🦷 CPT Code 21045 — Excision of Malignant Tumor of Mandible; Requiring Bone Graft (Includes Obtaining Graft)

Quick Reference

Global Period: 090 days | wRVU: 22.93 | Assistant Payable: ✅ Yes | Co-Surgeon: ✅ Yes | Category: Musculoskeletal – Head | Bone Graft Harvest: ✅ Included

📋 Official CPT Description

CPT 21045 — Excision of malignant tumor of mandible; requiring bone graft (includes obtaining graft)

This code describes the surgical resection of a malignant neoplasm of the mandible (lower jaw) at a level of complexity requiring bone graft reconstruction as part of the same operative session. The code explicitly includes the harvesting of the bone graft — meaning the graft procurement itself (e.g., from iliac crest, rib, calvarium, or fibula) is not separately billable when performed to reconstruct the mandibular defect created during tumor excision. This is a high-complexity craniofacial oncologic procedure requiring advanced surgical training in oral-maxillofacial, head and neck, or reconstructive surgery.

🧠 Detailed Clinical Description

Anatomical Context — The Mandible

The mandible (lower jaw) is a U-shaped bone forming the inferior portion of the facial skeleton. It is the only mobile bone of the skull and articulates bilaterally with the temporal bones at the temporomandibular joints (TMJ). Key anatomical zones relevant to surgical planning include:

Region	Description
Symphysis	Midline anterior segment; chin region
Parasymphysis	Lateral to midline, anterior to mental foramen
Body	Horizontal segment bearing posterior dentition
Angle	Junction of body and ramus, posterior
Ramus	Vertical posterior segment
Condyle	Superior articular process at TMJ
Coronoid Process	Anterior superior ramus; temporalis attachment
Alveolar Process	Tooth-bearing superior ridge

Malignant tumors of the mandible may arise primarily from the bone itself (e.g., osteosarcoma, Ewing sarcoma, chondrosarcoma) or represent direct invasion from adjacent oral cavity squamous cell carcinoma (SCC) — the most common mechanism, particularly from floor of mouth, lower gingiva, or buccal mucosa primaries.

What 21045 Describes Clinically

21045 is performed when:

A malignant tumor involves the mandible — either primary bone malignancy or SCC invading cortical/medullary bone
The extent of resection creates a bony defect requiring grafting for structural continuity, occlusal function restoration, or preparation for future implant-based or prosthetic rehabilitation
The bone graft is harvested from the patient (autologous) — most commonly iliac crest, rib, calvarium, or fibula cortex

The resection may range from a marginal mandibulectomy (preserving inferior border continuity) requiring graft for focal cortical defect, to a segmental mandibulectomy (through-and-through resection interrupting mandibular continuity) with immediate bone graft bridging.

Marginal vs. Segmental Mandibulectomy

Marginal (rim) mandibulectomy — Removes a portion of the alveolar process or cortical bone but preserves inferior border continuity. Used when tumor involves cortex superficially without deep medullary invasion.

Segmental mandibulectomy — Full-thickness removal of a mandibular segment, interrupting bony continuity. Creates a “jaw gap” requiring immediate reconstruction with graft or free flap (e.g., fibula free flap — coded separately as 15756 if myocutaneous).

Both may fall under 21045 when bone graft is required, but the complexity of segmental resection with through-and-through reconstruction often warrants modifier 22 with supporting documentation.

Bone Graft Harvest — Included in 21045

The following graft harvest procedures are included (not separately billable) per CPT parenthetical instruction:

Graft Source	Notes
Iliac crest (anterior or posterior)	Most common; cortical, cancellous, or corticocancellous
Rib graft	Cortical strut or costochondral segment
Calvarium (split calvarial)	Outer table harvest; low donor morbidity
Tibial plateau / proximal tibia	Cancellous graft source
Local mandibular graft	Rarely sufficient for malignant resection defects

Fibula Free Flap Exception

When reconstruction requires a vascularized fibula free flap (the gold standard for segmental mandibular reconstruction), the operative complexity and technique differ substantially from a non-vascularized bone graft. A fibula osteocutaneous free flap with microvascular anastomosis is coded as 15756 (if including skin/muscle) or a composite free flap — not as a bone graft under 21045. In these cases, 21045 may still be reported for the mandibular resection itself, with the free flap coded separately. Verify NCCI edits and document distinct procedures clearly.

