Tumors and Tumor-Like Lesions

T. M. Link

5 Tumors and Tumor-Like Lesions

Definition

Primary bone tumors and tumor-like lesions comprise malignant and benign space-occupying lesions. They are relatively rare in the shoulder region. According to Barlow and co-workers, only 5% of all primary bone tumors are in the proximal humerus, scapula, and acromial end of the clavicle. Certain lesions, however, have a predilection for the shoulder. For instance, 51% of juvenile bone cysts occur in the shoulder region.

Clinical Findings

Pain

Swelling

Pathological fractures

Diagnostic Evaluation

General remarks

The age of the patient and location of the tumor are of utmost importance in diagnosing bone tumors:

Young patients up to age 30 years generally harbor benign or malignant primary bone tumors, while patients over age 50 years predominantly have secondary malignant bone tumors (metastases)

Typical bone tumors of older patients include plasmocytoma, chondrosarcoma, malignant fibrous histiocytoma, and lymphoma

Most tumors are located in the metaphyses, with the following exceptions:

Giant cell tumor, chondroblastoma, and clear cell chondrosarcoma are characteristically located in the epiphyses

Ewing sarcoma is characteristically located in the diaphyses

Juvenile bone cysts generally arise in the metaphyses and can grow into the diaphyses

Indications

Most important modality for diagnostic classification of bone tumors

Recommended views

Standard projections in two views

Special projections depending on the location of the tumor

Findings

Smoothly or indistinctly outlined osteolysis

Osteoblastic changes

Cortical destruction

Matrix calcifications or ossifications

Periosteal changes

Indications

Plays no significant role in tumors

Possibly for evaluation of soft-tissue component or joint effusion

Indications

Evaluation of the outline of a lesion

Cortical destruction (differentiating an enchondroma and low-grade chondrosarcoma)

Better evaluation of matrix changes

Assessment of mechanical stability

Recommended protocol (See p. 16, Standard Parameters)

Standard computed tomography (CT) or spiral CT:

– Section thickness: 2–5 mm

– Table feed: 2–5 mm/rotation

– Increment: 1–3 mm

Findings

Smoothly or indistinctly outlined osteolysis

Osteoblastic changes

Cortical destruction

Matrix calcifications or ossifications (more discernible and better evaluated than with conventional radiographic views)

Periosteal changes

Indications

Main indication is preoperative staging to evaluate articular invasion and neurovascular infiltration

Monitoring of malignant tumors undergoing chemotherapy

Limited role in establishing the diagnosis

For the diagnostic evaluation of cystic lesions: Detection of blood products, for example, in aneurysmal bone cyst and pigmented villonodular synovitis (PVNS)

Recommended sequences

T1-weighted spin-echo (SE) sequence (long axis)

T1-weighted SE sequence (long axis) with contrast enhancement

T2-weighted turbo spin-echo (TSE) sequence (short axis)

Fat-saturated T1-weighted SE sequence (short axis) with contrast enhancement

Short time inversion recovery (STIR) sequence (long axis)

T1-weighted SE or STIR sequence of the entire humerus with adjacent joints in malignant tumors to exclude skip lesions

Findings

T1-weighted SE sequence:

– Hypointense visualization of the tumor

– Cortical destruction

– Hypointense soft-tissue component

T2-weighted SE sequence:

– Hyperintense visualization of the tumor, possibly also hypointense depending on the extent of the sclerosis

– Hyperintense visualization of the bone marrow and the soft-tissue component

– Hypointense visualization of blood products (hemosiderin), as found in PVNS

T1-weighted SE sequence with contrast enhancement:

– Enhancement of solid tumors and cyst membranes

– Enhancement of the extraosseous soft-tissue component

– Enhancement of the bone-marrow edema

Fig. 5.1 Tumor location in the shoulder (n = 711)

Fig. 5.2 a, b Benign and malignant bone tumors of the shoulder

a Benign bone tumors (n = 494)

b Malignant bone tumors (n = 217)

ABC	Aneurysmal bone cyst
CB	Chondroblastoma
FD	Fibrous dysplasia
NOF	Nonossifying fibroma
O	Osteoid osteoma
GCT	Giant cell tumor

Location and Distribution of Primary Bone Tumors and Tumor-like Lesions

From 1974 to 1998, the Tumor Registry of the University of Munster, Germany, recorded and analyzed 711 tumors:

Of these tumors, 602 were located in the humerus, 90 in the scapula, and 19 in the clavicle (Fig. 5.1). This distribution correlates well with the results of the review conducted by Barlow and co-workers, who found 75% of the tumors in the proximal humerus, 20% in the scapula, and 5% in the clavicle.

The average patient age at the time of diagnosis was 31.5 years.

69% of the recorded lesions were benign compared to 50% benign lesions found in the review conducted by Barlow and co-workers:

– The benign tumors included 143 osteochondromas, 115 juvenile bone cysts, 75 enchondromas, and 50 aneurysmatic bone cysts

– The remaining benign tumors included 25 fibrous dysplasias, 15 chondroblastomas, 13 osteoid osteomas, 12 giant cell tumors, and 11 nonossifying fibromas (NOF, Fig. 5.2 a)

Malignant tumors are less frequent:

– The malignant tumors included 72 osteosarcomas, 52 chondrosarcomas, and 46 Ewing sarcomas (Fig. 5.2 b). Primary lymphomas of the bone were found in 10 cases

– Focal plasmocytomas with primary manifestation in the shoulder were found in 20 cases

– The tumor can be judged to be probably benign or probably malignant by its outline on the conventional radiograph (Figs. 5.3, 5.4)

Fig. 5.3 Lodwick’s classification for estimating growth rates of focal bone lesions

IA lesions are sharply defined osteolytic lesions located within the bone. IB lesions are sharply defined osteolytic lesions with cortical expansion and thinning. IC lesions show cortical destruction in the presence of a relatively smooth edge. Grade II lesions have a poorly defined outline and show cortical destruction. Grade III lesions are permeative, motheaten-like, aggressive lesions. The IA and IB lesions correspond to a pattern of slow growth rate (e.g., juvenile bone cyst) and the II and III lesions to a pattern of high growth rate (e.g., osteosarcoma). The IC lesions can have a slow or high growth rate, with the giant cell tumor a typical example.

