What is the likely diagnosis for a 52-year-old male with a multilocular radiolucency in the left mandible and histological findings of plasma cells?

The diagnosis of plasmacytoma is supported by the presence of plasma cells in the histological findings and the description of a multilocular radiolucency in the left mandible. Plasmacytoma is a neoplastic proliferation of plasma cells and can occur in the bone, presenting as areas of radiolucency. This localized form of multiple myeloma can explain the findings observed in the patient.

Multilocular radiolucencies, often described as "soap bubble" or "honeycomb" appearances on radiographs, are characteristic of various jaw lesions, but when coupled with histological evidence of plasma cells, plasmacytoma emerges as the primary diagnosis. In the context of oral and maxillofacial pathology, it is also critical to differentiate this from conditions such as osteosarcoma, ameloblastoma, or multifocal osteomyelitis, which have distinct histological and radiographic presentations.

In osteosarcoma, one would expect to see a different pattern of bone involvement and atypical mesenchymal cells rather than mature plasma cells. Ameloblastoma typically presents with a different cellular composition, primarily originating from odontogenic epithelium, and while it can appear multilocular, the histological