Tumors and Tumorlike Lesions of the Knee Joint

M. Breitenseher and M. Dominkus

5 Tumors and Tumorlike Lesions of the Knee Joint

Definition

Bone tumors can be divided into primary and secondary osseous tumors. The knee joint is the most common localization of primary tumors of the bone, occurring as malignant, potentially malignant, benign, or tumorlike lesions. The predilection for the knee joint is perhaps associated with this region having the most marked bone length growth. Prior to modern-day surgical methods and chemotherapy, osteosarcoma, for example, had a mortality rate of 75%, but today more than 75% of patients survive the disease.

Classification

primary bone tumors:

– malignant tumors

– potentially malignant tumors

– benign tumors

– tumor-simulating diseases of the bone

secondary bone tumors

Clinical Signs

pain

swelling

pathologic fractures

Diagnostic Evaluation

(→ method of choice)

primary method for detecting and diagnosing bone tumors

allows differential diagnosis (DD) from other diseases of the bone

allows evaluation of growth rate (aggressiveness) and thus the malignant/benign nature of the tumor according to the following three groups of morphological characteristics (Table 5.1, Fig. 5.1):

– osteolytic lesion form

– osseous reaction

– mineralization of the tumor matrix

together with tumor localization and patient age (Tables 5.2, 5.3) can in most cases enable specific tumor diagnosis

provides the basis for determining practical procedure:

– NOF (= don’t touch me lesion) no further diagnosis or therapy

– enchondroma or fibrous dysplasia: radiography and clinical surveillance

– other tumors: additional diagnostic imaging followed by histological evaluation

bone tumors are only rarely undetectable on radiographs

Role of Imaging

demonstration of osteolytic or osteoblastic lesions

detection of matrix changes

demonstration of periosteal reactions

detection of cortical bone destruction

demonstration of soft tissue components of the tumor

relation of tumor to the joint, i.e., possible detection of infiltration

Table 5.1 Important radiographic signs of bone tumor for evaluating rate of growth (from lowest to highest-IA to III) or benign/malignant nature (IA= benign to III = malignant) based on Lodwick

Lodwick grading system	Lesion form	Bone reaction
IA	geographic osteolytic lesion (A–C), sclerotic rim, intact compact bone	solid with sharp, smooth contour (A–C)
IB	narrowing of compact bone, shell-like ballooning
IC	complete penetration of compact bone
II	geographic and moth-eaten lesion	lamellar, onionskin appearance
III	moth-eaten and permeative destruction without geographic component	radial, spicular

Table 5.2 Age distribution of malignant bone tumors

Age in years	Entity
1	neuroblastoma
1–10	Ewing sarcoma
10–30	osteosarcoma, Ewing sarcoma
30–40	parosteal osteosarcoma, myeloma, fibrosarcoma
> 40	metastases, myeloma, chondrosarcoma

Table 5.3 Sites of predilection of primary bone tumors

Localization	Entity
epiphysis	giant cell tumor, chondroblastoma
metaphysis	chondrogenic tumors (chondroma, chondromyxoidfibroma, chondrosarcoma) osteogenic tumors (osteoid osteoma, osteosarcoma)
diaphysis	medullary tumors (Ewing sarcoma, reticulosarcoma, myeloma)

Localization

Entity

epiphysis

giant cell tumor, chondroblastoma

metaphysis

chondrogenic tumors (chondroma, chondromyxoidfibroma, chondrosarcoma)

osteogenic tumors (osteoid osteoma, osteosarcoma)

diaphysis

medullary tumors (Ewing sarcoma, reticulosarcoma, myeloma)

Fig. 5.1 a–e Typical osseous changes associated with bone tumors, classification based on Lodwick.

