Veterinary Clinical Pathology ISSN 0275-6382 CASE REPORT Monoclonal gammopathy without hyperglobulinemia in 2 dogs with IgA secretory neoplasms Davis M. Seelig1, James A. Perry2, Anne C. Avery1, Paul R. Avery1 Departments of 1Microbiology, Immunology, and Pathology and 2Clinical Sciences, Veterinary Medical Center, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO, USA Key Words Abstract: Two dogs, an 8.5-year-old intact male Golden Retriever and a 10- B-cell lymphoma, immunofixation, year-old spayed female English Springer Spaniel, each with varied clinical immunoglobulin quantification, multiple histories, were referred to the Colorado State University Veterinary Teaching myeloma, serum protein electrophoresis Hospital for evaluation of hypercalcemia and severe anemia, respectively. In each dog, serum total protein and globulin concentrations were within refer- Correspondence Dr. Davis M. Seelig, Department of ence intervals. Cytologic examination of bone marrow aspirates from both Microbiology, Immunology, and Pathology, dogs revealed moderate to marked numbers of atypical lymphoid cells with Veterinary Medical Center, College of plasma cell features. Using serum immunofixation and serum immunoglob- Veterinary Medicine and Biomedical Sciences, ulin (Ig) quantification, a monoclonal Ig protein was identified. In conjunc- Colorado State University, 1619 Campus tion with other clinicopathologic and molecular findings, IgA secretory Delivery, Fort Collins, CO 80523, USA neoplasms, B-cell lymphoma with plasmacytoid features and multiple mye- E-mail: [email protected] loma (MM), were diagnosed. To our knowledge, these cases represent the first descriptions of IgA-secreting neoplasms in dogs that lacked hyper- DOI:10.1111/j.1939-165X.2010.00262.x globulinemia. In cases of suspected B-cell lymphoma or MM in dogs, serum proteins should be fully evaluated for the presence of a monoclonal Ig even in dogs that lack characteristic hyperproteinemia or hyperglobulinemia. This evaluation will aid in the diagnosis of secretory B-cell lymphoma or MM leading to appropriate clinical and therapeutic case management. Case Presentations 805, Radiometer America, Copenhagen Denmark). Urine was submitted for urinalysis. CBC abnormalities included moderate thrombocy- Dog 1 topenia (73,000/mL, reference interval [RI] 200,000– An 8.5-year-old intact male Golden Retriever of 500,000/mL) with occasional platelet clumps and giant 27.5 kg was presented to the internal medicine service platelets seen on the blood smear, moderately increased at the Colorado State University Veterinary Teaching mean platelet volume (24.8 fL, RI 7.5–14.6 fL), and Hospital (CSU-VTH) for evaluation of anorexia, leth- mild metarubricytosis characterized by 1 nucleated argy, polyuria, polydipsia, hypercalcemia, and throm- RBC (nRBC)/100 WBC (reference value 0 nRBCs/100 bocytopenia. Detailed history revealed that the dog WBC). Platelet clumping may have affected validity of had become increasingly lethargic, polyuric, and poly- the platelet count, but the interpretation of moderate dipsic over the previous 2 weeks and anorectic 3 days thrombocytopenia was supported by smear review. Fur- before presentation. On presentation, the dog was thermore, identification of giant platelets and increased quiet and no abnormalities were detected on physical mean platelet volume suggested increased thrombopoie- examination. Blood collected in tubes containing sis.1 The most significant biochemical result was EDTA and in plain tubes was submitted to the CSU- severe hypercalcemia (18.3 mg/dL, RI 9.2–11.7 mg/dL), Clinical Pathology Department for a CBC (Bayer Advia which was confirmed by an ionized calcium concentra- 120 analyzer, Seimens Corporation, New York, NY, tion of 2.2 mmol/L (RI 1.2–1.5 mmol/L). Other abnor- USA), serum biochemical profile (Hitachi 911, Roche- malities included mild azotemia, characterized by Boehringer Mannheim, Indianapolis, IN, USA), and increased urea (47 mg/dL, RI 7–32 mg/dL) and creati- measurement of ionized calcium concentration (ABL nine (1.6 mg/dL, RI 0.4–1.5 mg/dL) concentrations, mild Vet Clin Pathol 39/4 (2010) 447–453 c 2010 American Society for Veterinary Clinical Pathology 447 IgA secretory neoplasms in 2 dogs Seelig et al Figure 1. (A) Bone marrow aspirate from an 8.5-year-old intact male Golden Retriever (case 1) with hypercalcemia. Note many atypical, large immature lymphocytes with plasmacytoid features. Modified Wright–Giemsa stain; bar = 25 mm. (B) Immunofixation electrophoresis of serum from the Golden Retriever. There is a single restricted band in the IgA (A) well. The less intense, but identically migrating, band in the IgG lane is interpreted as cross- reactivity between IgG antisera and the light chain of the IgA