Fibrosarcoma

Benign Fibrous Histologies

• Nodular fasciitis: rapid growth over several weeks, pain, tenderness. Plump mature fibroblasts. Self-limiting process; recurrence uncommon after excision
• Fibroma: nonspecific term. Dense fibrous nodule. Simple excision
• Elastofibroma: rare, slow-growing benign tumor. Typically lower portion of the scapula. Repetitive manual tasks. Considered reactive lesions. Swollen eosinophilic collagen and elastic fibers. Simple excision
• Superficial fibromatosis: arise from fascia or aponeuroses, small and slow growing
  • Palmar fibromatosis (Dupuytren's contracture) most common
  • Penile fibromatosis (Peyronie's disease) relatively rare, though more common in men who have palmar fibromatosis
• Deep fibromatosis: clinically diverse, deep-seated fibrous neoplasms
  • For more detail, please see the Desmoid tumor page

Fibrosarcoma Epidemiology

• 2-6% of primary malignant bone lesions
• Arise most commonly in tubular long bones, usually femur or tibia
• Most patients are 30-70; equal men and women
• Predisposing factors (~30% cases) include Paget's, fibrous dysplasia, osteomyelitis, bone infarcts, bone cysts, benign giant cell tumors, desmoplastic fibromas, or previous RT treatment

Natural History

• Locally aggressive
• Metastatic potential related to grade
  • High grade similar to osteosarcoma: 5-year OS ~25%
  • Low grade: 5-year (and 10-year) OS ~50%. Mets rate 5-15%
• Survival: 5-year 34%, 10-year 28%, 20-year 25%
• Children have relatively milder prognosis

Diagnosis

• Lytic with no reactive sclerosis
• High grade lesions show cortical destruction and periosteal reaction; sometimes with soft-tissue mass
• Radiographically very similar to osteosarcoma

Staging

• Please see the bone staging page

Treatment Overview

• Aggressive surgical resection
• Not considered highly radiosensitive, but RT recommended for inoperable tumors, residual disease, and palliation
• Perez (4th ed) recommends dosese 66-70Gy with shrinking-field technique