Surgical Steps Included in 21045

Preoperative imaging review — CT, MRI, PET-CT for tumor mapping, bone invasion depth, and surgical margin planning (not separately billable as part of global)
Patient positioning and airway management — Often nasotracheal intubation; tracheotomy may be separately coded (31600) if planned
Incision and exposure — Intraoral and/or extraoral (transcervical) approach depending on tumor location and extent
Periosteal elevation and tumor identification — Mapping of surgical margins with frozen section guidance
Osteotomy — Planned bone cuts with oscillating or reciprocating saw; margins confirmed intraoperatively
En bloc resection — Removal of involved mandibular segment with adequate bony and soft tissue margins
Frozen section margin analysis — Integrated into operative workflow; not separately coded
Bone graft harvest — Procurement of autologous graft from secondary donor site (bundled per CPT parenthetical)
Graft shaping and fixation — Contouring graft to defect; fixation with plates, screws, or wires
Closure — Layered intraoral mucosal closure ± external skin closure
Drain placement — Jackson-Pratt or similar; not separately billable within global

💰 Reimbursement & RVU Profile

Component	Value
Work RVU (wRVU)	22.93 ^{CMS MPFS 2025}
Global Period	090 days
Assistant Surgeon Payable	✅ Yes (Indicator: 1)
Co-Surgeon Payable	✅ Yes
Team Surgery	✅ Yes
Facility Only	Yes (hospital/ASC setting)
Multiple Procedure Indicator	2 (standard reduction applies)
Bilateral Surgery Indicator	0 (not applicable)

wRVU in Context

At 22.93 wRVU, 21045 reflects the substantial intraoperative complexity of malignant mandibular resection with graft reconstruction. For comparison:

Code wRVU Procedure
21044 ~14.00 Malignant mandible tumor excision, no graft
21045 22.93 Malignant mandible excision + bone graft
21040 ~3.97 Benign mandible tumor excision, no graft
21046 ~8.17 Benign mandible tumor, intraoral osteotomy
21047 ~12.43 Benign mandible tumor, extra-oral osteotomy

Code	wRVU	Procedure
21044	~14.00	Malignant mandible tumor excision, no graft
21045	22.93	Malignant mandible excision + bone graft
21040	~3.97	Benign mandible tumor excision, no graft
21046	~8.17	Benign mandible tumor, intraoral osteotomy
21047	~12.43	Benign mandible tumor, extra-oral osteotomy

✅ Included Services (Bundled into 21045)

The following are not separately reportable when performed as integral components of 21045:

En bloc resection of malignant mandibular tumor
All osteotomies required to complete the resection
Intraoperative frozen section margin sampling (as part of procedure flow)
Autologous bone graft harvest from any donor site (per CPT parenthetical)
Graft contouring and shaping
Rigid fixation (plates and screws) for graft stabilization
Simple or intermediate wound closure at operative site
Drain placement at operative site
Routine postoperative management within 90-day global period
Routine dressing changes and suture/staple removal within global

❌ Excludes / Separately Reportable Services

The following may be billed separately when clearly documented as distinct services:

Separate Service	Code
Planned tracheotomy for airway management	31600
Neck dissection (selective or radical)	38700, 38720, 38724
Partial glossectomy for floor of mouth / tongue involvement	41120, 41130, 41135
Free flap reconstruction (fibula, ALT, radial forearm, etc.)	15756, 15757, 15758
Skin graft for intraoral or external coverage	15100–15115
Alloplastic implant reconstruction (if autologous graft not used)	21248, 21249
Temporomandibular joint (TMJ) reconstruction	21240, 21242
Return to OR for related complication in global period	21045 with modifier 78
Nerve repair (inferior alveolar / lingual nerve)	64831–64836
Secondary bone graft in staged procedure	20900, 20902
Dental implant placement (staged, separate encounter)	D6010 (dental code)
Postoperative radiation planning	Separately coded by radiation oncology

NCCI Bundling — Neck Dissection

Neck dissection (38720, 38724) is commonly performed in the same operative session as 21045 for oncologic staging and locoregional control. These are separately reportable — they are not bundled with 21045 per NCCI. Append modifier -51 to the lesser-valued procedure and document each procedure distinctly in the operative report. This is one of the highest-yield additional code pairings for head and neck oncology cases.

Bone Graft Harvest — Do Not Double-Bill

CPT 20900 (bone graft, any donor area; minor or small) and 20902 (bone graft, any donor area; major or large) are explicitly included in 21045 per CPT parenthetical instructions. Billing 20900 or 20902 in addition to 21045 in the same session constitutes a NCCI violation unless the graft is harvested for a separate, unrelated recipient site in the same operative session — a rare and carefully documented scenario.

