Plasma cell myeloma with histiocyte-like morphology

Excerpt

A 76-year-old man presented to our institution for systemic eczema, fatigue, and weight loss over the preceding 10 months. Laboratory findings showed red blood cell count 3.02 × 10¹²/L, hemoglobin 105 g/L, white blood cell count 2.57 × 10⁹/L, albumin 2.3 g/dL, and immunoglobulin 6.2 g/dL. Serum immunofixation electrophoresis confirmed immunoglobulin G (IgG)-κ paraprotein, and the serum IgG level was 2.0 g/dL. Bone marrow aspirate revealed 36% histiocyte-like cells with numerous closely spaced vacuoles of varying size (Fig. 1a ×400, insert ×1000). Bone marrow biopsy showed monotonous proliferation of large abnormal cells with striking vacuolated cytoplasm and nuclei adjacent to the cytoplasm (Fig. 1b). These cells were positive for CD138 (Fig. 1c) and κ light chain (Fig. 1d) and negative for λ light chain (Fig. 1e) and CD68 (Fig. 1f). Additional immunohistochemical staining results were as follows: CD38 (+), EMA (+), CD20 (−), CD79α (−), CD10 (−), cyclin D1 (−) and Ki-67 (+20%). Flow cytometric studies detected a kappa-restricted CD38 and CD138 plasma cell population making up to 25.4% of cells, which lacked CD19, CD10, CD22, CD20, CD79α, CD28, CD81, and lambda, and expressed CD117 and CD56. G-banded chromosome analysis of 20 metaphases revealed a 45, X, -Y [3]/46, XY [17] karyotype. A diagnosis of multiple myeloma was made. The patient was given four cycles of VCD regimen (bortezomib, cyclophosphamide, and dexamethasone), and achieved very good partial response (VGPR).

…