Updated: 9/20/2021

Pleomorphic Sarcoma of Bone (Malignant Fibrous Histiocytoma)

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https://upload.orthobullets.com/topic/8030/images/Case B - femur  -xray - Parsons_moved.jpg
https://upload.orthobullets.com/topic/8030/images/Case B - femur  - CT - Parsons_moved.jpg
https://upload.orthobullets.com/topic/8030/images/Histology A - high power - Parsons_moved.jpg
https://upload.orthobullets.com/topic/8030/images/mfht1.jpg
https://upload.orthobullets.com/topic/8030/images/mfht2.jpg
  • summary
    • Pleomorphic Sarcoma of Bone, formerly known as Malignant Fibrous Histiocytoma, are rare malignant histiocytic lesions of bone most commonly found in the metaphysis of long bones. Patients typically present between the ages of 20 to 80 with painful, regional masses. 
    • Diagnosis is made with biopsy showing pleomorphic spindle cells and histiocytic cells in storiform pattern.
    • Treatment is usually neo-adjuvant chemotherapy, limb salvage surgical resection, followed by adjuvant chemotherapy
  • Epidemiology
    • Incidence
      • comprises < 2% of all primary malignant bone tumors
      • second most common bone sarcoma in adults after chondrosarcoma
    • Demographics
      • affects individuals 20 to 80 years of age
        • highest rates of affected patients in 2nd to 4th decades
      • male > female (3:2)
      • more common in Caucasians than African Americans or Asians
    • Anatomic location
      • 75% of cases from appendicular skeleton
      • often metaphysis of long bones
        • primarily distal femur, proximal tibia, proximal humerus
    • Risk factors
      • 25% arise as secondary lesion from bone infarct, Paget disease, or prior radiation
  • Etiology
    • Genetics
      • mutations of the tumor suppressor gene p53 have been implicated in tumorgenesis of secondary MFH of bone
  • Presentation
    • History
      • new, painful mass
      • can present with pathologic fracture
    • Symptoms
      • pain
      • constitutional symptoms
        • fevers, chills, night sweats and weight loss
    • Physical exam
      • inspection
        • swelling
        • limp
      • motion
        • decreased range of motion
  • Imaging
    • Radiographs
      • recommended views
        • AP and lateral of affected area
      • findings
        • lytic and destructive lesion often in the metaphysis
        • variable periosteal reaction
        • cortical destruction with soft tissue extension
        • radiographs often non-specific
    • MRI
      • indications
        • necessary to better characterize lesion
      • findings
        • deep seated heterogeneous mass
        • often associated with internal hemorrhage
        • T1- low signal
        • T2- high signal
    • CT scan
      • indications
        • CT chest used for staging to assess for pulmonary mets
        • to assess the amount and character of bone destruction
    • Bone scan
      • indications
        • may be ordered as part of pre-treatment staging
      • findings
        • shows increased uptake in adjacent cortex
  • Studies
    • Labs
      • elevated WBC
      • eosinophilia
      • abnormal LFTs
      • hypoglycemia
    • Histology
      • pleomorphic spindle cells and histiocytic cells in storiform pattern
      • malignant multinucleated giant cells with grooved or indented nuclei
      • areas of chronic inflammatory cells
      • variable collagen production
      • fibrous fascicles radiate from focal hypocellular areas
      • hemorrhagic and necrotic regions not infrequent; suggest high-grade lesion
  • Differential
    • Differential of Pleomorphic Sarcoma of Bone
      Malignant destructive lesion in older patient
      Sacral lesions in older patients
      Treated with wide resection and chemotherapy
      MFH / fibrosarcoma
      Chondrosarcoma
      Dedifferentiated chondrosarcoma
      Metastatic disease
      Lymphoma
      Myeloma
      Secondary sarcoma
      Osteosarcoma
      Chordoma
      Ewing's
      Rhabdomyosarcoma (soft tissue)
  • Treatment
    • Operative(similar to osteosarcoma)
      • neoadjuvant chemotherapy, wide resection, postoperative chemotherapy +/- radiation
        • indications
          • standard of care
        • chemotherapy
          • preoperative chemotherapy given for 8-12 weeks followed by maintenance chemotherapy for 6-12 months after surgical resection
        • surgical resection
          • correct surgical option is based on the location of the tumor and the feasibility of obtaining a wide surgical margin
            • wide excision or amputation have been found to have a higher 5-year survival rate than those who received intralesional or marginal excision
          • trend towards limb salvage whenever possible
            • options include arthroplasty, resection arthrodesis, allograft reconstruction and rotationplasty
        • radiation
          • indications
            • incomplete or questionable margins in order to reduce risk of local recurrence
            • adjunct to traditional chemotherapy and surgical regimens
  • Prognosis
    • 50% - 60% survival at 5 years
    • Worse prognosis with secondary MFH compared to primary lesions
    • Pulmonary metastasis common in up to 30%
    • Good response (> 90% tumor necrosis) to neoadjuvant chemotherapy found to have a much better prognosis
    • Age younger than 40 years associated with improved disease-free survival rate
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(OBQ12.25) A 75-year-old male presents with a slowly enlarging, painless thigh mass. Physical exam demonstrates a mass measuring approximately 7 cm in size. Figure A and B demonstrate a T1-weighted MRI and T2-weighted MRI respectively. The histologic findings from a biopsy are shown in Figure C. Which of the following is the most likely diagnosis.

QID: 4385
FIGURES:
1

Liposarcoma

7%

(373/5206)

2

Desmoid Tumor

15%

(763/5206)

3

Undifferentiated Pleomorphic Sarcoma

65%

(3360/5206)

4

Synovial sarcoma

8%

(407/5206)

5

Schwanoma

5%

(268/5206)

L 3 C

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