Fig. 5.4 a, b Lodwick IB and II lesions

a Sharply defined Lodwick IB lesion, histologically corresponding to a juvenile bone cyst.

b Poorly defined Lodwick II lesion, histologically corresponding to metastatic bone lesion (from a renal cell carcinoma).

Benign Bone Tumors

Osteochondroma

Goals of Imaging

Visualization of the osteolytic or osteoblastic lesion (with conventional radiography or computed tomography [CT])

Detection of matrix changes (with conventional radiography or Visualization of periosteal reaction (with conventional radiography or CT)

Detection of cortical destruction (with conventional radiography or CT)

Relationship of the tumor to the joint (with magnetic resonance imaging [MRI])

Relationship of the tumor to vessels and nerves (with MRI)

Therapeutic Principles of the Osteochondroma

Resection if symptomatic or causing complications, for example, damage to vessels or nerves, fractures, bursitis

Resection also when the tumor is growing and if desired by patient, prophylactically or if located close to the axial skeleton

Resection along the margin, usually including the base

Recurrences originate in the region of the cartilaginous component and generally occur only in children, thus surgical intervention preferably after puberty

Definition

Most common benign bone lesion

Cartilage-forming tumor

Osseous projection with cartilage cap

Located in the shoulder in 22 % of cases

In the presented patient material, of 143 osteochondromas, seven were located in the clavicle, 39 in the scapula, and 97 in the humerus

Average age of patients: 19.3 ± 14.9 years

Pathology

Osteochondromas can be broad-based (Fig. 5.5) or on a stalk (Fig. 5.6)

While malignant transformation is rare for osteochondromas on a stalk, it is more frequent in sessile osteochondromas

Histologically, osteochondromas show a cartilaginous cap and an osseous component that connects with the underlying bone

The osseous component is histologically identical to the structure of healthy bone

The thickness of the cap is an indication for a possible malignant transformation: a width exceeding 2–3 cm is suspicious for malignant transformation (frequent in the shoulder)

Furthermore, irregular calcifications away from the base of the lesion are suspicious for malignant degeneration

Clinical Findings

Usually asymptomatic

Rarely, symptomatic due to pressure on muscle, bone, nerves, or vessels

Rarely, inflammatory changes in an exostotic bursa (bursitis) overlying the cartilage cap

Diagnostic Evaluation

Findings

Typical picture of broad-based or stalked exostosis

Occasional calcifications in the cartilage cap

Adjacent bone can be deformed or show growth disturbance

In general, no further imaging necessary to establish the diagnosis

Indications

Method of choice to determine the width of the cartilaginous cap if malignant transformation is suspected

Fig. 5.5 Osteochondroma of the humerus

Sessile osteochondroma of the proximal humerus in an 11-year-old boy.

Fig. 5.6 Osteochondroma of the scapula

Tangential view of the scapula with stalked osteochondroma of the scapula in an 18-year-old male patient.

Juvenile Unicameral Bone Cyst

Definition

Simple juvenile unicameral bone cysts are relatively common, typically located in the region of the shoulder (51%)

The preferred site is the proximal metadiaphyseal region of humerus, with rare extension of the cyst into the epiphysis

In the presented patient material, all 115 unicameral bone cysts were in the humerus, with no lesions found in the scapula or clavicle

Average age of patients: 13.8 ± 9.7 years

Pathology

Smoothly marginated cyst formation

The lining membrane consists of a few cells and can measure up to 1 cm (Fig. 5.7 a)

Surgical curettage essentially produces no solid tissue

The cyst fluid has an elevated concentration of alkaline phosphatase

Clinical Findings

Pathological fractures are frequent and are the first symptom in 70% of cases of this nonneoplastic condition (Fig. 5.7 b)

Not infrequently, pain, swelling, and restricted mobility of the shoulder joint Diagnostic Evaluation

Diagnostic Evalution

Findings

Located centrally in the bone

Not infrequently, intersecting lines traversing the cyst

Marginal sclerosis (Fig. 5.7 b)

Generally causing only a moderate expansion of the bone

Periosteal reaction only after fracture

In 20%, a fallen cortical fragment (“fallen leaf sign”) indicative of a fracture

Radiographic finding usually so unequivocal that additional imaging studies are not necessary

Indications

If inconclusive due to superimposition or atypical presentation

Indications

Reserved for unclear cases

Findings

Typical signal of a cyst with hypointensity on T1-weighted and hyperintensity on T2-weighted images

Smooth demarcation

Therapeutic Principles

Therapy only with fracture or if at risk for fracture

No therapy if cortex is maintained and strong, or after puberty

Curettage, filling with spongiosa chips, but up to 30% recurrence

Alternatively, evacuation of cyst with two needles and injection of corticosteroids every two months, three to five times (according to Campanacci, 1999)