The images illustrate the stages in osseous destruction, corresponding to the rate of tumor growth and thus its benign/malignant nature.

a Example of Lodwick grade IA: circumscribed, well defined osteolytic lesion with sclerotic rim and unremarkable cortical bone, corresponding to absence of growth and therefore a benign lesion. This example shows fibrous dysplasia of the proximal tibia.

b Example of Lodwick grade IB: geographic osteolytic lesion with circumscribed narrowing of compact bone and shell-like expansion as a sign of a slow-growing lesion, primarily a sign of a benign lesion. The lesion shown here is an aneurysmal bone cyst (ABC) of the distal femur.

c Example of Lodwick grade IC: geographic osteolytic lesion with complete penetration of compact bone as a sign of medium-grade tumor growth. This may be a sign of either a benign or malignant bone tumor. The lesion shown here is a myeloma in the proximal tibia with an infection focus there and two in the distal femur.

d Example of Lodwick grade II: moth-eaten osteolytic lesion with geographic destruction and lamellar or onion-skin periosteal as a sign of rapid and aggressive growth. The lesion shown here is a fibrosarcoma of the proximal tibia.

e Example of Lodwick grade III: moth-eaten osteolytic lesion with no geographic destruction, but with a radial and spicular periosteal reaction, features of a rapidly growing, highly aggressive, and malignant lesion. This image shows an osteosarcoma in the distal femur.

(→ complementary method of choice)

second diagnostic step in diagnostic imaging evaluation, supplementary diagnosis, and differential diagnosis

definitive differential diagnosis of stress fractures and osteonecroses/bone infarction where radiological findings are uncharacteristic or where there is clinical suspicion of a tumor

can differentiate between solid, cystic, and fatty tissue

method of choice for locoregional staging (essential for the type of surgical approach and biopsy planning):

– exact tumor infiltration of bone and bone marrow

– joint infiltration with evaluation of joint capsule, ligaments, cartilage, and effusion

– involvement of vessel-nerve bundle

– spread of soft tissue tumor component and infiltration of adjacent soft tissue

suitable for follow-up with some limitations

reserved for specific indications

important for diagnosing osteoid osteoma as the nidus is best demonstrated on CT

valuable complementary examination of tumors in the pelvis, scapula, sternum (flat bones), and spine, lesions may be better detected and visualized

back-up method if radiography and MRI do not produce a diagnosis

detection of multifocal lesions such as metastases, multiple myeloma, skip lesions, or multiple manifestations of a primary bone tumor (e.g., Ewing sarcoma)

benign lesion activity (e.g., enchondroma)

Angiography

surgical planning, identification of anatomical variants and detection of tumor-related vessel displacement, compression, and stenosis

previously important evaluation of vascular tumors (demonstration of vascular malignancy with corkscrew vessels and vascular disruption) is being replaced by sectional imaging modalities

conventional catheter angiography currently being replaced by noncatheter MR angiography

Basic Treatment Strategies

surgical terminology (based on Enneking)

1 intralesional:

biopsy, curettage

2 marginal:

resection with a margin around the tumor capsule with out opening it

3 wide:

the tumor is completely covered with a margin of healthy tissue

4 radical:

excision of the tumor-containing compartment, often exarticulation

1 = with out a healthy margin

2–4= with a healthy margin

Malignant Bone Tumors

Osteosarcoma

Definition

most common primary bone tumor of the knee joint

knee joint (distal femur and proximal tibia) is the most common localization of osteosarcoma

manifestation typically in the second and third decades of life; second, smaller age peak in old age

Pathology

tumor cells characteristically produce osteoid

tumor cells are pleomorph, sometimes resembling osteoblasts, and often demonstrate mitoses

Rare forms:

telangiectatic osteosarcoma

– particularly aggressive form of osteosarcoma

– characterized by large blood-filled cavities separated by septa and only minimal osteoid formation

parosteal osteosarcoma (Figs. 5.5, 5.6)

– superficial osteosarcoma

– 5% of osteosarcomas

– osteoblastic lesion, sitting on the cortical bone surface

– histologically high level of structural differentiation

– better prognosis than the other osteosarcomas

– somewhat older patient age compared to other osteosarcomas

secondary osteosarcomas

– with underlying Paget disease

– with prior radiation treatment

Clinical Signs

increasing pain over weeks and months

pain projection and transmission

soft tissue swelling

pathologic fractures are uncommon

Diagnostic Evaluation (Figs. 5.2–5.6)

Recommended Radiography Views

important: long format with clinical suspicion of tumor to avoid “cutting off” tumor

Findings

diagnosis usually made on the basis of radiography; staging using MRI

typical radiography view demonstrates mixture of osteoblastic and osteolytic lesions

osteoblastic components are usually so characteristic that they lead to diagnosis

cortex destruction

periosteal reaction with lamellar pattern or, more commonly, radial periosteal reactions-with spicular or “sun-burst” outgrowths-marking aggressive, rapid tumor growth

metaphyseal localization

Fig. 5.2a, b Osteosarcoma on conventional radiographs.

