Malignant Fibrous Histiocytoma of Bone






  • Metaphysis or diaphysis of long bones, especially around the knee.


  • Femur, tibia, and humerus are, in this order, the more frequent locations.


  • Pelvis, especially the ilium, follows in frequency.


  • About any other bone can be more rarely affected.




Clinical Symptoms and Signs






  • Local pain and/or the presence of a mass is the initial symptom that can present as early as 1 week to several months.


  • Pathologic fracture may occur.


  • As this tumor is frequently associated to a preceding disease, there may be symptoms related to the primary condition.


Image Diagnosis



Radiographic and CT Features






  • Radiographic and CT findings correspond to a high-grade malignant lesion usually located in the metaphysis or diaphysis of a long bone.


  • Lytic, with no mineral deposits or ossification, poorly circumscribed, with early cortical destruction and extension to soft parts.


  • Periosteal reaction is unusual.


  • Evidence of a preceding disorder may be seen.


MRI Features






  • MRI shows a lesion hypo- or isointense to muscle on T1-weighted images, high signal intensity on T2, and contrast enhancement, especially at the periphery of the tumor.


Bone Scan






  • Bone scan demonstrates a hot lesion.


Image Differential Diagnosis



Osteosarcoma, in Young Patients






  • In the absence of discernible mineralized tissue, it may be impossible to differentiate by image methods.

All the following tumors may also present very similar imaging features when a single lesion is considered:



  • Fibrosarcoma, high grade


  • Leiomyosarcoma, high grade


  • Angiosarcoma


  • Malignant primary lymphoma of the bone


  • Metastatic carcinoma


  • Myeloma




  • Signals of a preexisting lesion can suggest the diagnosis of MFH.


  • Presence of multiple lesions can suggest metastasis or myeloma, which have to be screened clinically.


Pathology



Gross Features






  • Usually a large lesion with undefined limits either intramedullary or in its eventual soft tissue extension.


  • Its cut surface varies from white and fibrous (collagen producing areas) to soft (cellular areas) to tan and yellowish (lipid-laden areas) to hemorrhagic and friable (necrotic areas).


Histological Features






  • Histologically, MFH is characterized by a mixed population of spindle cells, histiocytic-like cells, multinucleated giant cells, all of which, including the giant cells, may be very atypical, and a chronic inflammatory infiltrate.


  • Specific kinds of cells may predominate in certain areas.


  • Spindle cell areas present a storiform or cartwheel pattern.


  • Histiocytic-like cells may predominate, with large clear cytoplasm and atypical nuclei.


  • Atypical mitoses are frequent.


  • Some areas may be richly vascularized, sometimes in a hemangiopericytoma-like pattern.


  • Foci of inflammatory infiltration are a common finding.


  • Giant multinucleated very bizarre cells are seen and may be abundant.


  • Areas with a myxoid background may be seen.


  • In certain tumors, the presence of intercellular hyalinized collagen matrix may be impossible to tell from osteoid. Extensive sampling may be necessary to rule out this possibility.


Pathology Differential Diagnosis



Osteosarcoma






  • Always contains neoplastic bone trabeculae that must be sought extensively; may present nuclear positivity with SATB2.


Fibrosarcoma, High Grade






  • Absolute predominance of spindle cell population

Both differential diagnosis cited above may not be of clinical importance, since these tumors will probably be treated the same way.


Liposarcoma, Pleomorphic Type






  • Because of the foamy aspect of some neoplastic cells


Leiomyosarcoma, High Grade






  • Immunohistochemical methods may be necessary in difficult cases.


Metastatic Sarcomatoid Carcinoma






  • Clinical and immunohistochemical methods may identify a renal tumor and characteristic immunophenotype.


Malignant Lymphoma with Fibrosis






  • Look for eventual multicentricity.


  • Spindle cells are not atypical.

Jan 2, 2017 | Posted by in ORTHOPEDIC | Comments Off on Malignant Fibrous Histiocytoma of Bone

Full access? Get Clinical Tree

Get Clinical Tree app for offline access