🦴 Mandibular Resection Classification & Code Selection

Surgical Approach to Code Selection — Mandible Tumor Codes

CPT Code	Procedure	Malignant/Benign	Bone Graft?
21040	Excision of benign tumor/cyst of mandible; not requiring bone graft or tooth extraction	Benign	❌
21041	Excision of benign tumor/cyst of mandible; requiring tooth extraction	Benign	❌
21044	Excision of malignant tumor of mandible; without bone graft	Malignant	❌
21045	Excision of malignant tumor of mandible; requiring bone graft	Malignant	✅ Included
21046	Excision of benign tumor/cyst of mandible; requiring intraoral osteotomy	Benign	❌
21047	Excision of benign tumor/cyst of mandible; requiring extra-oral osteotomy	Benign	❌
21048	Excision of benign tumor/cyst of maxilla; without bone graft or tooth extraction	Benign – Maxilla	❌
21049	Excision of malignant tumor of maxilla; without bone graft	Malignant – Maxilla	❌

Mandible vs. Maxilla

CPT 21045 is mandible-specific. Malignant maxillary tumors requiring bone graft are not currently captured by an exact CPT equivalent in the same code family — maxillary resection codes (21032, 21034, 21049) should be used as appropriate, with graft separately evaluated per NCCI. Verify annually as CPT guidelines evolve.

🏷️ Applicable Modifiers

Modifier	Description	When to Use
-51	Multiple procedures	When 21045 is performed alongside neck dissection, glossectomy, free flap, or other major procedure in the same session
-59	Distinct procedural service	To clarify a separately identifiable service not typically billed together; use to unbundle distinct anatomical site procedures
-80	Assistant surgeon	Second surgeon assisting; common in complex jaw resection/reconstruction — payable
-82	Assistant surgeon (no qualified resident)	Teaching hospital alternative when no resident available
-AS	Assistant at surgery – NP/PA	Non-physician practitioner assisting at table
-22	Increased procedural complexity	Prior radiation to jaw (osteoradionecrosis context), extensive tumor, highly complex reconstruction, exceptionally prolonged OR time; requires detailed operative documentation and cover letter
-52	Reduced services	Partial procedure; rarely applicable in oncologic resection
-58	Staged or related procedure by same surgeon	When 21045 is the planned second stage of a staged resection/reconstruction within global period
-78	Return to OR for related procedure during global period	Re-exploration for hardware failure, wound dehiscence, graft failure, or hemorrhage
-79	Unrelated procedure during global period	Separate, unrelated surgery within 90-day global
-LT / -RT	Left / Right laterality	When tumor and resection are lateralized (e.g., right ramus, left body); used per payer requirements

🩺 ICD-10-CM Diagnoses Commonly Paired with 21045

Primary Malignant Tumors of the Mandible & Jaw Bone

ICD-10-CM	Description	HCC?
C41.1	Malignant neoplasm of lower jaw bone (mandible)	✅ HCC 11
C41.0	Malignant neoplasm of bones of skull and face	✅ HCC 11
C41.9	Malignant neoplasm of bone and articular cartilage, unspecified	✅ HCC 11

CPT C41.1 — The Primary Code for Mandibular Malignancy

C41.1 is the go-to code for malignant neoplasm arising from or directly involving the mandibular bone itself. This includes primary bone malignancies (osteosarcoma, chondrosarcoma, Ewing sarcoma, ameloblastic carcinoma with bone invasion) as well as secondary invasion of mandibular bone by an adjacent oral cavity SCC. Carries HCC 11 — direct malignancy category.

Oral Cavity Squamous Cell Carcinoma (Bone Invasion Scenarios)

ICD-10-CM	Description	HCC?
C03.1	Malignant neoplasm of lower gum (mandibular alveolar ridge)	✅ HCC 11
C03.9	Malignant neoplasm of gum, unspecified	✅ HCC 11
C04.0	Malignant neoplasm of anterior floor of mouth	✅ HCC 11
C04.1	Malignant neoplasm of lateral floor of mouth	✅ HCC 11
C04.8	Malignant neoplasm of overlapping sites of floor of mouth	✅ HCC 11
C04.9	Malignant neoplasm of floor of mouth, unspecified	✅ HCC 11
C06.0	Malignant neoplasm of cheek mucosa	✅ HCC 11
C06.2	Malignant neoplasm of retromolar area	✅ HCC 11
C06.9	Malignant neoplasm of mouth, unspecified	✅ HCC 11

SCC with Bone Invasion — Coding Logic

When oral cavity SCC (e.g., floor of mouth C04.9) invades the mandibular cortex, the primary site (oral cavity) drives the principal diagnosis — not C41.1. However, C41.1 may be assigned as an additional diagnosis to capture the bone involvement, supporting medical necessity for mandibular resection and bone graft. Always sequence the primary tumor first per ICD-10-CM neoplasm guidelines.

