Plasmacytomas are tumors formed by a single mass of abnormal plasma cells, which are part of the immune system. While they can occur anywhere in the body, they represent a localized form of plasma cell disorders.
What Are Plasmacytomas?
Plasma cells are specialized white blood cells that produce antibodies to fight infections. Plasmacytomas develop when these cells become abnormal and grow uncontrollably, forming a single tumor, a localized manifestation within the spectrum of plasma cell disorders.
There are two types of plasmacytomas: solitary bone plasmacytoma (SBP) and extramedullary plasmacytoma (EMP). SBP forms a tumor in a single spot on a bone, often in the spine. EMP involves a single tumor in soft tissues outside the bone marrow, frequently found in the head and neck, including the sinuses and throat, but can appear anywhere.
While localized, plasmacytomas share similarities with multiple myeloma, a widespread cancer of plasma cells. Multiple myeloma involves abnormal plasma cells throughout the bone marrow, leading to multiple tumors. Plasmacytomas are singular lesions, distinct from multiple myeloma’s widespread disease. However, plasmacytomas can progress to multiple myeloma; approximately 50% of individuals with SBP and about 15% with EMP may develop multiple myeloma over time.
Identifying Plasmacytomas
Symptoms vary depending on the tumor’s location. For solitary bone plasmacytoma (SBP), localized bone pain is common. This pain can result from bone damage and may lead to fractures, particularly in the ribs, spine, femur, or pelvis. If an SBP is in the spine, it can compress nerves or the spinal cord, causing radiating pain, weakness, numbness, or issues with bowel or bladder control.
Extramedullary plasmacytomas (EMPs) often present as a palpable mass. Symptoms arise from the tumor pressing on surrounding soft tissues or organs. For instance, an EMP in the head and neck might cause nasal discharge, nosebleeds, difficulty swallowing, or headaches. If an EMP affects the sinuses, symptoms like nasal congestion and a reduced sense of smell can occur.
Diagnosis typically involves imaging studies, blood and urine tests, and a tissue biopsy. Imaging techniques like X-rays, CT scans, MRI, and PET scans locate the tumor, assess its size, and determine if it has caused bone damage or is pressing on adjacent structures. MRI is useful for evaluating soft tissue involvement, while CT scans better delineate bone erosions.
A definitive diagnosis relies on a biopsy of the suspected tumor to examine for abnormal plasma cells. To confirm it is a solitary plasmacytoma and not multiple myeloma, a bone marrow biopsy is often performed. This ensures less than 10% of the bone marrow is abnormal and there are no signs of widespread disease. Blood and urine tests also check for M proteins, abnormal proteins produced by cancerous plasma cells, which are typically lower than in multiple myeloma.
Treatment Approaches for Plasmacytomas
Treatment strategies are tailored based on the tumor’s type and location, aiming to eliminate abnormal cells, prevent progression, and manage symptoms. Radiation therapy is a common and effective primary treatment for both solitary bone plasmacytoma (SBP) and extramedullary plasmacytoma (EMP). It directs high-energy radiation to the tumor site to destroy cancer cells. For SBP, a typical radiation dose ranges from 40 to 50 Gy, often leading to high local control rates and symptom relief.
Surgery may be considered for accessible extramedullary lesions to remove the tumor or alleviate compression symptoms. For some EMPs, especially in the head and neck, surgery might be followed by radiation therapy. However, surgery is not indicated for SBP unless there is structural instability or neurological compromise.
Systemic therapies, such as chemotherapy or targeted drugs, are typically not initial treatments for solitary plasmacytomas but may be used in specific situations. Chemotherapy might be considered if the tumor is larger than 5 cm, has not responded adequately to radiation, or if there is progression to multiple myeloma. Newer targeted therapies, sometimes combined with radiation, show promise in improving outcomes and preventing progression. Regular monitoring after initial treatment is standard to detect recurrence or progression to multiple myeloma.