We illustrate an indirect measure for detecting abnormal immunoglobulin in a patient: the observation of unusual coloring of blood and bone marrow smears after panoptical staining. A 68-year-old male presented with dorsal bone pain for several months. The complete blood count was RBC 2.71 × 1012/l, Hb 9.7 g/dl, WBC 4.5 × 109/l, platelets 168 × 109/l. The blood cell analyzer (LH 750, Beckman, Villepinte, France) indicated no flags. The peripheral blood smear was stained according to the May-Grünwald-Giemsa procedure mixing methanol, cationic (basic) methylene azur and anionic (acidic) eosin with verified neutral pH of 7.2. It macroscopically showed moderate blue-gray staining as compared to the color typically seen in the laboratory (upper left Image 1). Under the microscope, an increased rouleaux formation of RBCs was observed. The bone marrow aspiration showed marked blue staining, suggesting high immunoglobulin concentration (upper right Image 1). It was infiltrated by 95% abnormal plasmocytes (proplasmocytes and some plasmablasts, below Image 1) with increased background staining, leading to the diagnosis of plasma cell myeloma. Serum electrophoresis found then a monoclonal gammapathy of IgG Kappa (IgG°: 32 g/L). The X-ray films of the skeletal series demonstrated lytic lesions from the vertebras.
Peripheral blood or bone marrow smears of patients with plasma cell myeloma may show unusual color appearance as compared with other smears stained in the same batch. An incorrect stain pH is more commonly the reason for an overly blue-appearing slide, but in plasma cell neoplasms, the particular color of the smear is related to the high immunoglobulin concentration increasing the uptake of the basic component of the stain .