FROM PATHOLOGY – RESEARCH AND PRACTICE
A rare type of mantle cell lymphoma (MCL) has features that are similar to those of Castleman disease, according to a recent report based on three patient cases.
Lymph node biopsies for these patients initially indicated histologic features consistent with those of plasma cell (PC)-type Castleman disease, reported Takuro Igawa, MD, PhD, of Okayama (Japan) University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, and his coauthors. Further work-up, including flow cytometric analysis and cyclin D1 immunostaining, showed features consistent with those of MCL.
“This rare type of MCL can mimic Castleman disease in the clinical setting and upon histological examination,” Dr. Igawa and his colleagues wrote (Pathol Res Pract. 2017 Sep 18. pii: S0344-0338[17]30684-2. doi: 10.1016/j.prp.2017.09.015 ). “These confusing characteristics can make the diagnosis challenging, and careful flow cytometric analysis is recommended when a histopathological diagnosis is made.”
The patients in the study, all male, were 51, 74, and 81 years of age. Each presented with systemic lymphadenopathy, along with abnormal laboratory findings that according to the investigators are not usually associated with B-cell lymphomas such as MCL, including anemia, polyclonal IgG hypergammaglobulinemia, and elevated levels of C-reactive protein.
In lymph node biopsy specimens, the MCL component was “masked by histological features of PC-type Castleman disease” such as interfollicular plasmacytosis and atrophic germinal centers, the researchers wrote.
However, further pathologic investigations revealed features that were “essential to distinguish these 3 cases of MCL from PC-type Castleman disease,” they added.
In particular, an abnormal B-cell population was found using flow cytometric analysis, while subsequent cyclin D1 immunostaining in all three cases showed abnormal B-cells primarily in the mantle zone that were positive for CD20 and CD5, both typically expressed by MCL, along with SOX11, which is an “excellent diagnostic marker for MCL, including atypical MCL,” the investigators wrote.
These case reports also provide some evidence that interleukin-6 (IL-6), which is thought to be a driver of Castleman disease, might also be implicated in the pathogenesis of this rare MCL variant. the researchers found that all three cases had positive IL-6 staining in the interfollicular areas.
If further studies confirm the role of IL-6 in this rare setting, “specific treatments other than chemotherapy could potentially be used for patients with MCL with features of Castleman disease, such as an anti-IL-6 receptor antibody (tocilizumab), which is already used for patients with Castleman disease,” they said.