Odontogenic and Jaw-Specific Malignancies

ICD-10-CM	Description	HCC?
C41.1	Malignant neoplasm of lower jaw bone	✅ HCC 11
C31.0	Malignant neoplasm of maxillary sinus (if maxilla involved secondarily)	✅ HCC 11
C49.0	Malignant neoplasm of connective and soft tissue of head, face, neck	✅ HCC 11

Specific Histologic Types (Use with Morphology/Behavior Context)

ICD-10-CM	Description	HCC?
C41.1 + histology note	Osteosarcoma of mandible	✅ HCC 11
C41.1 + histology note	Chondrosarcoma of mandible	✅ HCC 11
C41.1 + histology note	Ameloblastic carcinoma / malignant ameloblastoma	✅ HCC 11
C41.1 + histology note	Ewing sarcoma of mandible	✅ HCC 11
C41.1 + histology note	Squamous cell carcinoma of mandible (intraosseous)	✅ HCC 11

Histology in ICD-10-CM

ICD-10-CM does not capture histologic tumor type in the diagnosis code itself (unlike ICD-O morphology coding). The histology is reflected in the pathology report and documented in the medical record. For hospital/inpatient coding, the ICD-10-PCS root operation and approach are histology-neutral. For registry and oncology-specific documentation, tumor histology is captured separately via cancer registry (CTR) coding standards.

Osteoradionecrosis (ORN) — Major Comorbidity

ICD-10-CM	Description	HCC?
M87.18	Osteonecrosis due to drugs, other bone	❌
M87.08	Idiopathic aseptic necrosis of bone, other	❌
M27.2	Inflammatory conditions of jaws (osteomyelitis of jaw)	❌
M27.49	Other inflammatory conditions of jaw	❌
K10.2	Inflammatory conditions of jaws	❌

Osteoradionecrosis & 21045

Osteoradionecrosis (ORN) of the mandible — necrotic bone resulting from prior radiation therapy — is a distinct clinical entity from malignant tumor. When 21045 is performed for ORN, it may be miscoded; the correct code selection depends on whether a malignant tumor is being resected (use 21045) or whether the indication is ORN alone (use 21044 or a wound debridement/sequestrectomy code). If residual or recurrent malignancy drives the ORN resection, 21045 remains appropriate with bone graft. Document the indication explicitly. ORN itself maps to:

M87.18 — Osteonecrosis due to drugs (if bisphosphonate-related — MRONJ)

M27.49 — Other inflammatory conditions of jaw (radiation-induced ORN, general mapping)

T66.XXXA — Radiation effects (as additional code)

Complicating Diagnoses & Comorbidities

ICD-10-CM	Description	HCC?
E11.9	Type 2 diabetes mellitus without complications	✅ HCC 19
E11.649	Type 2 diabetes with hypoglycemia without coma	✅ HCC 18
Z79.01	Long-term use of anticoagulants	❌
Z87.891	Personal history of nicotine dependence	❌
F17.210	Nicotine dependence, cigarettes, uncomplicated	❌
E44.0	Moderate protein-calorie malnutrition	✅ HCC 21
E43	Unspecified severe protein-calorie malnutrition	✅ HCC 21
Z96.5	Presence of tooth-root and mandibular implants	❌
Z98.890	Other specified postprocedural states	❌

Malnutrition — MCC-Level Capture

Patients undergoing mandibular malignancy resection — especially post-radiation or with floor of mouth tumors — frequently present with protein-calorie malnutrition from dysphagia and poor oral intake. E43 (severe malnutrition) is an MCC-level diagnosis that significantly elevates DRG weight. Review dietary/nutrition consult notes, albumin/prealbumin levels, and the dietitian’s documented assessment. If the physician has documented and treated malnutrition, code it — it is clinically relevant AND a meaningful reimbursement driver.

Staging / Encounter-Specific Codes

ICD-10-CM	Description	HCC?
Z51.11	Encounter for antineoplastic chemotherapy	❌
Z51.0	Encounter for antineoplastic radiation therapy	❌
Z85.819	Personal history of malignant neoplasm of unspecified site	❌
Z42.8	Encounter for other plastic/reconstructive surgery following healed injury or procedure	❌
Z96.641	Presence of right artificial hip joint (if iliac crest harvest w/ prior hip hardware)	❌

🏨 MS-DRG Mapping

Inpatient Context

In the inpatient acute care hospital setting, procedures are coded using ICD-10-PCS (not CPT). The corresponding ICD-10-PCS root operations for 21045 drive MS-DRG assignment. The principal diagnosis and CC/MCC burden determine the final DRG tier.

