Tumors

Question 1

benign lesions

Answer 1

1 = latent lesion e.g. non-ossifying fibroma enchondroma

2 = active lesion e.g. ABC, UBC , chondromyxoid fibroma, chondroblastoma

3 = aggressive lesion , e.g. giant cell tumor of bone

Question 2

Malignant lesion

Answer 2

Stage Grade Site

1. Metastasis IA Low Grade T1 - intracompartmental M0 (none)
2. IB Low-Grade T2 - extracompartmental M0 (none)
3. IIA High-Grade T1 - intracompartmental M0 (none)
4. IIB High-Grade T2 - extracompartmental M0 (none)
5. III Metastatic T1 - intracompartmental M1 (regional or distant)
6. III Metastatic T2 - extracompartmental M1 (regional or distant)

Question 3

Mirels’ criteria

Answer 3

Score 1 2 3

Site upper limb lower limb peritrochanteric

Pain mild moderate functional

Lesion blastic mixed lytic

Size < 1/3 1/3 to 2/3 > 2/3

Question 4

Biopsy priciples

Answer 4

• A biopsy should be regarded as the final diagnostic procedure, not a mere shortcut to diagnosis. Therefore, biopsies should always be preceded by primary diagnostics such as medical history, clinical examination, primary imaging studies such as X- rays and simple blood tests, and special diagnostic studies (MRI, PET).
• A useful medical history should include start, nature, and duration of symptoms.
• A possible familial predisposition should be questioned (e.g. in multiple hereditary exostoses or neurofibromatosis).
• The clinical examination consists of inspection and palpation to get an idea of the extent, the consistency of the swelling, its size and relation to neighbouring structures.
• Whole-body inspection is necessary as, for example, detection of cafe-au- lait spots would help lead to a diagnosis of neurofibromatosis.
• Primary imaging studies of a suspected bone tumour comprise X-rays of the affected region in two planes. When these primary diagnostic procedures still leave the suspicion of a musculoskeletal tumour, secondary or special diagnostic procedures are indicated. The importance of MRI for the investigation of bone and soft tissue tumours is unchallenged.
• To perform a representative and technically adequate biopsy, the following are necessary:
  
  • Detailed imaging not older than 4 weeks
  • Preoperative planning Before performing a biopsy one should think about how to resect the tumour should turn out to be malignant.
  • The biopsy tract is assumed to be contaminated with tumour cells and has, therefore, to be resected with wide margins, as the primary tumour itself.
  • This means that the surgeon doing the biopsy should be familiar with how the definitive surgery will proceed. The safest situation is for the biopsy to be performed by an orthopaedic oncologist who will deliver the ultimate treatment.
  • Two types of biopsies exists ⁃ closed biopsies (e.g. core needle biopsies) ⁃ open biopsies (excision or incisional biopsies). ⁃ Core needle biopsies (CNB), using a 14-gauge needle are reliable techniques for bone and soft tissue tumours. Although sensitivity and specificity have been reported to be similar to open biopsy other authors report high rates of diagnostic errors for closed biopsies.
  • The decision whether to perform a closed or an open biopsy should be based on individual patient factors, including location, suspected tumour type and homogeneity of the tumour, and according to the pathologist’s need/expertise.
  • Guidance by fluoroscope or CT for bony lesions is recommended to ensure that the area most suspicious of malignancy is chosen.
  • An incisional biopsy is preferably chosen when a closed biopsy is impossible or the result has been inconclusive or did not correlate with the clinical presentation and/or radiological findings.
  • Use the smallest longitudinal incision that will allow you to obtain enough specimen, obtain sufficient tissue and handle the tissue with care to avoid distorting the specimen’s texture, culture what you biopsy and biopsy what you the culture and use meticulous haemostasis.
  • When the diagnosis of a benign tumour is evident, an excisional biopsy may be performed, during which the whole tumour is resected. ▪
  • An intraoperative frozen section may be used (providing the expertise to interpret it is available) when it is not certain if only the reactive zone or tumour itself was biopsied.
  • Since a potential differential diagnosis always is a bacterial infection, and intraoperative bacteriology swab should be obtained.
  • The final diagnosis of a bone tumour should always be the result of a multidisciplinary discussion involving orthopaedic oncologists, musculoskeletal radiologists and musculoskeletal histopathologists.

