Chest Wall Invasive Diseases

Toms Franquet, MD, PhD

DIFFERENTIAL DIAGNOSIS

Common

Primary Tumors
- Lung Cancer
- Mesothelioma
Metastases

Less Common

Actinomycosis
Empyema Necessitatis
- Tuberculosis
Primary Rib Tumors
- Chondrosarcoma
- Osteosarcoma
Lymphoma
Soft Tissue Sarcomas
- Fibrosarcoma and Malignant Fibrohistiocytoma

Rare but Important

Primary Chest Wall Infection: Necrotizing Fasciitis
Primitive Neuroectodermal Tumor (Askin Tumor)
Deep Fibromatoses
- Aggressive Fibromatosis
- Musculoaponeurotic Fibromatoses
- Desmoid Tumors
Sternal Osteomyelitis

ESSENTIAL INFORMATION

Key Differential Diagnosis Issues

Consider clinical presentation, natural history, and patient age at presentation
Empyema necessitatis: Fluid collections in pleura and chest wall
Necrotizing fasciitis
- Signs of inflammation may not be apparent (early stage) if bacteria are deep within soft tissues
- Subcutaneous air (gas-forming organisms) commonly present
Chondrosarcoma is most common malignant primary bone tumor of chest wall in adults
Soft tissue sarcomas are indeterminate by imaging features
Fibromatosis may be component of Gardner syndrome (familial adenomatous polyposis)

Helpful Clues for Common Diagnoses

Lung Cancer
- Pancoast tumor: Traverses lung apex and may involve lower trunks of brachial plexus
- May involve pleura, intercostal nerves, adjacent ribs, and vertebrae
  - Findings of invasion: Rib destruction, encasement of nerves or blood vessels
Mesothelioma
- Circumferential pleural involvement (including mediastinal pleura)
- Pleural fluid 95%
- CT findings of chest wall invasion: Obscuration of fat planes, infiltration of intercostal muscles, periosteal reaction, and bone destruction
- May also invade mediastinum and diaphragm
Metastases
- Frequent history of primary tumor
- Common primaries: Lung, kidney, breast, and prostate

Helpful Clues for Less Common Diagnoses

Actinomycosis
- Rod-shaped bacterium, anaerobe, sulfur granules
- Traverses fascial planes from lung to pleura to chest wall
- May create fistulas
Empyema Necessitatis
- Mycobacterium tuberculosis
  - Contiguous spread from underlying pleural or pulmonary lesions
  - May create fistulas
Primary Rib Tumors
- Chondrosarcoma, osteosarcoma
  - Lesions can be osteolytic, osteoblastic, or both
  - Scattered flocculent calcifications
  - Large lobulated excrescent mass arising from rib
  - Chest wall extension: Soft tissue mass
Lymphoma
- Direct extension into anterior chest wall from anterior mediastinal lymph nodes
- Isolated chest wall lesions without direct extension can occur
- Chest wall mass with rib destruction: Lytic or sclerotic
- May grow around sternum or ribs without destroying them
Soft Tissue Sarcomas
- Fibrosarcoma and malignant fibrohistiocytoma
  - Malignant fibrous histiocytoma: Most common malignant soft tissue sarcoma in adults
  - Similar CT and MR appearances

Helpful Clues for Rare Diagnoses

Primary Chest Wall Infection: Necrotizing Fasciitis
- Rapidly spreading infection of subcutaneous tissue
- Uncommon but potentially fatal condition
- Tissue necrosis and gas formation
- Spontaneous or in patients with diabetes, immunosuppression, post trauma, or surgery
- Staphylococcus aureus, Pseudomonas aeruginosa
Primitive Neuroectodermal Tumor (Askin Tumor)
- Large chest wall mass in adolescent or young adult
- Rib destruction, pleural thickening or pleural effusion and focal invasion of lung
- MR should be performed to delineate soft tissue involvement
Deep Fibromatoses
- Aggressive fibromatoses
  - Can be very large with high tendency to recur after treatment
  - Rarely intrathoracic
  - CT features: Enhancing soft tissue mass that may be iso- or slightly hypodense to surrounding muscle
  - MR features: Isointense on T1-weighted images and heterogeneously hyperintense on T2-weighted images; shows bands of low signal on all sequences
- Musculoaponeurotic fibromatoses
  - Chest wall involvement (10-28%)
  - Solitary or multicentric
- Desmoid tumors
  - Soft tissue masses with poorly defined margins
  - Most frequently located in abdomen (50%)
  - Chest wall (8-10%)
  - Very rarely intrathoracic
Sternal Osteomyelitis
- Primary
  - Intravenous illicit drug users
- Secondary
  - After median sternotomy for cardiac surgery (0.5-5%)
  - CT is imaging method of choice
  - CT features: Irregularity of bony sternotomy margins, bony sclerosis, and peristernal soft tissue masses with abscess formation