Head & Neck Oncologic Procedures

MS-DRG	Description	Approx. Relative Weight
168	Major Head & Neck Procedures w/ MCC	~3.8–4.2
169	Major Head & Neck Procedures w/ CC	~2.5–2.9
170	Major Head & Neck Procedures w/o CC/MCC	~1.8–2.1

DRG 168 — The Target DRG for Complex Mandibulectomy

The vast majority of 21045-type cases, when coded accurately in ICD-10-PCS for the inpatient setting, fall into MS-DRG 168 when MCC-level diagnoses are supported. Given the typical patient population — active malignancy (C41.1, HCC 11), malnutrition (E43, MCC), possible airway complications, and extended LOS — thorough comorbidity capture almost always pushes cases to DRG 168. The difference between DRG 168 and DRG 170 can represent $8, 000-$ 15,000+ in relative weight at most hospital payment rates.

Musculoskeletal — Head/Facial Bone Procedures

MS-DRG	Description	Approx. Relative Weight
039	Extracranial Procedures w/ MCC	~3.2–3.8
040	Extracranial Procedures w/ CC	~2.0–2.4
041	Extracranial Procedures w/o CC/MCC	~1.4–1.8

Oral & Dental Procedures (when principal diagnosis is odontogenic)

MS-DRG	Description	Approx. Relative Weight
185	Dental & Oral Diseases w/ MCC	~1.8–2.1
186	Dental & Oral Diseases w/ CC	~1.1–1.4
187	Dental & Oral Diseases w/o CC/MCC	~0.8–1.0

DRG Optimization — Physician Query Opportunities

For 21045 inpatient cases, high-yield query opportunities include:

Malnutrition — Albumin < 3.0, weight loss > 10%, dietitian documentation → query for E43 (MCC) or E44.0 (CC)

Acute blood loss anemia — Expected with jaw resection; if transfusion given, query for D62 (CC)

Wound complications — Dehiscence, fistula, hardware infection documented in notes → T84.xxx (CC/MCC)

Respiratory failure — Post-tracheotomy or airway edema → J96.xx (MCC)

Sepsis — Post-op infectious complications in irradiated field → A41.9 (MCC)

🌳 CPT Code Tree — Mandible Tumor Excision Family

Mandible Tumor Excision Codes
├── Benign Tumors / Cysts
│     ├── 21040 — Benign tumor/cyst of mandible; no bone graft, no tooth extraction
│     ├── 21041 — Benign tumor/cyst of mandible; requiring tooth extraction
│     ├── 21046 — Benign tumor/cyst of mandible; intraoral osteotomy (local resection)
│     └── 21047 — Benign tumor/cyst of mandible; extra-oral osteotomy
│
├── Malignant Tumors — MANDIBLE
│     ├── 21044 — Malignant tumor of mandible; WITHOUT bone graft
│     └── 21045 ← MALIGNANT TUMOR OF MANDIBLE + BONE GRAFT (THIS CODE)
│
└── Malignant Tumors — MAXILLA
      ├── 21048 — Benign tumor/cyst of maxilla; without bone graft/tooth extraction
      └── 21049 — Malignant tumor of maxilla; without bone graft

Mandibular Reconstruction (Implant-Based):
├── 21248 — Reconstruction of mandible or maxilla, endosteal implant (partial)
└── 21249 — Reconstruction of mandible or maxilla, endosteal implant (complete)

Bone Graft Codes (NOT separately billable with [[21045]]):
├── 20900 — Bone graft, any donor area; minor or small
└── 20902 — Bone graft, any donor area; major or large

Frequently Paired — Neck Dissection:
├── 38700 — Suprahyoid neck dissection
├── 38720 — Cervical lymphadenectomy (radical neck dissection)
└── 38724 — Cervical lymphadenectomy (modified radical neck dissection)

Frequently Paired — Oral Cavity Resection:
├── 41120 — Glossectomy; less than one-half tongue
├── 41130 — Hemiglosectomy
├── 41135 — Partial glossectomy with unilateral radical neck dissection
└── 41140 — Glossectomy, complete or total, without radical neck dissection

Airway Management:
└── 31600 — Tracheotomy; planned (separate code if performed)

Free Flap Reconstruction (when vascularized bone/tissue used):
├── 15756 — Free muscle/myocutaneous flap (e.g., fibula with skin paddle + muscle)
├── 15757 — Free skin/fasciocutaneous flap (e.g., RFFF, ALT)
└── 15758 — Free fascial flap

🗂️ ICD-10-PCS Context (Inpatient Coding)

Inpatient Coder Note (CIC Relevance)

In the inpatient acute care setting, 21045 is not assigned. All procedures are coded in ICD-10-PCS. Mandibular malignant tumor resection with bone graft involves multiple distinct PCS codes covering the resection, reconstruction, and fixation components.

