pathology

Definition

STS composed of malignant lipoblasts

Epidemiology

Common 

- 10% of STS

- second only to MFH

Occurs almost exclusively in adults

Males age 40-60

Can be multiple origin -> examine patient

Rarely arise from lipoma

Definition

Schwannoma

- benign tumour of nerve sheath

Epidemiology

Less common than neurofibroma

- occurs in adults

- can occur along any peripheral nerve

- also can occur along a nerve root

Usually a large nerve

More common in forearm

Seen in NF 2 

- acoustic Schwannoma

Definition

Cystic structure lined by a mature capsule of dense fibrous tissue

- contains thick viscous fluid with a high mucopolysaccharide content

- fluid is a myxoid degeneration of synovial fluid

Epidemiology

Most common in young females

- peak age 15-30

- F:M = 3:1

Most common tumour in hand (2/3)

Aetiology

Unclear

Aggressive Fibromatosis / Desmoid Tumour

Benign aggressive 

- most serious of all benign STT

Types

1.  Intra-abdominal 

- association familial polyposis coli & Gardner's syndrome

- aggressive infiltration

- death from retroperitoneal extension

2.  Extra-abdominal 

Non-metatasizing locally aggressive STT

Definition

Uncontrolled proliferation of single clone of plasma cells

Epidemiology

Most common malignant tumour of bone

Age 50-60

2-3 / 100 000

Pathology

Highly differentiated B lymphocytes

- associated with abnormality of protein synthesis

Usually bone marrow of entire skeleton involved

Definition

Developmental hamartoma in which areas of the skeleton fail to mature normally

- remain indefinitely as immature, poorly mineralized trabeculae

Pathology

Hamartoma of bone and fibrous tissue

McCune - Albright's Syndrome

Rare triad of

1.  Fibrous Dysplasia

Definition

Langerhan's Cell Histiocytosis

- non-neoplastic disorder

- characterised by infiltration by histiocytic cells (Monocyte / macrophage lineage)

Group of granulomatous inflammatory processes of unknown aetiology

- involve the reticuloendothelial component of the bone marrow, parenchymal organs, and skin

Types 

E - H - L

Definition

Rare cartilage tumour 

Epidemiology

1% of bone tumours / rare

- typically in adolescents

NHx

Usually benign

- but aggressive / frankly malignant behaviour reported

- locally aggressive

- can have pulmonary metastasis

Location

Definition

Rare low-grade malignant tumour

- cell of origin unknown

Epidemiology

Usually second or third decade of life

Site

90% diaphysis of tibia 

Mandible

X-ray

Most common anterior cortex of tibia

Definition

Expansile pseudotumor of reactive hemorrhagic tissue arising in bone

- characterised by blood filled spaces separated by fibrous tissue

Types

Primary 50%

- arise de novo 

Secondary 50%

- in association with other tumours 

- probably secondary to haemorrhage into 1° tumour

- GCT / chondroblastoma / osteoblastoma / osteosarcoma