Waldenström's Macroglobulinemia in a Normoproteinemic Dog with Atypical Bimorphic Plasmacytoid Differentiation and Monoclonal Gammopathy

A 2-year-old neutered female Small Munsterlander dog was presented for an insect bite. Physical examination revealed a poor body condition, a peripheral lymphadenomegaly, and suspected splenomegaly. A complete blood count (Sysmex XN-V) revealed marked leukocytosis with lymphocytosis and abnormal dot plots. An abnormal monomorphic lymphoid population and marked rouleaux formation were noted on the blood smear. Lymph node aspirates contained an atypical bimorphic population of lymphocytes, either with a plasmacytoid or a blastic appearance. This double population was also found in the spleen, liver, bone marrow, tonsils, and other tissues. Peripheral blood and lymph node clonality assays revealed clonal BCR gene rearrangement. Flow cytometry revealed a mixed population of small-sized B-cells (CD79a+ CD21+ MHCII+) and medium-sized B-cells (CD79a+ CD21- MHCII-) in lymph nodes and a dominant population of small-sized mature B-cells (CD21+ MHCII+) in peripheral blood. Though normoproteinemic, serum protein electrophoresis revealed an increased α2-globulin fraction with an atypical restricted peak, identified as monoclonal IgM by immunofixation. Urine protein immunofixation revealed a Bence-Jones proteinuria. A diagnosis of Waldenström's macroglobulinemia was made. Chemotherapy was initiated, but the dog was euthanized 12 months after the initial presentation due to marked clinical degradation.

Clinical characteristics and outcomes of Mott cell lymphoma in nine miniature dachshunds

BACKGROUND

Lymphoma with Mott cell change, or Mott cell lymphoma (MCL), is an uncommon variant of canine lymphoma. Because of its rare occurrence, there has been no comprehensive study describing the disease so far. Miniature dachshunds, a popular breed in Japan, sometimes experience MCL.

OBJECTIVES

To investigate the clinical characteristics and outcomes of MCL in miniature dachshunds.

METHODS

Medical records were retrospectively reviewed to identify miniature dachshunds diagnosed with MCL and other types of lymphoma. Data on clinical and laboratory findings, treatments and outcomes were collected. Survival times were compared between miniature dachshunds with MCL and other types of lymphoma.

RESULTS

Of the 87 miniature dachshunds diagnosed with lymphoma, 9 (10%) had cytological characteristics of MCL. All 9 miniature dachshunds with MCL were categorised as having alimentary lymphoma (small and/or large intestine, 6 dogs; mesenteric lymph node, 3 dogs). The median age was 3.1 years (range, 2.0-9.4 years). All nine dogs were treated with chemotherapeutic protocols used for large cell lymphoma or alkylating agents such as melphalan or chlorambucil. The overall response rate to initial chemotherapy was 78%, and the median progression-free survival was 105 days. Overall survival in these nine dogs ranged from 6 to >1513 days (median, 240 days), which was significantly longer than in 29 miniature dachshunds with alimentary large cell lymphoma other than MCL (median, 57 days; p = 0.0491).

CONCLUSIONS

MCL in miniature dachshunds can be recognised as a peculiar type of B-cell lymphoma occurring in relatively young dogs as an alimentary form and has a longer survival compared with typical alimentary large cell lymphoma.

Case report: Suspected plasmablastic lymphoma in a dog resembling the clinical presentation in humans

Plasmablastic lymphoma (PBL) is a rare form of lymphoma in people. PBL originates from plasmablasts and usually presents with swelling/mass in the mouth/neck. A 7-year-old Mongrel dog was presented for a large oral and neck mass. Cytology and histopathology were suggestive of a round cell tumor that was suspected to be lymphoma. An immunohistochemical (IHC) stain panel showed positive for CD18, thus supporting the diagnosis of round cell tumor, but negative for T- and B-cell lymphomas, CD3, CD20, and PAX-5. Other markers including cytokeratin AE1/3 (for epithelial cell origin), CD31 (for endothelial cells), SOX10 (for melanoma), IBa-1 (for histiocytic sarcoma), and CD117 (for mast cell tumor) were all negative. MUM-1 (for plasma cell differentiation) was strongly positive and CD79a (B cell and plasma cells) was also scantly positive. Based on the histopathology and immunohistochemistry results in combination with the clinical presentation, a suspected diagnosis of PBL was made. As per available literature, this is perhaps the first highly suspected case of PBL in a dog.