ICD-10-PCS Root Operations for 21045-Type Procedures

Step 1 — Mandibular Resection:

Axis	Value
Section	0 – Medical & Surgical
Body System	N – Head and Facial Bones
Root Operation	B – Excision (partial resection) or T – Resection (complete removal of a body part)
Body Part	B – Mandible, Right / C – Mandible, Left
Approach	0 – Open
Device	Z – No Device
Qualifier	X – Diagnostic (if margins) / Z – No Qualifier

Excision (B) vs. Resection (T) in PCS

Use root operation Excision (B) when a portion of the mandible is removed (marginal or partial segmental resection)

Use root operation Resection (T) when the entire mandible or a named, complete body part unit is removed

Segmental mandibulectomy interrupting continuity but not removing the entire mandible is typically Excision

Step 2 — Bone Graft Harvest (Donor Site):

Axis	Value
Section	0 – Medical & Surgical
Body System	Q – Lower Bones (iliac crest) or P – Upper Bones (rib)
Root Operation	B – Excision
Body Part	Specific donor site (e.g., 2 – Pelvic Bone, Right for iliac crest)
Approach	0 – Open
Device	Z – No Device
Qualifier	Z – No Qualifier

Step 3 — Mandibular Reconstruction with Autologous Bone Graft:

Axis	Value
Section	0 – Medical & Surgical
Body System	N – Head and Facial Bones
Root Operation	R – Replacement (substituting graft for resected bone)
Body Part	B – Mandible, Right / C – Mandible, Left
Approach	0 – Open
Device	7 – Autologous Tissue Substitute
Qualifier	Z – No Qualifier

Step 4 — Internal Fixation (if plates/screws applied):

Axis	Value
Root Operation	H – Insertion
Body Part	Mandible (as appropriate)
Device	4 – Internal Fixation Device

Full PCS Code Set for a Complete Case

A complete 21045-equivalent inpatient case commonly generates 3–4 ICD-10-PCS codes:

Excision of mandible (resection of malignant tumor)

Excision of iliac crest / rib (donor site harvest)

Replacement of mandible with autologous tissue substitute (bone graft inset)

Insertion of internal fixation device (plates/screws)

If neck dissection is performed simultaneously, add the appropriate lymphatic excision PCS code. If a free flap is used, add the Replacement code for soft tissue. Multi-code PCS assignment is expected and appropriate — do not under-code.

📝 Coding Examples

Example 1 — Floor of Mouth SCC with Mandibular Invasion (Otolaryngology / Head & Neck)

Clinical Scenario: Patient with T4a squamous cell carcinoma of the left floor of mouth with radiographic cortical invasion of the left mandibular body. Undergoes composite resection — segmental left mandibulectomy (body segment, 4 cm), floor of mouth excision, and left modified radical neck dissection (levels I–IV). Reconstruction with anterior iliac crest corticocancellous graft fixed with a titanium reconstruction plate.

CPT Codes:

21045 — Excision of malignant tumor of mandible with bone graft (iliac crest harvest included)
41135 — Partial glossectomy with unilateral radical neck dissection (modifier 51)
(Separate operative report documentation for each procedure required)

ICD-10-CM:

C04.1 — Malignant neoplasm of lateral floor of mouth, left (principal) (HCC 11)
C41.1 — Malignant neoplasm of lower jaw bone (mandible) — bone invasion (additional)
F17.210 — Nicotine dependence, cigarettes, uncomplicated (if applicable)

Example 2 — Osteosarcoma of Mandible (Oral Maxillofacial Surgery)

Clinical Scenario: 28-year-old patient with high-grade osteosarcoma of the right mandibular body and ramus confirmed on biopsy. Neoadjuvant chemotherapy completed. Patient undergoes right hemimandibulectomy (condyle-to-midline) with immediate reconstruction using a split rib graft shaped to restore mandibular contour and fixed with a prefabricated titanium plate.

