What are anatomical compartments?

The concept of anatomical compartments in the limb is attributed to Enneking. The idea is that these osteofascial envelopes tend to contain the growth of sarcomas and therefore consideration should be given to removing the whole compartment when operating. Furthermore, it is obvious that biopsies should not cross (and therefore contaminate) uninvolved compartments. Where these barriers are obvious, for example in the thigh, the tumour is said to be in an intracompartmental site. Other sites with less obvious barriers (for example the popliteal fossa) are classified as extracompartmental.

This concept is used in the MSTS staging system and the classification of surgical margins.

Examples of intra- and extracompartmental sites:

Intracompartmental sites Extracompartmental sites
Intra-articular
Superficial to deep fascia
Osteofascial compartments Extrafascial planes or spaces
– Ray of hand or foot – Mid- and hindfoot
– Posterior calf – Popliteal space
– Anterolateral leg – Groin/femoral triangle
– Anterior thigh – Intrapelvic
– Medial thigh – Mid hand
– Posterior thigh – Antecubital fossa
– Buttocks – Axilla
– Volar forearm – Periclavicular
– Dorsal forearm – Paraspinal
– Anterior arm – Head and neck
– Posterior arm
– Periscapular

Tumours which arise within a compartment and expand outside it are also classified as extracompartmental. For example, an osteosarcoma of the distal femur with an associated soft tissue mass would be classified as an MSTS 2B if not metastatic.

 

Limitations of this approach include the fact that although the margins of a compartment might be clear in an axial section, often the superior and inferior limits of the compartment are less well defined.

Referral guidelines for suspected primary bone tumours

NICE guidance suggests the following:

1.13 Bone cancer and sarcoma
General recommendations
1.13.1 A patient who presents with symptoms suggesting bone cancer or
sarcoma should be referred to a team specialising in the
management of bone cancer and sarcoma, or to a recognised bone
cancer centre, depending on local arrangements.
1.13.2 If a primary healthcare professional has concerns about the
interpretation of a patient’s symptoms and/or signs, a discussion
with the local specialist should be considered.
1.13.3 Patients with increasing, unexplained or persistent bone pain or
tenderness, particularly pain at rest (and especially if not in the
joint), or an unexplained limp should be investigated by the primary
healthcare professional urgently. The nature of the investigations
will vary according to the patient’s age and clinical features.
• In older people metastases, myeloma or lymphoma, as well as
sarcoma, should be considered.

Specific recommendations
Bone tumours
1.13.4 A patient with a suspected spontaneous fracture should be referred
for an immediate X-ray.
1.13.5 If an X-ray indicates that bone cancer is a possibility, an urgent
referral should be made.
1.13.6 If the X-ray is normal but symptoms persist, the patient should be
followed up and/or a repeat X-ray or bone function tests or a referral
requested.

The UK guidance on the management of bone sarcomas states the following:

The most common symptom of a primary bone tumour is pain which may be nonmechanical or night pain. The presence of bone pain at night should always be considered to be a “red flag” symptom leading to further investigation. The presence of bone swelling or a soft-tissue mass may occur later. The average duration of symptoms is 3 months although a history of 6 months or longer is not uncommon [1315]. The presence of pain or a palpable mass arising from any bone should cause concern and lead to further investigation of which a plain X-ray is the first investigation of choice. The presence of any of the following on the X-ray is suggestive, but not diagnostic of a bone tumour and should also lead to further investigation:
  • bone destruction,
  • new bone formation,
  • periosteal swelling,
  • soft tissue swelling.
Referral forms for the London Sarcoma Service can be found here.
The North of England Bone and Soft Tissue Tumour Service has a fax for urgent referrals: 0191 223 1328. A referral form for professionals can be found here.

References UK guidelines for the management of bone sarcomas. NICE referral guidelines for suspected cancer 2005

Neurofibromatosis Type 1

Neurofibromatosis 1 (NF1) is a common, inherited autosomal dominant disease

The birth incidence is between 1 in 2,500 and 1 in 3,000, with about half being the first in their families to be affected.

Diagnostic criteria are that you need two or more of the following:

  • 6 or more cafe au lait macules (>0.5 cm in children and 1.5cm in adults)
  • 2 or more cutaneous/subcutaneous neurofibromas or 1 plexiform neurofibroma
  • axillary or groin freckling
  • optic pathway glioma
  • 2 or more Lisch nodules
  • bony dysplasia (sphenoid wing dysplasia, bowing of long bone +/- pseudarthrosis
  • parent or child with NF1

Patients with NF1 are at risk of a number of problems including optic pathway gliomas, CNS tumours, hypertension and congenital heart disease.

Orthopaedic problems include:

  • bowing of long bones +/- pseudarthrosis
  • scoliosis
  • osteoporosis
Oncological problems include:
  • benign tumours (neurofibroma, glomus tumours)
  • malignant tumours (10% lifetime risk of malignant change in plexiform neurofibromas (to malignant peripheral nerve sheath tumour),  optic pathway gliomas, cerebral gliomas,  phaeochromocytoma, rhabdomyosarcoma, juvenile myelomonocytic leukaemia, breast cancer in women)
Specialist neurofibromatosis clinics do exist but are few in number.
Reference

					

The Musculoskeletal Tumour Society staging system

The MSTS (Enneking) staging system for sarcomas is another exam classic.  This is a very straightforward system which allows the user to describe the extent of the tumour locally and systemically. Tumours are either low grade (Stage 1, <15% risk of metastasis), high grade (Stage 2, >15% risk of metastasis) or metastatic (Stage 3).

