Treatment of Recurrent Posttransplant Lymphoproliferative Disorder of the Central Nervous System with High-Dose Methotrexate

Figure 1

(A) Polymorphic PTLD. The nodal parenchyma is mostly effaced by a mixed population of small and large lymphocytes, immunoblasts, and plasma cells. (B) CD20 immunochemistry shows reactivity in residual follicles, as well as in scattered larger B cells outside of follicles. (C) In situ hybridization for kappa light chains shows scattered expression in plasma cells. (D) In situ hybridization for lambda light chains shows mild predominance of lambda expressing plasma cells over kappa. (E) Monomorphic PTLD: many cells resemble immunoblasts and plasmablasts with large nuclei, prominent nucleoli, and eccentric pink cytoplasm. (F) CD20 immunochemistry shows minimal expression, as CD20 is typically lost as B cells differentiate towards plasma cells. (G) Immunohistochemical stain for kappa light chains shows weak, nonspecific reactivity. (H) Immunohistochemical stain for lambda light chains shows strong cytoplasmic reactivity.