CPT Codes:

21045 — Excision of malignant tumor of mandible; requiring bone graft (rib graft harvest included)
31600 — Planned tracheotomy for airway management (if performed — modifier -51)

ICD-10-CM:

C41.1 — Malignant neoplasm of lower jaw bone (mandible) (principal) (HCC 11)
Z51.11 — Encounter for antineoplastic chemotherapy (if chemo given during same admission)
E44.0 — Moderate protein-calorie malnutrition (if documented — CC)

Example 3 — Ameloblastic Carcinoma with Graft Reconstruction

Clinical Scenario: Patient with biopsy-confirmed ameloblastic carcinoma (malignant ameloblastoma) of the left posterior mandible. Wide resection performed via transcervical approach — segmental left mandibulectomy from angle to body. Reconstruction with anterior iliac crest graft; soft tissue closure with local advancement flap. No neck dissection performed (clinically N0, no suspicious nodes on imaging).

CPT Codes:

21045 — Excision of malignant mandibular tumor with bone graft (iliac crest included)

ICD-10-CM:

C41.1 — Malignant neoplasm of lower jaw bone (principal) (HCC 11)
Z79.01 — Long-term use of anticoagulants (if applicable)

Example 4 — Mandibular Resection with Free Fibula Flap (Complex Reconstruction)

Clinical Scenario: Patient with T4 lower gingival SCC with extensive mandibular body and symphysis invasion. Resection team performs composite segmental mandibulectomy (anterior arch, symphysis to bilateral body, 8 cm segment). Reconstruction team simultaneously performs free fibula osteocutaneous flap harvest with microvascular anastomosis to facial vessels — fibula contoured for mandibular arch reconstruction, skin paddle used for floor of mouth resurfacing.

CPT Codes:

21045 — Excision of malignant mandibular tumor (note: fibula free flap is the primary reconstruction; some payers accept 21045 for the resection component with 15756 for the free flap)
15756 — Free fibula osteomyocutaneous flap with microvascular anastomosis (modifier 51)
38720 — Radical neck dissection (modifier 51)

ICD-10-CM:

C03.1 — Malignant neoplasm of lower gum (principal) (HCC 11)
C41.1 — Malignant neoplasm of lower jaw bone (additional — bone invasion)
E43 — Unspecified severe protein-calorie malnutrition (if documented — MCC)

21045 + Free Flap Coding — Payer Variation

When a free fibula osteocutaneous flap is used for mandibular reconstruction, some payers bundle 21045 into 15756 (viewing the free flap as inclusive of the resection preparation). Others accept both. Review payer-specific NCCI edits and LCDs. Append modifier -59 to 21045 when submitting both codes and provide operative documentation demonstrating two distinct procedures (resection vs. free flap harvest/inset).

Example 5 — Return to OR During Global Period (Hardware Failure)

Clinical Scenario: POD #18 following 21045 with titanium plate fixation. Patient returns to OR for plate exposure and wound dehiscence at intraoral closure site. Plate removed, wound irrigated and primarily re-closed.

CPT Codes:

21045 with modifier 78 — Return to OR for related procedure during postoperative period

ICD-10-CM:

T84.198A — Other mechanical complication of other bone devices, initial encounter
K08.89 — Other specified disorders of teeth and supporting structures (wound dehiscence context)
Underlying principal diagnosis from original surgery (e.g., C41.1)

Example 6 — Staged Reconstruction (Bone Graft, Second Stage)

Clinical Scenario: Patient originally underwent 21044 (mandibular resection without graft) 3 months ago. Now returns for planned secondary iliac crest bone graft to restore mandibular continuity — within the global period of the original surgery but planned as a staged procedure.

CPT Codes:

20902 — Bone graft, major (if staged, separate encounter — now separately billable as distinct session from original 21044)
Or: 21045 with modifier -58 if the operative approach includes additional mandibular work at the recipient site in addition to graft placement

Staged Procedure Logic

When 21045 itself is the original procedure, any planned secondary procedure within the 90-day global is reported with modifier -58 (staged or related by same surgeon). The secondary procedure is not subject to global period payment reduction when -58 is appended — it resets a new global period.

