Panel A: A microscopic image of a hematoxylin and eosin (H&E)-stained bone marrow biopsy from patient 3 (Roman numeral 3).d, showing hypocellular marrow with 50 percent cellularity. Panel B: A microscopic image showing rare plasma cells highlighted with CD79a immunostain. Panel C: A set of four flow cytometry scatter plots. The first plot shows CD45 versus side scatter (SSC-H) with all viable events. The second plot shows CD10 versus CD20 with CD19 plus events, where red dots represent cells positive for surface kappa light chain, blue dots represent cells positive for surface lambda light chain, and green dots represent mature T cells. The third plot shows CD10 versus CD38. The fourth plot shows CD38 versus CD45, highlighting rare plasma cells with bright CD38 expression. Panel D: A microscopic image of an H&E-stained bone marrow biopsy from patient 3 (Roman numeral 3).e, showing normocellular marrow with 90 to 95 percent cellularity. Panel E: A microscopic image showing the lack of plasma cells or B cells based upon CD79a staining. Panel F: A set of four flow cytometry scatter plots similar to Panel C, showing essentially absent B cells and plasma cells. Panel G: A microscopic image of an H&E-stained bone marrow biopsy from a 9-month-old age-matched control, showing normocellular marrow for age ( greater than 90 percent). Panel H: A microscopic image showing CD79a immunostain in the age-matched control. Panel I: A set of four flow cytometry scatter plots. The first plot shows CD45 versus SSC-H with all viable events. The second plot shows CD10 versus CD20 with CD19 plus events, highlighting abundant CD19 plus B cells, including maturing hematogones and mature B cells. The third plot shows CD10 versus CD38, highlighting plasma cells. The fourth plot shows CD38 versus CD45.
Rare-to-absent mature B cells/plasma cells in the BM of patients with SEPTIN6-related disease compared with the age-matched control. (A) H&E-stained section of BM biopsy from patient III.d collected at 9 mo of age (hypocellular with ∼50% cellularity). (B) Rare plasma cells are seen morphologically and highlighted with CD79a immunostain. (C) BM flow cytometry results showing rare mature B cells with polytypic surface light chain expression (representing 0.15% of nonerythroid cells) and rare plasma cells (with bright CD38 expression in the fourth plot, representing 0.004% of nonerythroid cells). First and fourth plots include all viable events; second and third plots depict CD19+ events; red = positive for surface κ light chain; blue = positive for surface λ light chain; green = mature T cells. (D) H&E-stained section of BM biopsy from patient III.e collected at 2 mo of age (normocellular with 90–95% cellularity). (E) Lack of plasma cells or B cells based upon CD79a staining. (F) BM flow cytometry results showing essentially absent B cells and plasma cells (color scheme same as panel C). (G) 9-mo-old age-matched infant being worked up for anemia of unclear etiology. H&E-stained section of BM shows normocellular marrow for age (>90%). (H) CD79a immunostain in the age-matched control. (I) Flow cytometry results from an age-matched control showing abundant CD19+ B cells including maturing hematogones (CD10+, teal), mature B cells (CD20+, teal), and plasma cells (bright CD38, yellow). Note: Histology photomicrographs at 400× magnification.