Intracompartmental tumours are classified as “A” and extracompartmental tumours as “B”.

For example, an osteosarcoma of the distal femur, which has an associated soft tissue mass but no detectable metastases would be staged as “2B” in this system.

Other systems include the AJCC system for staging.

Reference:

Enneking WF, Spanier SS, Goodman MA. Current concepts review. The surgical staging of musculoskeletal sarcoma. J Bone Joint Surg Am 1980;62(6):1027-30.

The five presenting complaints of musculoskeletal tumours

According to Levesque et al in their excellent book “A clinical guide to Primary Bone Tumours”, the five ways in which patients with musculoskeletal tumours present are:

  1. A soft tissue mass
  2. A painless bony mass
  3. A bone tumour as an incidental finding
  4. A painful bone lesion
  5. A pathological fracture
The approach to each clinical scenario has a different emphasis.

Describing surgical margins

The description of surgical margins requires an understanding of the local behaviour of sarcomas. Classically, sarcomas grow centrifugally, and around the central tumour is a “reactive zone” comprising compressed normal tissues, inflammatory cells and small numbers of tumour cells. Tumours also tend to stay within osteofascial anatomical compartments. These concepts were popularised by Enneking, in the era before the widepsread availability of cross-sectional imaging.

The text-book answer is that surgical margins are described as follows:

  • Intralesional – when the resection passes through tumour
  • Marginal – when the resection passes through the reactive zone
  • Wide – when the resection passes through normal tissue
  • Radical – when the whole of the involved compartment is removed.

However, given that the majority of tumours are close to critical neurovascular structures for at least part of their circumference, most resections are technically marginal.  A more helpful description is often whether or not the margin is microscopically positive (tumour at or within 1mm of the resection margin) or microscopically negative.

The surgical margin achieved is the strongest predictor of the risk of local recurrence in several large series.

 

 

What is a tumour?

A growth or swelling, which enlarges by cellular proliferation more rapidly than surrounding normal tissue and continues to enlarge after the initiating stimuli cease. Usually lacks structural organization and functional coordination with normal tissues and serves no useful purpose to the host organism.

Examination of the patient with a musculoskeletal tumour

Examination of the patient with a musculoskeletal tumour differs a little from a routine examination of a limb. The aim is to look for findings which support your diagnosis.

When examining a mass, you should consider the following:

  • site
  • size
  • depth (superficial to deep fascia or involving/deep to it)
  • shape and surfaces
  • fluctuance
  • pulsatility
  • tethering of overlying skin
  • draining lymph nodes
Associated features might include:
  • lymphoedema
  • involvement of neurovascular structures
  • signs of malignancy elsewhere (eg abdominal masses)
  • involvement of an adjacent joint
  • other masses elsewhere (eg hereditary multiple exostoses)

Taking a history

Taking a history from a patient with a suspected bone or soft tissue tumour requires a different emphasis from the rest of orthopaedics. Particular features to note include:

  • Length of history (is this a preexisting mass that has changed?)
  • Rate of growth
  • Pain history (site, character, severity, radiation, modifying factors, periodicity – is there mechanical or night pain?)
  • Previous surgery at the site of interest (ie is this a local recurrence?)
  • History of  malignancy (could this be a metastasis?)
  • History of a predisposing condition (eg Hereditary Multiple Exostoses)
  • Previous radiotherapy
  • Family history (think  inherited disorders like Li Fraumeni syndrome)
  • Symptoms suggestive of malignancy (eg weight loss, lethargy)

Maffucci syndrome

Maffucci syndrome is a rare, non-inherited abnormality characterised by multiple enchondromas, bone deformity and vascular (occasionally lymphatic) malformations. The genetic defect is unknown. Ollier’s disease is a related condition in which there are multiple enchondromas, but no vascular malformations.

Enchondromas classically occur in the long bones and in the hands and feet, although involvement of the skull, ribs and vertebrae are described. The vascular malformations often appear as soft tissue masses with a bluish tinge in the skin, and are often partially calcified on x-ray.

The diagnosis is made clinically as there is no specific laboratory test, and patients may come to diagnosis at any age, depending on the severity of the condition.

The risk of malignancy is higher than in Ollier’s disease: the major concern is around the degeneration of enchondromas to central chondrosarcomas, but there can be associated malignancies including brain tumours and it is these which are possibly more likely to be life threatening. As with other rare syndromes estimating the absolute risk of malignancy is difficult: one study of seven patients reported that malignant change was a “certainty”, but this was a small study likely subject to referral bias. There appears to be a consensus that life expectancy is relatively normal.

Treatment tends to be symptomatic: large enchondromas may need curettage, particularly where hand function is impaired. Patients are followed for changes in symptoms or in the size of their enchondromas.

For an overview of enchondromatosis syndromes look at Pansuriya’s article.

The Orphanet entry for Maffucci syndrome can be found here.