⚠️ Common Coding Pitfalls

21044 vs. 21045 selection — The single most important distinction: Was a bone graft performed? Read the operative report for graft harvest documentation. If no graft, use 21044. If graft performed, 21045 is correct. Upcoding without graft documentation is a compliance risk; undercoding when a graft was performed loses significant wRVU (nearly 9 wRVU difference).
Do not separately bill bone graft harvest (20900, 20902) with 21045 — this is explicitly bundled per CPT parenthetical and NCCI. This is a known audit target.
Free fibula flap vs. bone graft — A vascularized fibula free flap is not a “bone graft” under 21045’s definition. These are different procedures; the fibula flap codes (15756) describe the free flap while 21045 captures the resection. Do not assume 21045 covers the free flap harvest and anastomosis — they are separately reportable.
Benign vs. malignant — 21045 is malignant only. For benign mandibular tumors (ameloblastoma when benign, odontogenic cysts, giant cell granuloma), use 21046 or 21047 as appropriate. Assigning 21045 for a benign tumor is a misrepresentation regardless of operative complexity.
ORN misidentification — Osteoradionecrosis resection and bone grafting is not automatically 21045 — the indication must be malignant tumor resection. ORN debridement alone uses different codes. If malignancy is the indication that caused the ORN and drives the resection, 21045 may apply with proper documentation.
Inpatient setting — CPT is not used in acute inpatient coding. Assign ICD-10-PCS. Expect 3–4 PCS codes for a complete 21045-equivalent procedure. Under-coding to a single PCS code is a common error in complex jaw reconstruction cases.
Neck dissection is always separately reportable — Never assume 21045 includes the neck dissection. Document and bill (38720, 38724) separately with modifier -51.
Modifier -22 discipline — Prior radiation to the mandible is the most common justification; however, the operative note must specifically describe the additional difficulty encountered. A routine mention of radiation history is insufficient. Expect payer requests for documentation.

📚 Brief Source References

^{AMA CPT Professional Edition 2025, codes 21040–21049 and musculoskeletal surgery guidelines} ^{CMS Medicare Physician Fee Schedule Final Rule 2025 – Work RVU and payment indicator files (www.cms.gov/Medicare/Medicare-Fee-for-Service-Payment/PhysicianFeeSched)} ^{CMS NCCI Policy Manual for Medicare Services, Chapter 9: Surgery – Musculoskeletal System, 2025} ^{CMS MS-DRG Definitions Manual v41 FY2024 – Major Head & Neck Procedures DRGs 168–170} ^{ICD-10-PCS Official Guidelines for Coding and Reporting FY2025, Section B3 – Root Operations (Excision, Resection, Replacement)} ^{ICD-10-CM Official Guidelines for Coding and Reporting FY2025, Section I.C.2 – Neoplasms and sequencing guidelines} ^{AAPC CPC/CIC Study Guide – Musculoskeletal Surgery: Head chapter} ^{Shah JP, Patel SG, Singh B. Jatin Shah’s Head and Neck Surgery and Oncology, 4th ed. Elsevier 2012 – Mandibular Resection chapter} ^{Urken ML. Multidisciplinary Head & Neck Reconstruction: A Defect-Oriented Approach. Lippincott Williams & Wilkins 2010}

Explorer

21045

🦷 CPT Code 21045 — Excision of Malignant Tumor of Mandible; Requiring Bone Graft (Includes Obtaining Graft)

📋 Official CPT Description

🧠 Detailed Clinical Description

Anatomical Context — The Mandible

What 21045 Describes Clinically

Bone Graft Harvest — Included in 21045

Surgical Steps Included in 21045

💰 Reimbursement & RVU Profile

✅ Included Services (Bundled into 21045)

❌ Excludes / Separately Reportable Services

🦴 Mandibular Resection Classification & Code Selection

🏷️ Applicable Modifiers

🩺 ICD-10-CM Diagnoses Commonly Paired with 21045

Primary Malignant Tumors of the Mandible & Jaw Bone

Oral Cavity Squamous Cell Carcinoma (Bone Invasion Scenarios)

Odontogenic and Jaw-Specific Malignancies

Specific Histologic Types (Use with Morphology/Behavior Context)

Osteoradionecrosis (ORN) — Major Comorbidity

Complicating Diagnoses & Comorbidities

Staging / Encounter-Specific Codes

🏨 MS-DRG Mapping

Head & Neck Oncologic Procedures

Musculoskeletal — Head/Facial Bone Procedures

Oral & Dental Procedures (when principal diagnosis is odontogenic)

🌳 CPT Code Tree — Mandible Tumor Excision Family

🗂️ ICD-10-PCS Context (Inpatient Coding)

ICD-10-PCS Root Operations for 21045-Type Procedures

📝 Coding Examples

Example 1 — Floor of Mouth SCC with Mandibular Invasion (Otolaryngology / Head & Neck)

Example 2 — Osteosarcoma of Mandible (Oral Maxillofacial Surgery)

Example 3 — Ameloblastic Carcinoma with Graft Reconstruction

Example 4 — Mandibular Resection with Free Fibula Flap (Complex Reconstruction)

Example 5 — Return to OR During Global Period (Hardware Failure)

Example 6 — Staged Reconstruction (Bone Graft, Second Stage)

⚠️ Common Coding Pitfalls

📚 Brief Source References

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