25601 Plasma Cell Proliferative FISH, Tissue (PLASF)

17p- (17p deletion) or TP53, IGH (14q32) rearrangement, Monoclonal Gammopathy of Unknown Significance (MGUS), Multiple Myeloma, Plasma Cell Leukemia, t(4;14) - FGFR3/IGH, t(11;14) - CCND1/IGH, t(14;16) - IGH/MAF, t(14;20) - IGH/MAFB, +1q or 1q22

TI PLASFSO

​Supporting the diagnosis of plasmacytoma or myeloma when coordinated with a surgical pathology consultation.

​A reason for testing and pathology report are required in order for testing to be performed. Send information with specimen. Acceptable pathology reports include working drafts, preliminary pathology, or surgical pathology reports.

Submit only 1 of the following specimens:

Tissue: Submit a formalin-fixed, paraffin-embedded (FFPE) tumor tissue block. Blocks prepared with alternative fixation methods may be acceptable; provide fixation method used. 

Slides: For each probe set ordered, 2 consecutive, unstained, 5 micron-thick sections placed on positively charged slides, and 1 hematoxylin and eosin (H&E) stained slide.

This test is not approved by the US Food and Drug Administration and is best used as an adjunct to existing clinical and pathologic information.

Fixatives other than formalin (eg, Prefer, Bouin) may not be successful for fluorescence in situ hybridization (FISH) assays. Although FISH testing will not be rejected due to non-formalin-fixation, results may be compromised.

Paraffin-embedded tissues that have been decalcified may be unsuccessful for FISH analysis. FISH studies will usually be attempted. The pathologist reviewing the hematoxylin and eosin-stained slide may find it necessary to cancel testing.

A plasmacytoma is a localized proliferation of plasma cells that are cytologically and immunophenotypically identical to the plasma cell clones seen in myeloma. There are 2 primary types of plasmacytomas, solitary plasmacytoma of bone (SPB) and extramedullary plasmacytoma (EP).​

SPBs are a localized bone tumor comprised of plasma cells and account for about 5% of all plasma cell neoplasms. Common sites for SPBs are the vertebrae, ribs, skull, pelvis, femur, clavicle, and scapula. Patients often present with pathological fracture or bone pain near the lesion. Treatment is typically radiation therapy; at 10 years, 35% of patients appear to be cured, 55% develop myeloma, and 10% have local recurrence.

EPs are tumors of plasma cells that form in areas away from the bone and account for 3% to 5% of all plasma cell neoplasms. Approximately 80% of EPs occur in the upper respiratory tract. Less common locations include the gastrointestinal tract, bladder, testis, central nervous system, and skin. Treatment consists of radiation therapy. Regional recurrence develops in about 25% of patients, but development of myeloma is less frequent, occurring in only about 15% of patients.

Genetics of both types of plasmacytomas, while not extensively studied, appear to be the same as plasma cell myeloma.

Paraffin plasma cell fluorescence in situ hybridization (FISH) evaluation of bone marrow clot specimens is also important when a fresh bone marrow specimen is not available or is unsuccessful in the initial/diagnostic evaluation to document the genetic abnormalities associated with a patient's plasma cell clone.

​A neoplastic clone is detected when the percent of cells with an abnormality exceeds the normal reference range for a given probe set.

A positive result supports the diagnosis of a plasmacytoma or myeloma.

A negative result does not exclude the diagnosis of a plasmacytoma or myeloma.