Related Experiment Video
Updated: May 15, 2026
Identifying, Diagnosing, and Grading Malignant Peripheral Nerve Sheath Tumors in Genetically Engineered Mouse Models
Published on: May 17, 2024
Undifferentiated Pleomorphic Sarcoma with Dual Smooth-Muscle and Osteogenic Differentiation Mimicking Plasma Cell
Arnav P Rathod1, Hrishikesh S Saodekar1, Yogesh B Rathod1
1Department of Orthopedics, Dr. Panjabrao Deshmukh Memorial Medical College and Hospital, Amravati, Maharashtra, India.
Introduction:
Pleomorphic sarcoma (PS) is a high-grade soft-tissue malignancy with marked morphologic variability. Divergent differentiation is recognized, but dual smooth-muscle and osteogenic lineage differentiation is exceedingly rare and may mimic other malignancies.
Case Report:
A 52-year-old male presented with progressive low-back pain, weight loss, and an enlarging iliac mass. Magnetic resonance imaging showed multiple lytic lesions suggestive of plasma-cell dyscrasia; however, serum electrophoresis was negative. Histopathology revealed high-grade PS, and immunohistochemistry demonstrated simultaneous positivity for smooth-muscle actin and osteocalcin, confirming dual smooth-muscle and osteosarcomatous differentiation. The patient was referred to oncology for multidisciplinary management.
Conclusion:
PS with dual divergent differentiation represents a rare diagnostic challenge. Clinical and imaging features may falsely suggest hematologic malignancy, underscoring the necessity of correlating radiology, histopathology, and immunohistochemistry.
