Types of Plasmacytoma
There are two main types of plasmacytoma: solitary bone plasmacytoma and extramedullary plasmacytoma.Histological Features
Under the microscope, plasmacytomas are characterized by a dense infiltration of
plasma cells. These cells typically have an eccentric nucleus, a perinuclear halo (due to the Golgi apparatus), and basophilic cytoplasm. Mitotic figures may also be observed, indicating a high rate of cell division.
Immunohistochemistry
Immunohistochemical staining is crucial for diagnosing plasmacytoma. Plasma cells in plasmacytoma typically express
CD38,
CD138, and
MUM1. Additionally, light chain restriction (kappa or lambda) can be demonstrated, supporting the monoclonal nature of the neoplasm.
Clinical Presentation
Patients with plasmacytoma may present with pain, particularly in the case of solitary bone plasmacytoma, or with a mass effect in the case of extramedullary plasmacytoma. Other symptoms could include
pathologic fractures, neurological deficits, or obstructive symptoms depending on the location of the mass.
Diagnostic Criteria
The diagnosis of plasmacytoma requires a combination of clinical, radiologic, and histologic criteria. Key diagnostic features include the presence of a localized mass of monoclonal plasma cells, absence of other systemic signs of
multiple myeloma (like anemia, hypercalcemia, renal insufficiency), and normal bone marrow biopsy except at the site of the lesion.
Prognosis and Treatment
The prognosis of plasmacytoma varies based on the type and location. Solitary bone plasmacytomas have a higher risk of progression to multiple myeloma compared to extramedullary plasmacytomas. Treatment options typically include
radiotherapy and surgery, with chemotherapy reserved for cases that progress to multiple myeloma.
Conclusion
Plasmacytoma is a localized neoplasm of plasma cells that can present in bone or soft tissue. Histological examination and immunohistochemical staining are critical for diagnosis. Treatment usually involves localized therapies, and the risk of progression to multiple myeloma is a key consideration in patient management.
