Leon Pappas, MD, PHD
Leon Pappas, MD, PHD is a Medical Oncology Physician in Boston, MA, registered under NPI 1164910519. This provider registers 2 separate taxonomy codes, which usually means they practise across more than one recognised specialty.
Getting there
The practice address on file is 55 FRUIT ST, Boston, MA 02114. We have not yet mapped what surrounds this office — parking, transit, and nearby pharmacies are added as our data collection reaches each location.
Credentials and Medicare
| Licence | State | Specialty |
|---|---|---|
| 1016384 | MA | Medical Oncology Physician primary |
| 1016384 | MA | Internal Medicine Physician |
This provider holds licence 1016384 issued in MA. A licence number in NPPES reflects what was filed at registration — it does not confirm the licence is still active today.
- Status
- Approved
- Provider type
- Practitioner - Internal Medicine
- PAC ID
- 5698004919
- Enrollment ID
- I20240606003123
Medicare enrolment is recorded as approved under the provider type Practitioner - Internal Medicine. Being enrolled means the provider can bill Medicare; it does not tell you whether they are currently accepting new Medicare patients. Call the office to confirm.
What Medical Oncology covers
An internist who specializes in the diagnosis and treatment of all types of cancer and other benign and malignant tumors. This specialist decides on and administers therapy for these malignancies as well as consults with surgeons and radiotherapists on other treatments for cancer. NUCC Health Care Provider Taxonomy, code 207RX0202X
All registered taxonomy codes
This provider registers 2 taxonomy codes. The primary code is what appears on most claims; the others record additional recognised specialties.
| Code | Specialty | Licence | State | |
|---|---|---|---|---|
| 207RX0202X | Medical Oncology Physician Medical Oncology | 1016384 | MA | primary |
| 207R00000X | Internal Medicine Physician | 1016384 | MA |
The taxonomy records how the provider classifies their own practice. It does not confirm which conditions they currently treat, whether they are accepting new patients, or which insurance they take — call the office for that.
Full NPPES record
An NPI-1 identifies a single person. It stays with the clinician for life, even if they move practice or change state, which is why the address on file can lag behind where they actually work today.
| NPI | 1164910519 valid check digit |
|---|---|
| Entity type | Individual (NPI-1) |
| Enumeration date | May 1, 2018 |
| Last updated | Feb 10, 2026 |
| Status | Active |
| Sole proprietor | No |
| Credential | MD, PHD |
| Practice address |
55 FRUIT ST Boston, MA 02114 (617) 643-0596 |
Number check
How the check works, step by step
Every NPI carries a Luhn check digit — the same scheme used on credit cards. CMS prefixes the number with 80840 before computing it, which marks it as a US health identifier.
| Digit | 8 | 0 | 8 | 4 | 0 | 1 | 1 | 6 | 4 | 9 | 1 | 0 | 5 | 1 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Doubled? | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 |
| Value | 8 | 0 | 8 | 8 | 0 | 2 | 1 | 3 | 4 | 9 | 1 | 0 | 5 | 2 |
Sum = 51 · next multiple of 10 = 60 · check digit = 9 · actual last digit = 9
A valid check digit only means the number is well-formed. It does not mean the provider is licensed, active, or in good standing — those are separate questions answered by the sections above.