Question 5

Osteoid Osteoma

Answer 5

• A small, discrete, painful, benign bone lesion pathoanatomy
• nidus - central nodule of woven bone and osteoid with osteoblastic rimming
• reactive zone - area of thickened bone and fibrovascular tissue cellular biology
• pain - attributed to increased local concentration of prostaglandin E2 and COX1 & 2 expression increased number and size of unmyelinated nerve fibers within the nidus

Question 6

Enchondromas

Answer 6

A benign chondrogenic tumor composed of hyaline cartilage located in the medullary cavity caused by an abnormality of chondroblast function in the physis

Question 7

Osteochondroma

Multiple Hereditary Exostosis

Answer 7

• A benign chondrogenic lesion derived from aberrant cartilage from the perichondral ring that may take the form of solitary ostoechondroma
• Multiple Hereditary Exostosis (MHE) hamartomatous proliferation of bone and cartilage possibly arise from growth plate cartilage that grows through the cortex by endochondral ossification , under the periosteum perichondral node of Ranvier
• defect may allow growth from the physis to extend from the surface the stalk of the lesion is cortical and cancellous bone formed from ossified cartilage mutation in EXT gene affects prehypertrophic chondrocytes of growth plate loss of regulation of Indian hedgehog protein is currently being investigated in the pathogenesis of this diseas
• Prognosis 5%-10% malignant transformation to chondrosarcoma in patients with MHE
  
  • proximal lesions more likely to undergo malignant transformation than distal lesions

Question 8

Chondroblastoma

Answer 8

A rare, benign chondrogenic lesion (differs from giant cell tumor by its chondroid matrix) Pathophysiology thought to arise from cartilaginous epiphyseal plate categorized as cartilage tumor due to its areas of chondroid matrix, but type II collagen is not expressed by tumor cells

Question 9

Chondrosarcoma

Answer 9

• Malignant primary bone tumor composed of chondrocytes with variable degrees of malignancy
• primary chondrosarcoma
  
  • low-grade
  • high-grade
  • dedifferentiated chondrosarcoma
  • clear cell chondrosarcoma
  • mesenchymal chondrosarcoma
• secondary chondrosarcoma arises from benign cartilage lesions including
  
  • osteochondroma (<1% risk of malignant transfomation)
  • multiple hereditary exostosis (1-10% risk of malignant transformation)
  • enchondromas (1% risk of malignant transformation)
  • Ollier’s disease (25-40% risk of malignant transformation)
  • Maffucci’s (100% risk of malignant transformation)

Question 10

multiple myeloma

Answer 10

• multiple myeloma is a neoplastic proliferation of plasma cells that presents with skeletal lesions neoplastic plasma cells produces immunoglobulins heavy chains: IgG (52%), IgA (21%), IgM (12%) light chains: kappa, lambda aka
• Bence Jones proteins disease takes multiple forms that vary in treatment and prognosis and includes
• multiple myeloma (see below)
• solitary plasmacytoma
• osteosclerotic myeloma

Question 11

non-ossifying fibroma (NOF)

Answer 11

• non-ossifying fibroma (NOF) is a benign fibrogenic lesion that is related to dysfunctional ossification
• one of the most common benign bone tumors in childhood (with osteochondroma)
• other names metaphyseal fibrous defect nonosteogenic fibroma cortical desmoid fibrous cortical defect fibromatosis fibroxanthoma

Question 12

UBC

Answer 12

• A non-neoplastic, serous fluid-filled bone lesion thought to result from temporary failure of medullary bone formation near the physis
• active - if cyst is adjacent to the physis
• latent - if normal bone separates cyst from physis

Question 13

ABC

Answer 13

A benign and non-neoplastic reactive bone lesion filled with multiple blood-filled cavities can be locally destructive to normal bone and may extend to soft tissue

Question 14

Tumour Excision

Answer 14

1. Intralesional - The path of excision passes through the pseudo-capsule (reactive zone) and directly into the lesion.
2. Marginal - The entire lesion is resected, with the plane of dissection in the pseudo-capsule around certain points around the lesion. This is represented as oedema on T2-weighted images
3. Wide (intracompartmental)
   The lesion is removed together with its pseudo-capsule and a cuff of normal tissue outside the field of oedema.
4. Radical

Question 15

GCT

Answer 15

• metaphyseal side of the physis, expanding into the epiphysis as a juxta-articular eccentrically placed lytic lesion with internal septation.
• Radiographic Features:
• well-defined lytic lesion that involves the metaphysis and epiphysis
• Treatment: essential to check calcium and phosphate to exclude brown tumour (primary hyperparathyroidism) prior to considering curettage and augmentation by bone graft/cement or cryosurgery. Consider resection or even amputation for recurrence or lesions demonstrating malignant features histologically.