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CD117 (KIT) is a useful marker in the diagnosis of plasmablastic plasma cell myeloma
Etan Marks1, Yang Shi1, Yanhua Wang1
1Department of Pathology, Montefiore Medical Center/Albert Einstein College of Medicine, Bronx, NY, USA.
Insights
CD117 is a useful marker for distinguishing plasmablastic plasma cell myeloma (PPCM) from plasmablastic lymphoma (PBL). PPCM patients often show CD117 positivity, paraproteinemia, and bone lesions, unlike PBL patients.
Area of Science:
- Hematology
- Oncology
- Pathology
Background:
- Plasmablastic plasma cell myeloma (PPCM) is a rare multiple myeloma variant.
- PPCM can be mistaken for plasmablastic lymphoma (PBL), an HIV-related lymphoid neoplasm.
- Distinguishing PPCM from PBL is crucial for appropriate patient management.
Purpose of the Study:
- To identify factors differentiating PPCM from PBL.
- To evaluate the utility of CD117 as a diagnostic marker.
Main Methods:
- Retrospective analysis of PPCM and PBL cases.
- Utilized data mining (Clinical Looking Glass) for patient identification.
- Assessed CD117 expression, paraproteinemia, bone lesions, HIV status, and EBV status.
Main Results:
- CD117 positivity was observed in 6/8 PPCM patients but 0/8 PBL patients (P=0.007).
- Paraproteinemia was present in all PPCM patients (8/8) vs. 2/8 PBL patients (P=0.007).
- Lytic bone lesions were more common in PPCM (6/8) than PBL (1/8) (P=0.0406). HIV positivity was more frequent in PBL.
Conclusions:
- CD117 is a valuable marker for differentiating PPCM from PBL.
- Combined assessment of CD117, paraproteinemia, and bone lesions aids diagnosis.
- Accurate differentiation ensures appropriate prognosis and treatment strategies.
Aims:
Plasmablastic plasma cell myeloma (PPCM) is a rare morphological presentation of multiple myeloma, and can resemble plasmablastic lymphoma (PBL), a human immunodeficiency virus (HIV)-related lymphoid neoplasm, morphologically and immunophenotypically. The aim of this study was to retrospectively search for factors that could help to differentiate these two entities.
Methods And Results:
We used clinical looking glass, a data mining tool, to identify patients with a diagnosis of either PPCM or PBL with a CD117 test performed. We identified 27 cases from 16 patients in our institution with a diagnosis of either PPCM or PBL. There were 14 cases of PBL from eight patients and 13 cases of PPCM from eight patients. We found that six of eight patients with PPCM were positive for CD117, whereas no patients with PBL (0/8) showed positivity (P = 0.007 for patients). All (8/8) PPCM patients had a paraproteinaemia, whereas only two of eight PBL patients had a paraproteinaemia (P = 0.007). Lytic bone lesions were more indicative of a PPCM, with six of eight patients showing these lesions, and only one of eight PBL patients showing these lesions (P = 0.0406). HIV status was more likely to be positive in PBL patients, with six of seven patients showing positivity, and only one of five PPCM patients showing positivity (P = 0.072). Epstein-Barr virus-encoded RNA in-situ hybridization did not differentiate these two entities, with seven of eight PBL patients showing positivity, and two of five PPCM patients showing positivity (P = 0.2168).
Conclusions:
This study reveals that CD117 can be a useful marker to help differentiate PPCM from PBL and give the patient an appropriate prognosis and options for treatment.
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