Myogenic, Lipogenic, and Epithelial Bone Sarcomas

Hannah D. Morgan

Leiomyosarcoma and liposarcoma of bone and adamantinoma are all rare osseous malignancies, each constituting less than 1% all bone sarcomas. Patients with leiomyosarcoma and liposarcoma of bone should be carefully examined to ensure that the bony lesion is a primary tumor and not a metastasis from a soft tissue malignancy. Adamantinoma should be always be considered in the differential diagnosis of a tibial aggressive lesion.

Pathogenesis

Etiology

Leiomyosarcoma: arises from smooth muscle cells of intraosseous blood vessels
Liposarcoma: etiology unknown; immature adipose tissue
Adamantinoma: presumed ectopic epithelial cell residues

Epidemiology

Leiomyosarcoma
- Extremely rare; <0.1% of all bone sarcomas
- Male = female
- First through ninth decades; mean age 45 to 50 years
- Femur/tibia > humerus > ilium in extragnathic sites
Liposarcoma
- One of the rarest primary bone tumors
- Second through sixth decades; typically third and fourth decades
- Major long tubular bones affected
Adamantinoma
- ∼0.4% of bone sarcomas
- Male:female 3:2
- Young adults and children (mean age 30 years); typically older than osteofibrous dysplasia
- 85% involve tibia (especially anterior aspect); 10% tibia and fibula

Pathophysiology

Leiomyosarcoma
- Spindle-shaped cells with eosinophilic cytoplasm and cigar-shaped nuclei arranged in bundles intersecting at right angles (Fig. 6.7-1)
- Immunohistochemistry: positive vimentin (as for all sarcomas), positive smooth muscle actin
Liposarcoma
- Either pleomorphic or round cell–rich high-grade lesion
- Signet-ring lipoblasts may be seen.
Adamantinoma
- Epithelial cells surrounded by spindle-shaped fibrous tissue; little pleomorphism (Fig. 6.7-2)