Contaminated margins


The “whoops” procedure was coined to describe a situation where a seemingly benign lump has been shelled out by a surgeon only to discover later that this was a sarcoma. Over the last decade, practicing as a full time musculoskeletal oncologist no single entity has resulted in more anxiety, second opinions, medico-legal overtones or panicked phone-calls in the middle of the night from patients and surgeons alike.

I have found that the best way to approach such a setting is firstly consider what the standard of care is if the tumor was resected knowingly and then work forwards understanding what is at stake and then filling in the blanks based on the best available literature. Unfortunately, most people tend to jump to the third step first and ultimately get lost- the literature in this regard is very confusing and not an area for the uninitiated physician let alone the lay-person to take on lightly.

Standard of care

Soft tissue sarcomas must all be resected with a good margin described as beyond the reactive zone. In practical terms this means that during a resection the sarcoma surgeon will feel around the tumor and resect beyond the point that the tissue feels firm. This is obviously not the kind of thing to be done without a significant amount of experience. The whoops procedure is necessarily within the reactive zone. This is usually what is termed a marginal excision and there may or may not be tumor left behind. If grossly the tumor itself has been cut through at the edges, this is an intra-lesional excision and tumor has definitely been left behind. Theoretically the marginally excised tumor is less likely to recur then the intra-lesionally excised tumor. In practical terms , however, they both have a high rate of recurrence and are considered insufficient for cure by musculoskeletal oncologists.

Next, not all soft tissue sarcomas are treated with radiation. Only high-grade sarcomas should be radiated and then only if the dimension is greater than 5 cm. Intermediate grade and low grade soft tissue sarcomas and those smaller than 5 cm are not radiated.

Chemotherapy is really only indicated in specific groups of soft tissue sarcomas for cure. These are specifically the pediatric sarcomas like rhadomyosarcomas and PNETs (peripheral neuroectodermal tumors or Ewing family tumors). In some sarcomas they may be worth using them especially in young patients (eg. synovial sarcoma, malignant fibrous histocytoma). Otherwise, they are not indicated unless they have metastasized and then they are used for palliation (ie. to prolong life).

What is at stake?

The tumor that has been shelled out has no margins and may be intra-lesionally excised. The immediate and pressing implication is that tumor has been left behind and will now grow back. Unfortunately, because the area has been surgically manipulated blood vessels and lymphatics are now open in the area and the whole area becomes like a sponge for remaining cells to spread into (Figure 1).

Figure 1. The MRI scans in these cases do not usually show any trace of tumor. At best one can only see the residue of the previous surgery if the MRI is done within 3 months of the "whoops" procedure. Usually this is seen as oedema of fluid around the old surgery (a). Rarely solid areas may be seen, but these may not be tumor deposits but may indicate suture material left from the last surgery (b). Based on these scans measurements are taken such that anycontaminated material (c) is surface marked onto the patient and the entire contaminated area removed en bloc.

This then leads to the questions that afflicted patients (and surgeons ask):

But it’s been removed right?

Perhaps most of it, but the remaining tissue will likely grow faster and spread.

Can’t I have radiation or chemotherapy instead of another operation?

The standard of care means that a wide margin is paramount and then maybe radiation if the tumor is greater than 5 cm and of high grade. Similarly, chemotherapy is not indicated as well in this context.

Can’t I just wait and see?

If you knew that a tumor has been left behind and could spread and kill you would you wait and see?

I’ve been told that I need an amputation.

This is defined by the confines of the tumor. Amputations are not always necessary.

I’ve been told that the repeat resection will have high morbidity.

In most such cases I have re-excised the morbidity is high in maybe 2 out of 5 cases. Again this is determined by the tissue around. For example in the buttock there is always more tissue that can be removed but in the finger, the finger may have to be lost.


The marginally excised tumor should at all costs be re-excised with proper margins. Many times residual tumor can be found (Figure 2) if one looks hard enough. By re-excising these tumors in a timely manner the patient’s survival prospects can be brought back in line with what is expected of a proper excision according to standard of care.

Figure 2. The same case as shown above, underwent the resection. The orthopaedic oncologist who has marked the most suspicious area with a suture is usually the best person to determine the highest risk area. This specimen which was 120 mm by 60 mm had a focus of tumor only 1 mm by 8 mm in size. This could very easily be missed by the pathologist if there is no indication given by the surgeon as to where the risky areas are.