Osteolysis in the metaphysic of the distal femur. The lesion border is not clearly demarcated and there is a mixed lamellar and spicular periosteal reaction.

Basic Treatment Strategies

preoperative and post-operative chemotherapy (= neoadjuvant chemotherapy) with the aim of the highest degree of tumor necrosis possible

wide or radical resection if needed with joint resection and replacement (tumor must be covered with healthy tissue all the way around, intraosseous safe zone ca. 5 cm)

use of modular prostheses or biological reconstructions

amputation rarely necessary these days and no more certain oncologically

Indications

best method for staging

evaluation of intraosseous infiltration based on sharp line between bone tumor and normal bone marrow

detection of soft tissue tumor component that can displace or even infiltrate adjacent soft tissue structures

infiltration of the joint:

– joint effusion is an inconclusive sign as this can also be present without infiltration

– joint infiltration typically occurs via the joint capsule and ligament apparatus

preoperative evaluation (especially important for the surgeon) of infiltration of the vessel-nerve bundle possible:

– decision to retain or replace nerve and vessels

– important: MRI can potentially overstage in this case

Recommended Sequences

axial view is most important for evaluating the vessel-nerve bundle because it allows for vertical orientation to the anatomical structures

T1-weighted spin-echo (T1 SE) sequence

T2-weighted (T2) SE sequence

contrast enhancement

short tau inversion recovery (STIR) or T1 SE sequences

Findings

T1 SE sequence:

– evaluation of the border between tumor and healthy bone marrow

T2 SE sequence:

– tumor characterization

contrast enhancement:

– detection of enhancing tumor vs. nonenhancing necrotic or cystic tumors

STIR or T1 SE sequences:

– exclusion of skip lesions (tumor manifestations near the tumor) in entire affected compartment

Fig. 5.3 a–e Osteosarcoma, radiography, and MRI.

a, b AP and lateral radiographs show a discrete osteolytic lesion in the proximal fibular metaphysis and epiphysis as well as a spicular periosteal reaction.

c–e MRI views, coronal T1 (c), coronal contrast-enhanced sequence (d) and axial fat-suppressed (e), show in addition to the radiographic image a clearly visible soft tissue tumor component, separated by a well defined border from the normal musculature of the lower leg.

Fig. 5.4 a–d Osteosarcoma, radiography, and MRI.

a A lateral X-ray projection shows marked ossifications in the proximal tibial metaphysis and epiphysis, typical signs of osteosarcoma.

b–d An MRI-coronal STIR sequence (b), sagittal T1 SE sequence (c) and sagittal contrast-enhanced sequence (d)–shows low signal areas in the bone marrow on T1 and T2, which correspond to sclerosis. At the same time, selected areas demonstrate with low signal on T1, high signal on T2, and are contrast-enhancing. There is only a tiny soft tissue tumor component, though there is intra-articular tumor infiltration near the anterior cruciate ligament.

Fig. 5.5a, b Parosteal osteosarcoma.

Pronounced and easily distinguishable extraosseous sclerosis on the dorsal aspect of the distal femoral metaphysic can be seen on AP (a) and lateral (b) projections with a wide area of contact with the cortical bone. The radiograph shows almost no destruction.

Fig. 5.6 a,b Parosteal osteosarcoma.

Calcifications and ossifications sitting on the distal femur, demonstrating an irregular shell-like structure, and causing uneven narrowing of cortical bone.

a radiograph.

b CT.

Chondrosarcoma

Definition

second most common primary malignant bone tumor