[Primary extraskeletal osteosarcoma: a clinicopathological study of ten cases]

Area of Science:

• Oncology
• Pathology
• Molecular Biology

Background:

• Extraskeletal osteosarcoma (ESOS) is a rare malignant tumor arising outside the bone.
• Understanding its clinicopathologic and molecular features is crucial for accurate diagnosis and treatment.
• Limited data exists on the comprehensive characterization of primary ESOS.

Purpose of the Study:

• To investigate the clinicopathologic features of primary extraskeletal osteosarcoma (ESOS).
• To determine the immunohistochemical profiles and molecular characteristics of ESOS.
• To aid in the differential diagnosis of this rare tumor.

Main Methods:

• Retrospective analysis of ten primary ESOS cases diagnosed between 2003 and 2019.
• Immunohistochemical staining for various markers (SATB2, α-SMA, EMA, Ki-67, etc.).
• Molecular analyses including FISH for MDM2/CDK4 amplification and mutation analysis for C-KIT and PDGFR-α.

Main Results:

• Ten ESOS cases (3 female, 7 male; age 36-85) with tumors ranging from 5.5-17.5 cm.
• Histology showed spindle cells, neoplastic osteoid, and cartilage; immunohistochemistry revealed SATB2 positivity (9/9).
• No MDM2/CDK4 amplification, SSX18 rearrangement, or C-KIT/PDGFR-α mutations were detected.

Conclusions:

• Primary ESOS is an extra-osseous osteogenic tumor.
• Diagnosis relies on clinical, radiological, and pathological findings.
• Immunohistochemistry (SATB2 positivity) and molecular profiling are valuable diagnostic tools.