Figure 1.

Diagnostic features and follow-up in a PEL patient. (a, b) Pleural fluid with hypercellular areas composed of discohesive, large, atypical cells characterized by a high nucleocytoplasmic ratio, occasional nuclear bilobation and eccentric nuclei with multiple peripheral nucleoli reminiscent of atypical plasma cells (magnification: a × 400 and b × 1000). (c–f) Pleural fluid cell block (H&E stain: c; immunohistochemistry d–f; magnification × 400) showing the discohesive atypical cells (c), expressing plasma cell marker CD38 (d) and EMA (e) but negative for CD45 (f). (g, h) Computed Tomography axial single slice showing pretreatment reaccumulation of the right pleural fluid after successful drainage (g) and significant improvement of the right pleural fluid after 8 months of treatment by lenalidomide (h).