Wallach's Interpretation of Diagnostic Tests: Pathways to Arriving at a Clinical Diagnosis (381 page)

   
Serum protein
may be elevated, and hypogammaglobulinemia may be present.

   
Serum complement
levels may be decreased in HCDD.

   
Serum protein electrophoresis and immunofixation
reveal a monoclonal light chain (κ in 80% cases), heavy chain protein or both.

   
Urine protein electrophoresis and immunofixation
demonstrate M protein that is composed of urine light chain.

   
Serum free light chain immunoassay
altered κ:λ ratio.

   
Renal function tests
may be abnormal in cases with monoclonal light chain proteinuria. Increased serum creatinine is associated with poor prognosis.

   
Immunophenotype
: Plasma cells have immunophenotype similar to that described for plasma cell myeloma and MGUS.

Suggested Reading

Swerdlow SH, Campo E, Harris NL, et al.
WHO Classification of Tumours of Haematopoietic and Lymphoid Tissues
, 4th ed. Lyon, France: International Agency for Research on Cancer; 2008:209.

PLASMACYTOMA

   Definition

Plasmacytoma(s) refers to single (or multiple) monoclonal plasma cell tumors with no involvement of bone marrow or blood. There are no typical clinical features associated with plasmacytoma.

   Plasmacytomas are classified as either

  1.  Solitary plasmacytoma of bone (SPB), a localized bone lesion or

  2.  Extraosseous plasmacytoma (EP), localized plasma cell neoplasm that arise in tissues other than bone (upper respiratory tract, sinuses, larynx, GI system, lymph nodes, bladder, breast, thyroid, testis, parotid, CNS, and skin)

   SPB and EP constitute 3–5% of all plasma cell neoplasms. Approximately 75% of SPB patients progress to plasma cell myeloma (PCM), or additional bone lesions develop with a median survival of 10 years. Conversely, EP cases have better prognosis with only 15% progressing to plasma cell myeloma.

   Who Should Be Suspected?

Middle-aged patients with bone pain, pathologic fractures, or neurologic symptoms related to nerve compression should be suspected for SPB. Patients with EP usually present with epistaxis, rhinorrhea, and nasal obstruction related to the tumor mass. Other manifestations depend on the location of EP.

   Laboratory Findings