Osteoblastic Osteosarcoma With Diverse Histomorphology: Diagnostic Insights From SATB2 and CD56 Immunoexpression

Osteosarcomas (OS) are malignant neoplasms with a high mortality rate. Osteoid formations are the main element aiding diagnosis, with the jaws being the affected site for around 7% of cases. Jaw osteosarcomas (JOS) tend to present at a slightly older age and may have a better prognosis compared to those arising in the long bones. They often mimic other spindle cell sarcomas and pose significant diagnostic dilemmas due to their varied histomorphology. Here, we describe a male patient aged 59 years with a history of a week-old intraoral nodular growth in the upper right region who visited our outpatient department. Orthopantomography disclosed a hazy radiopaque mass in the maxilla, with histopathology showing cellular connective tissue comprising spindle cells, mitotic figures, giant cells, clear cells, osteoid formations, clear cells, and epithelioid and histiocytoid cells. Recurrence was noted after 1 year, and the patient underwent wide local excision. Immunohistochemistry (IHC) revealed focal positivity for smooth muscle actin (SMA) and epithelial membrane antigen (EMA); however, diffuse expression of sequence-binding protein 2 (SATB2) and cluster of differentiation 56 (CD56) supported the diagnosis of an osteoblastic variant of OS. The case highlights the diagnostic utility of SATB2 and the importance of a panel of markers approach in distinguishing osteoblastic OS from other histological mimics.