Mott Cell Differentiation in Canine Multicentric B Cell Lymphoma with Cross-Lineage Rearrangement and Lineage Infidelity in a Dog

Simple Summary

The scientific literature regarding Mott cell differentiation in canine lymphoma is scarce. Mott cells are defective in immunoglobulin secretion and are derived from plasma cells, and lymphoma is a severe condition characterized by the proliferation of neoplastic lymphoid cells. Lymphoma can be divided into B- or T-cell according to their origin. Whether the origin of lymphoma is B- or T-cell can be confirmed by PCR for antigen receptor rearrangement or flow cytometry assay. However, the phenomenon in which B- and T-cells are simultaneously identified in PCR for antigen receptor rearrangement and flow cytometry is called cross-lineage rearrangement and lineage infidelity, respectively, and is known to be occasionally found in canine lymphoma. These phenomena have not been reported in canine lymphoma with Mott cell differentiation. This study is the first report of Mott cell differentiation in canine B-cell lymphoma with cross-lineage rearrangement and lineage infidelity. This study describes the clinical features, diagnosis, and treatment of this unknown type of cancer in a 4-year-old female mongrel dog.

Abstract

Lymphoma is a severe condition characterized by the proliferation of neoplastic lymphoid cells. A 4-year-old female mongrel dog presented with solitary lymph node enlargement. Significant right prescapular lymphadenopathy and abdominal enlargement were observed during physical examination. A complete blood count revealed lymphocytosis, and a peripheral blood smear revealed lymphoblastosis and Mott cells. Fine needle aspiration cytology (FNAC) of the right prescapular lymph node revealed a predominant population of lymphoblasts and Mott cells. Based on the FNAC and blood smear results, the patient was diagnosed with leukemic state multicentric B-cell lymphoma with Mott cell differentiation. Subsequent PCR for antigen receptor rearrangement and flow cytometry revealed that the patient exhibited cross-lineage rearrangement (CLRA) and lineage infidelity (LI), respectively. CHOP-based chemotherapy was initiated, however, the patient’s disease was progressive. The patient died three months after the initial presentation. Mott cell differentiation in canine B-cell lymphoma (MCL) has rarely been reported in the veterinary literature and seems to show an unusual clinical course. To the best of our knowledge, no reports of MCL with CLRA and LI exist. We report the clinical features, diagnosis, and treatment of MCL with CLRA and LI.

Lymphoma in Miniature Dachshunds: A retrospective multicenter study of 108 cases (2006-2018) in Japan

Background

Miniature Dachshunds (MD) are predisposed to lymphoma with disease onset of young age and long‐term survival.

Objectives

To compare clinical features and survival time of lymphoma in MD and non‐MD.

Animals

One hundred and eight MDs with lymphoma and 149 non‐MD breed dogs with lymphoma were included in the study.

Methods

This was a retrospective multicenter observational study. Lymphoma was classified based on signalment, histopathology/cytology, and anatomical site of the disease. For each type of lymphoma, median survival time was analyzed by Kaplan‐Meier estimates and life table analysis. Prognostic factors for large‐cell gastrointestinal lymphoma (LGIL) were analyzed using Cox regression.

Results

Gastrointestinal lymphomas were more common in MDs (53/108) compared to non‐MDs (41/149). The multicentric lymphoma was most common in non‐MD breed dogs (74/149) compared to MDs (33/108). The median age that dog developed lymphoma in MD and non‐MD were both 10 years old; however, lymphomas were more frequently observed in younger dogs (<4 years) in MDs (20/108) compared to non‐MDs (9/149; P = .002). Seventy percent were diagnosed with B‐cell with median age of diagnosis was 3 (1‐14) years. Mott cell differentiation was observed in 6 dogs. Age <4 years and B‐cell phenotype were significant factors for longer survival time in MD with LGIL.

Conclusions and Clinical Importance

Lymphomas in MDs involved gastrointestinal lesions at higher frequency compared to other dog breeds examined. B‐cell lymphoma was more common in early‐onset LGIL in MD and cases that involved Mott cell differentiation were observed. Awareness of this specific presentation of lymphoma in dogs will possibly affect the treatment decision process for the owners of MD with LGIL.

Non Epitheliotropic B-Cell Lymphoma with Plasmablastic Differentiation vs. Cutaneous Plasmacytosis in a 12-Years-Old Beagle: Case Presentation and Clinical Review

Cutaneous lymphoid neoplasms and cutaneous plasmacytosis are rare in the dog; in human and in veterinary medicine, these have many clinical, cytological, histological, and phenotypic similarities, and a diagnosis of certainty is not easy. The aim of this study is to describe a case of cutaneous non epitheliotropic B-cell lymphoma (CNEBL) with plasmablastic differentiation vs. multiple cutaneous plasmacytosis (CP) in a dog, since the scarce bibliographic data on these topics. A 12-year-old male Beagle dog was presented for multiple, nodular, cutaneous, and subcutaneous, indolent masses disseminated on the whole body. Cytological, histological, flow cytometric, and immunohistochemical examinations, as well as complete radiographic evaluation, echocardiography, and abdominal ultrasound were performed. Cytology, histopathology, flow cytometric, and immunohistochemical examination, performed on the skin lesions, revealed a B-cell phenotype with plasmablastic differentiation. Nevertheless, a final diagnosis could not be achieved and it was categorized as a case of borderline CNEBL with plasmablastic differentiation versus CP. The dog was treated with a COP chemotherapeutic protocol. Total remission was obtained and relapse occurred 120 days later. To our knowledge, specific markers are actually unavailable to certainly differentiate CNEBL and CP in the dog and future studies are needed to improve knowledge on these pathologies in veterinary medicine, since prognosis and therapy are different.

