Surgical Margins

By admin On Oct 11, 2024

Ovid: Oncology and Basic Science

Editors: Tornetta, Paul; Einhorn, Thomas A.; Damron, Timothy A.

Title: Oncology and Basic Science, 7th Edition

> Table of Contents > Section I
– Evaluation and Management of Musculoskeletal Oncology Problems > 4
– Treatment Principles > 4.1 – Surgical Margins

4.1

Surgical Margins

Robert Quinn

Appropriate surgical planning for the treatment of
musculoskeletal tumors requires proper histologic diagnosis and
staging. The type of surgical margin most appropriate for a given tumor
is, to a large extent, dictated by the appropriate stage.

Terminology

The pathologic definitions in Table 4.1-1 are essential to the understanding of surgical margins.

Surgical Margins

The surgical procedures and margins are defined in Table 4.1-2.

Surgical Procedures

Principles of Selecting the Appropriate Surgical Procedure

Selection of the most appropriate surgical margin is dependent upon the overall treatment goals of the patient.
Table 4.1-3 shows some example tumor types according to surgical stage for each type of surgical procedure.
If the goal of treatment is to establish
the best chance of cure, then the most appropriate margin is that which
will provide the lowest risk of local recurrence.
- Life-threatening malignancy: successful limb salvage is a secondary goal, and margins should not be
  
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  compromised in an effort to save a limb or improve its function.
- Most aggressive benign tumors: rarely
  life- or limb-threatening, and these are often best treated with a less
  aggressive procedure, accepting a low rate of local recurrence in
  exchange for improved functional outcome

Table 4.1-1 Terms Pertaining to Surgical Margins

Term	Definition
Reactive zone	Area, or potential area, between the tumor and normal tissue; it may be composed of variable amounts of pseudocapsule, satellite tumor lesions, and reactive tissue, including edema
Satellite lesion	Nodules of isolated tumor within the reactive zone
Skip lesion	Nodule of isolated tumor within the same compartment as the primary tumor but separated by an interval of normal tissue beyond the reactive zone

Table 4.1-2 Definitions of Surgical Procedures Related to Margins

Procedure	Definition
Intralesional	Procedure performed within the capsule or pseudocapsule of the tumor. This is generally a curettage type of procedure for bone tumors and piecemeal excision for soft tissue tumors. By definition, macroscopic disease is left behind. An intralesional margin is obtained when the plane of dissection passes within the lesion.
Extended intralesional	Procedure performed intralesionally but extended beyond the confines of the tumor reactive zone into normal tissue by use of mechanical or other adjunctive means. This usually applies to low-grade aggressive bone lesions, where the outer border of a standard curettage is extended mechanically with aggressive use of curettes, a high-speed bur, or both, into normal surrounding bone. The bone margin may also be extended by the use of chemical (phenol), electrical, or laser cauterization, thermal effect of curing bone cement, and freezing effect of liquid nitrogen.
Marginal	Procedure performed within the reactive zone of the lesion. This is typically an en bloc type of resection for soft tissue tumors such as excision of a lipoma. For intraosseous bone tumors, a marginal excision would be an “extended curettage.” For surface bone tumors, a marginal excision would be accomplished by simple excision of the lesion without any surrounding tissue. A marginal margin is obtained when the plane of dissection passes through the reactive zone. Microscopic disease may be left behind where portions of the tumor itself extend into the reactive zone or where satellite lesions are present. A marginal resection or amputation risks leaving satellite lesions behind.
Wide	Procedure performed entirely through normal tissue beyond the reactive zone. It reflects not the amount of normal tissue that makes up the margin but simply the presence of some amount of normal tissue between the reactive zone and the plane of dissection. A wide procedure only risks leaving skip lesions behind.
Radical	Procedure in which the entire compartment of origin is removed
Contaminated margin	If, during the process of performing a wide or radical resection, the tumor is inadvertently entered and local normal tissue exposed, the area is at increased risk for local recurrence of the tumor. If the at-risk tissues are then removed with a wide margin, the ultimate margin is said to be a contaminated wide margin. If the at-risk tissues are not removed, the ultimate margin is intracapsular.

Types of Surgical Procedures

Figures 4.1-1 and 4.1-2 illustrate the respective planes of dissection that would be performed with these types of resections and amputations.

Intralesional Procedure

Debulking or curettage of a tumor from within the tumor itself

Indications

This type of procedure may be performed for diagnosis (i.e., with an open biopsy), for cure, or for palliation.
- Biopsy
  - When surgery is to be performed for
    sarcomas with curative intent, the carefully planned biopsy is an
    acceptable initial intralesional procedure.
  - An intralesional margin obtained following resection is generally unplanned and unlikely to be curative.
- Palliation
  - An intralesional procedure might be
    performed in the presence of metastatic disease where the primary goal
    of surgery is palliation and the secondary goal is tumor removal.
  - Example: Impending pathologic fracture of the femur
  - Primary goal of the procedure is stabilization
    
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    with an intramedullary rod, but intralesional curettage of the tumor is performed for two reasons:
    - To allow further strengthening of the construct by replacing tumor with polymethylmethacrylate
    - To afford potentially greater efficacy of adjuvant radiation or chemotherapy

