A 70 year old male has a pathologic fracture of femur. The lesion appears lytic on X-ray with a circumscribed punched out appearance. The curetting from fracture site is most likely to show which of the following?
Malignant cells forming osteoid bone
Diminished and thinned trabecular bone fragments secondary to osteopenia
Sheets of atypical plasma cells
Metastatic prostatic adenocarcinoma
Malignant cells forming osteoid bone