monoclonal protein, as the antisera in the IgG lane is directed against both heavy and light chains. This interpretation is supported by the Ig quantification data. The remaining IgM well is devoid of an appreciable band. WS, anti-whole serum; G, anti-canine IgG (heavy plus light chain); A, anti-canine IgA (heavy chain); M, anti-canine IgM (heavy chain). (C) PCR for antigen receptor rearrangement performed on blood and bone marrow from the Golden Retriever. A clonal Ig gene rearrangement in bone marrow and blood is shown. Lanes 1 and 4, positive control for DNA; lanes 2 and 5, Ig primers indicating the presence of a single discrete PCR product in blood and bone marrow, respectively, consistent with a monoclonal population of B-cells; lanes 3 and 6, T-cell receptor gamma primers, showing multiple different PCR products, consistent with a polyclonal population of T-cells. hypomagnesemia (1.8 mg/dL, RI 1.9–2.7 mg/dL), and presumptive diagnosis was B-cell lymphoma. Determi- mildly increased total CO2 concentration (28 mmol/L, nation of immunophenotype by flow cytometric anal- RI 16–25 mmol/L). Total protein (7.0 g/dL, RI 5.3–7.2 g/dL) ysis or PCR for antigen receptor rearrangement (PARR) and globulin (3.1 g/dL, RI 2.0–3.8 g/dL) concentrations was recommended. Fine-needle aspirates of the popli- were within reference intervals. Urinalysis performed teal lymph nodes were nondiagnostic, containing only on urine obtained by cystocentesis demonstrated iso- mature adipocytes and blood. Based on the plasma- sthenuria (specific gravity 1.008) with rare RBC, WBC, cytoid features of the atypical cells, multiple myeloma and granular casts. Proteinuria was not detected using (MM) was also a differential diagnosis, and survey a standard reagent strip (Multistix, Bayer Corp., Elk- skeletal radiographs and evaluation of serum for hart, IN, USA) or with sulfosalicylic acid precipitation. monoclonal gammopathy were also recommended. The dog was admitted to CSU-VTH and intra- Skeletal survey radiographs and flow cytometric venous 0.9% NaCl was administered overnight. The analysis were not performed, but consent was given following morning the ionized calcium concentration for PARR and evaluation of serum for a monoclonal was unchanged. Parathyroid hormone-related peptide gammopathy. Serum was submitted for immunoglob- (PTHrP) concentration in plasma sent to the Michigan ulin (Ig) quantification and immunofixation electro- State University Diagnostic Center was 0 pmol/L phoresis. Ig quantification (Kent Laboratories, (RI, 0–1.0 pmol/L). Bellingham, WA, USA) revealed a marked increase Cytologic evaluation of a bone marrow aspirate in IgA concentration (1035 mg/dL, RI 40–60 mg/dL) collected from the proximal aspect of the right femur concurrent with moderately decreased concentrations revealed highly cellular spicules with orderly matura- of IgG (414 mg/dL, RI 1000–2000 mg/dL) and IgM tion of erythroid and myeloid cells. In addition, atyp- (40 mg/dL, RI 100–200 mg/dL). Immunofixation elec- ical large mononuclear cells accounted for 43% of all trophoresis (HYDRASYS Agarose Gel Electrophoresis nucleated cells (Figure 1A). These cells exhibited large System, Sebia Inc., Norcross, GA, USA; anti-Ig anti- nuclei that were ovoid to round to irregularly shaped bodies, Bethyl Laboratories Inc., Montgomery, TX, with finely stippled chromatin and variable numbers USA) revealed a dense and discrete single band within of large nucleoli. The cells had scant to moderate the IgA lane, indicative of an IgA monoclonal protein amounts of deeply basophilic cytoplasm. Occasional (M-protein) (Figure 1B). The PARR assay was per- cells displayed prominent paranuclear clear zones, ec- formed at CSU on both blood and bone marrow in centrically located nuclei with condensed chromatin, order to increase the likelihood of detecting neoplastic or bi- and trinucleation, with marked anisokaryosis cells. Analysis revealed a clonal B-cell population in and anisocytosis. Based upon cytomorphologic fea- both blood and bone marrow (Figure 1C) even though tures, the neoplastic cells were tentatively identified abnormal lymphocytes were not detected in the CBC. as lymphocytes with plasmacytoid features and the Based upon these findings, the final diagnosis was 448 Vet Clin Pathol 39/4 (2010) 447–453 c 2010 American Society for Veterinary Clinical Pathology Seelig et al IgA secretory neoplasms in 2 dogs secretory IgA B-cell lymphoma, although MM was evaluation of a nasal adenocarcinoma diagnosed 3 considered a possibility. months previously by histopathologic evaluation, The dog was initially treated with intravenous epistaxis, and severe anemia. On presentation, the dexamethasone sodium phosphate (0.2 mg/kg), sub- dog was quiet and alert with normal body temperature