Table 4.1-3 Surgical Margins as a Function of Tumor Stage

Musculoskeletal Tumor Society Stage	Example		Typical Desired Surgical Margin
Musculoskeletal Tumor Society Stage	Bone Tumor	Soft Tissue Tumor	Typical Desired Surgical Margin
Benign 1 (latent)	Enchondroma, nonossifying fibroma, solitary eosinophilic granuloma, unicameral bone cyst	Lipoma, ganglion, giant cell tumor of tendon sheath	Intralesional
Benign 2 (active)	Aneurysmal bone cyst, chondroblastoma, osteoblastoma	Hemangioma, myxoma	Marginal
Benign 3 (aggressive)	Giant cell tumor	Fibromatosis (desmoid type)	Extended intralesional curettage (bone) or wide (soft tissue or expendable bone)
Malignant IA/B	Low-grade osteosarcoma, conventional chondrosarcoma	Low-grade soft tissue sarcoma*	Wide
Malignant IIA/B	High-grade osteosarcoma, Ewing sarcoma	High-grade soft tissue sarcoma	Wide
Malignant III	High-grade osteosarcoma, Ewing sarcoma	High-grade soft tissue sarcoma	Wide with metastatectomy for cure if resectable
*Some soft tissue tumors that may be considered low-grade sarcomas by some, such as atypical lipomatous tumor (low-grade well-differentiated lipoma-like liposarcoma), are most often excised with a marginal margin.

Figure 4.1-1
Magnetic resonance imaging of a soft tissue sarcoma in the adductor
compartment of the thigh demonstrating potential surgical margins.
Dissection along line a would constitute an intralesional margin, along line b would be a marginal resection, and along line c would be a wide margin. A radical margin would entail removal of the entire adductor compartment.

Residual Disease and Risk of Recurrence

By definition this type of procedure
leaves behind macroscopic, or at least microscopic, disease. This is
acceptable for benign nonaggressive lesions (stage 1 or 2), but it is
not desirable for aggressive benign or malignant lesions except when
palliation is the goal.
For many benign bone and soft tissue
tumors (enchondroma, nonossifying fibroma, eosinophilic granuloma),
this procedure will result in a very small risk of local recurrence.
For most malignancies, this procedure will result in a high rate of local recurrence.

Marginal Procedure

A more aggressive excision performed
through the reactive zone to minimize the amount of residual
microscopic tumor, but leaving the potential for both satellite and
skip lesions
For soft tissue tumors an en bloc excision (“shell-out” procedure) is performed.

For more aggressive benign tumors of bone
(aneurysmal bone cyst, chondroblastoma, osteoblastoma) and even some
low-grade chondrosarcomas, acceptance of a marginal margin by way of an
extended intralesional curettage will result in a measurable risk of
local recurrence but not high enough to warrant the additional
morbidity of obtaining a wide margin except occasionally in expendable
bones such as the fibula, rib, or ilium.

Extended intralesional curettage
procedure: A marginal curettage is performed, and the margin is then
extended into the reactive zone or even into normal tissue mechanically
with a bur and~hor using cytostatic or cytocidal agents such as liquid
nitrogen, phenol, laser, or alcohol.

Figure 4.1-2
Magnetic resonance imaging of a high-grade osteosarcoma of the distal
tibia illustrating margins possible obtained at different levels of
amputation: intralesional (a), marginal (b), and wide (c). A radical margin would be obtained with a knee disarticulation.

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Amputations that achieve marginal margins
- May be performed as a palliative procedure
- May result from unsuccessful attempt at a wide margin amputation
- May be performed with plans to use adjunctive treatment to minimize recurrence

Wide Margins

When the plane of dissection passes
through normal tissue some distance beyond the reactive zone,
theoretically eliminating satellite lesions but potentially leaving
skip lesions behind

Indications

Cure: Appropriate margin to achieve cure
for majority of bone and soft tissue sarcomas, for occasional isolated
bone metastases (such as renal carcinoma), and for some particularly
aggressive benign tumors such as desmoid-type fibromatosis
Palliation: Occasionally wide resection
will also be performed for the treatment of metastatic disease when the
tumor is felt to be poorly responsive to other adjuvant measures.

Amputation With Wide Margins

Performed with curative intent when limb salvage is not indicated
When limb-sparing surgery would leave an
extremity with compromised vascularity or limited function inferior to
that which would be obtained with a prosthesis
If a patient would prefer amputation in
deference to the more complex nature of a reconstructive procedure and
the potential associated complications

Radical Resection

Removal of the entire compartment(s)
involved by the tumor, including the entire bone for bone tumors and
the entire muscle compartment from origin to insertion for soft tissue
tumors or soft tissue extension from bone tumors
Radical resections are largely of
historical importance but were thought to be necessary in some cases to
eliminate both satellite and skip lesions. In practice, skip lesions
are rare, probably represent metastatic disease, and can generally be
recognized on imaging studies provided the entire compartment is
visualized. Hence, prophylactic removal of the entire compartment
without evidence of skip lesions is rarely indicated.
- If the skip lesion is in close proximity to the primary, both will generally be resected with a single wide margin.
- If the skip lesion is more remote from
  the primary, two separate wide resections will generally suffice and
  often allow better functional outcome than a radical resection.