic Pathology & Clinical Pathology Physician
  • Boston, MA
National Provider Identifier
1124154950
Registry record updated May 15, 2026
On this page

Key facts

NPPES NPI Registry
Primary specialty
Anatomic Pathology & Clinical Pathology PhysicianTaxonomy code 207ZP0102X
License
L-225010 Issued in MA
Practice address
Massachusetts General Hospital
55 Fruit Street
Boston, MA 02114
Phone
(617) 726-2967
NPI assigned
Feb 26, 2007
Sex
Male
Sole proprietor
No

NPPES NPI Registry

Updated by the provider on May 15, 2026

Registry information is reported by the provider to CMS and is not verified. About this source

Specialties & licenses 1

Specialty (taxonomy)CodeLicenseStatePrimary
Anatomic Pathology & Clinical Pathology Physician 207ZP0102X L-225010 MA Primary

Addresses

Primary practice location

Massachusetts General Hospital
55 Fruit Street
Boston, MA 02114

Mailing address

Massachusetts General Hospital
55 Fruit Street
Boston, MA 02114
Phone (617) 726-2967

Other practice location 1

75 Francis St
Boston, MA 02115-6110
Phone (617) 732-5500

Medicare participation

Medicare enrollment files
Medicare fee-for-service enrollment
Enrolled in MA
Eligible to order & refer
  • Part B services
  • Medical equipment
  • Home health
  • Power mobility devices
  • Hospice
Green means eligible to order or refer.

Enrollment records 1

Enrollment IDStateProvider typePAC IDDetails
I20100809000170 MA Practitioner - Pathology 7517090723 Reassigns benefits to 3 organizations

Care Compare profile

Medicare Care Compare
Specialty
Pathology
Education
Other, 2005
Medicare assignment
Accepts the Medicare-approved amount as payment in full
Group practices
Massachusetts General Physicians Organization IncGroup PAC ID 2466365820, 3,494 clinicians

Practice addresses (Care Compare)

243 Charles St
Suite 1107
Boston, MA 02114-3002
Phone (617) 273-5699

55 Fruit St
Boston, MA 02114-2696
Phone (617) 724-0287

75 Francis St
Boston, MA 02115-6110
Phone (617) 732-5500

Hospital & facility affiliations

  • Massachusetts General Hospital Hospital, Boston, MA, CCN 220071
  • Brigham and Women'S Hospital Hospital, Boston, MA, CCN 220110
  • Massachusetts Eye and Ear Infirmary - Hospital, Boston, MA, CCN 220075
  • Cooley Dickinson Hospital Inc,the Hospital, Northampton, MA, CCN 220015

National Provider Directory

National Provider Directory
Medicare enrollment (NPD)
Enrolled
Credentials
Doctor of Medicine, Doctor of Philosophy

State licenses

LicenseStateTypeSpecialty
L-225010MAMDAnatomic Pathology & Clinical Pathology Physician

Practice roles

OrganizationSpecialtyStatusNew patients
General Hospital Corp Current Accepting new patients
Massachusetts General Physicians Organization Inc Anatomic Pathology & Clinical Pathology CurrentSince Jul 1, 2010 Accepting new patients
The General Hospital Corporation CurrentSince Jul 1, 2010 Accepting new patients

Locations

75 Francis St
Boston, MA 02115

55 Fruit St
Boston, MA 02114

55 Fruit St
#2
Boston, MA 02114
Phone (617) 726-2967

Interoperability endpoints

  • Direct secure messaging: louissaint.abner.mgh@direct.partners.masshiway.net

Organizations & group practices 4

Organizations this provider is connected to: Medicare benefit reassignments (the organization bills Medicare for this provider’s services), Care Compare group memberships and National Provider Directory roles.

Hospital & facility affiliations 5

Hospitals and other facilities this clinician is affiliated with according to Medicare Care Compare.

NPI Registry JSON

The complete NPPES record for this NPI in the NPI Registry API format.

{
    "created_epoch": "1172448000000",
    "enumeration_type": "NPI-1",
    "last_updated_epoch": "1778803200000",
    "number": "1124154950",
    "addresses": [
        {
            "country_code": "US",
            "country_name": "United States",
            "address_purpose": "MAILING",
            "address_type": "DOM",
            "address_1": "MASSACHUSETTS GENERAL HOSPITAL",
            "address_2": "55 FRUIT STREET",
            "city": "BOSTON",
            "state": "MA",
            "postal_code": "02114",
            "telephone_number": "617-726-2967"
        },
        {
            "country_code": "US",
            "country_name": "United States",
            "address_purpose": "LOCATION",
            "address_type": "DOM",
            "address_1": "MASSACHUSETTS GENERAL HOSPITAL",
            "address_2": "55 FRUIT STREET",
            "city": "BOSTON",
            "state": "MA",
            "postal_code": "02114",
            "telephone_number": "617-726-2967"
        }
    ],
    "practiceLocations": [
        {
            "address_1": "75 Francis St",
            "address_purpose": "LOCATION",
            "city": "Boston",
            "state": "MA",
            "postal_code": "021156110",
            "country_code": "US",
            "telephone_number": "617-732-5500",
            "country_name": "United States",
            "address_type": "DOM"
        }
    ],
    "basic": {
        "last_name": "LOUISSAINT",
        "first_name": "ABNER",
        "name_suffix": "Jr.",
        "credential": "MD, PHD",
        "sole_proprietor": "NO",
        "sex": "M",
        "enumeration_date": "2007-02-26",
        "last_updated": "2026-05-15",
        "certification_date": "2026-05-15",
        "status": "A"
    },
    "taxonomies": [
        {
            "code": "207ZP0102X",
            "taxonomy_group": "",
            "desc": "Pathology, Anatomic Pathology & Clinical Pathology",
            "state": "MA",
            "license": "L-225010",
            "primary": true
        }
    ],
    "identifiers": [],
    "endpoints": [],
    "other_names": []
}

Other providers in Boston, MA

Sources for this page

Verify at the official NPI Registry.