Hypoglobulinemia in a dog with disseminated plasma cell neoplasia: Case report and review of the diagnostic criteria

This is the first reported case of hypoglobulinemia in a dog with disseminated plasma cell neoplasia. A 6-year-old male intact Rottweiler was referred to the U-Vet Animal Hospital (Werribee, Vic, Australia) for weight loss, hyporexia, lethargy, vomiting, and soft stools. Examination of a buffy coat preparation and splenic and liver aspirates revealed a monomorphic population of plasmacytoid cells, and the same cells comprised approximately 90% of bone marrow samples submitted for cytologic and histologic evaluation. Biochemistry revealed a hypoglobulinemia, and the presence of an M-protein was not supported by serum and urine protein electrophoresis or serum immunofixation. Immunohistochemistry demonstrated strong nuclear labeling for MUM-1.

Lymphoma with Mott cell differentiation and validation of immunohistochemical lymphoid markers in an African pygmy hedgehog (Atelerix albiventris)

A 2-year-old female intact African pygmy hedgehog was presented for diagnostic investigation of a 2-month reduction in appetite, with weight loss and recent vomiting. Clinical examination revealed a large, firm mass originating from the left cranial abdomen. Ultrasound-guided fine-needle aspirates of the mass, liver, and mesenteric lymph nodes revealed a population of pleomorphic round cells, some of which contained variable numbers of round, clear vacuoles, consistent with a diagnosis of lymphoma with Mott cell differentiation. At postmortem examination, there was marked diffuse splenic enlargement, with infiltration by a soft tissue mass. There were multiple coalescing liver masses, kidney pallor, and mesenteric lymph node enlargements. On histologic examination, the spleen, lymph nodes, and masses in the liver were extensively infiltrated by proliferating lymphoid cells that had plasmacytoid and Mott cell differentiation. Cells with Mott cell morphology had an accumulation of periodic acid-Schiff-positive material in cytoplasmic inclusions and were positive for cytoplasmic nucleic acids when stained with methyl green pyronin. In the population of neoplastic lymphoid cells, a majority of cells expressed the transcription factor Pax5, which drives B-cell differentiation, and a minority expressed transcription factor IRF4/MUM-1, which drives plasma cell differentiation, indicating B-cell lymphoma with plasmacytoid differentiation.

Canine Cutaneous Plasmacytosis: 21 Cases (2005-2015)

BACKGROUND

Cutaneous plasmacytosis (CP) is a syndrome of multiple cutaneous plasma cell tumors, in the absence of multiple myeloma. Although rare in both humans and dogs, treatment recommendations are usually extrapolated from multiple myeloma protocols. To date, no case series of CP have been described in the veterinary literature.

HYPOTHESIS/OBJECTIVES

To describe clinical presentation, determine treatment response rates and duration, and report overall survival of dogs with CP.

ANIMALS

Twenty-one client-owned dogs with CP.

METHODS

Medical records of 21 dogs with CP were reviewed. Diagnosis was based on histopathologic evaluation of at least 1 representative cutaneous or subcutaneous lesion in dogs with ≥3 lesions. Dogs with suspicion of multiple myeloma were excluded.

RESULTS

The most commonly affected breeds were the golden (5/21) and Labrador retriever (3/21). Fourteen of 21 dogs had >10 lesions, with some having >100. Lesions commonly were described as round, raised, pink-to-red, and variably alopecic or ulcerated. The most commonly used drug protocol was combined melphalan and prednisone, with an overall response rate (ORR) of 73.7% (14/19 dogs). Single-agent lomustine was associated with a similar ORR of 71.4% (5/7 dogs). For all treatments combined, the median progression-free interval after the first treatment was 153 days. The median survival time from the first treatment was 542 days.

CONCLUSIONS AND CLINICAL IMPORTANCE

Alkylating agents were effective in inducing remission of CP; corticosteroids, melphalan, and lomustine were the most commonly used drugs. Survival times were similar to those reported in dogs with multiple myeloma treated with alkylating agents.

Monoclonal hyperglobulinemia in lymphosarcoma in a cockatiel (Nymphicus hollandicus) and a blue and gold macaw (Ara ararauna)

A 15-yr-old cockatiel (Nymphicus hollandicus) presented with decreased activity and appetite. A presumptive diagnosis of lymphoproliferative disease was made because of a monoclonal band observed on plasma protein electrophoresis. The owner declined further diagnostics or treatment, and the bird died 2 yr later. In a second case, a 4-yr-old blue and gold macaw (Ara ararauna) presented with lethargy and anorexia. Despite supportive treatment, the bird died 7 days later. Blood studies also demonstrated a monoclonal band on plasma protein electrophoresis. The histologic review of tissues from both birds found extensive neoplastic lymphoplasmocytic cells in the liver and supported a diagnosis of lymphosarcoma.