Cutaneous plasmacytoma with Mott cell differentiation in a dog

Cytologic evaluation of aspirate slides from a small, <1-cm, interdigital mass on a 9-y-old, spayed female Yorkshire Terrier revealed a proliferation of discrete, round cells containing few-to-many, variably sized, round, eosinophilic, cytoplasmic inclusions. The top differentials based on the cytologic findings were either a plasma cell tumor or a B-cell lymphoma with Mott cell differentiation. The unencapsulated, well-demarcated, multilobulated round-cell neoplasm was completely excised. Immunohistochemical stains were performed to further characterize the neoplasm, which had immunolabeling for multiple myeloma oncogene 1 and vimentin, but did not react with CD3, CD20, melan A, or ionized calcium-binding adapter molecule 1, nor with a Giemsa special stain. Ultrastructurally, the cytoplasmic granules had Russell body-like morphology. A solitary, cutaneous plasmacytoma with Mott cell differentiation has not been described previously in veterinary medicine, to our knowledge.

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.

Histopathological features and immunophenotyping of canine transmural gastrointestinal lymphoma using full-thickness biopsy samples

To elucidate the histopathological characteristics and immunophenotypes of canine transmural "mass-forming" gastrointestinal lymphomas and plasmacytomas, 83 surgically resected biopsy samples were examined. All lymphomas and plasmacytomas were located in the small or large intestine except for 1 plasmacytoma which was in the stomach. According to the World Health Organization (WHO) classification, B-cell neoplasms (17 cases) included lymphoplasmacytic lymphoma (6/17), plasmacytoma (5/17), follicular lymphoma (3/17), and diffuse large B-cell lymphoma (3/17). Based on nuclear sizes, T-cell neoplasms (66 cases) were broadly divided into large cell lymphoma (LCL; 48/66) and small cell lymphoma (SCL; 18/66). According to the WHO classification, T-cell neoplasms included anaplastic large T-cell lymphoma (ALCL; 10/66), angiotropic T-cell lymphoma (3/66), mixed inflammatory type peripheral T-cell lymphoma (mixed inflammatory type PTCL; 33/66), and PTCL-not otherwise specified (PTCL-NOS; 20/66). Mixed inflammatory type PTCLs were further divided into histiocyte- (27/33) and eosinophil- (6/33) dominant types. Immunohistochemically, lymphoplasmacytic lymphomas were positive for Pax5 (6/6) and IgM (5/6), while plasmacytomas were positive for IgG (5/6) and negative for Pax5. LCLs were immunopositive for granzyme B in 31/48 cases (65%) and CD8 in 9/48 cases (19%), while SCLs were immunopositive for granzyme B in 3/18 cases (17%) and CD8 in 3/18 cases (17%). Furthermore, 8/10 cases (80%) of ALCL and 19/27 cases (70%) of histiocyte-dominant PTCL were immunopositive for granzyme B, whereas 6/20 cases (30%) of PTCL-NOS, 1/6 cases (17%) of eosinophil-dominant PTCL, and no cases of angiotropic T-cell lymphomas were immunopositive for granzyme B. The present study describes the immunophenotypes in different histological types of transmural gastrointestinal lymphomas in the dog.

Intestinal T-cell lymphoma in a coati (Nasua nasua) - Short communication

A 10-year-old female coati (Nasua nasua) was necropsied after an 8-day history of apathy, weight loss and dehydration. Gross changes consisted of multifocal to coalescing nodules ranging from 0.5 to 2.0 cm in diameter in the wall of the small intestine, adjacent to the mesentery and in the mesenteric lymph nodes. Histologically, neoplastic CD3-positive lymphocytes infiltrated all layers of the intestine, as well as the mesenteric adipose tissue and mesenteric lymph nodes. Based on the pathological and immunohistochemical findings, a diagnosis of intestinal T-cell lymphoma was made.

Canine Gastric Pathology: A Review

Gastric disorders are common in dogs and are a major reason for veterinary consultation. In human medicine, the classification of gastric diseases based on histological features, genotypes and molecular phenotypes helps to better understand the characteristics of each subtype, and to improve early diagnosis, prevention and treatment. Canine gastric lesions often show strong histological similarities to their human counterparts. However, such conditions in the canine stomach are poorly studied and their cellular and molecular features are largely unknown. This article reviews the histopathological classification of inflammatory and neoplastic lesions of the canine stomach and provides an update on the application of molecular techniques within the field of canine gastric pathology. The canine disorders are compared with current knowledge of the equivalent human diseases.

Comparison of primer sets for T-cell clonality testing in canine intestinal lymphoma

Clonality testing based on polymerase chain reaction is an important tool for diagnosis of lymphoproliferative diseases. Many primers have been designed and used for canine clonality testing. Canine intestinal lymphoma is usually diagnosed pathologically by examination of excised intestinal or endoscopic biopsy tissues, and clonality testing is sometimes used to support the pathological diagnosis if this examination is inconclusive. In the present study, the sensitivity of each previously published primer set for clonality testing was examined by using formalin-fixed, paraffin-embedded sections from 39 cases pathologically diagnosed as canine intestinal lymphoma (large-cell type). All 39 cases were immunohistochemically positive for cluster of differentiation (CD)3. Thirty-two out of the 39 cases showed clonality in the T-cell receptor gamma (TRG) with at least 1 of the tested primers. The primer set with the highest sensitivity detected all 32 cases with TRG clonality, with a sensitivity of 82.1%. These results provide useful evidence for the selection of primer sets for clonality testing of canine intestinal lymphoma.

Detection of monoclonality in intestinal lymphoma with polymerase chain reaction for antigen receptor gene rearrangement analysis to differentiate from enteritis in dogs

The diagnosis of canine intestinal lymphoma by morphological examination is challenging, especially when endoscopic tissue specimens are used. The utility of detection of antigen receptor gene rearrangement by polymerase chain reaction (PARR) in canine lymphoma has been well established, but its usefulness to distinguish enteritis and intestinal lymphoma remains unclear. In this retrospective study we assessed clonality of 29 primary canine intestinal lymphoma, 14 enteritis and 15 healthy control cases by PARR analysis, using formalin-fixed, paraffin-embedded full-thickness tissue specimens. We could detect monoclonal rearrangements in 22 of 29 canine intestinal lymphomas [76%; 95% confidence interval (CI) 56-90%] and polyclonal rearrangements in all of the enteritis and healthy control cases (100%; CI 88-100%). We revealed a predominance of T-cell phenotype compared to B-cell phenotype (85%; CI 65-96% and 15%; CI 4-35%, respectively). We showed that PARR analysis contributes to differentiation of canine intestinal lymphoma from enteritis and to phenotyping of lymphomas.

Signet ring cell lymphoma with plasmacytic differentiation in a pig

A case of signet ring cell lymphoma in a 3-year-old mixed-breed sow is described. Macroscopical examination revealed enlargement of superficial, thoracic and abdominal lymph nodes and multiple tumor masses in the liver. The neoplastic tissue was composed of follicle center-like structures, in which neoplastic cells with Russell bodies were conspicuous. The bodies were immunostained for IgM (κ), and corresponded to moderately dense amorphous material within markedly distended cisternae of rough endoplasmic reticulum (RER) at the ultrastructural level. In contrast to typical signet ring cell lymphoma, the component cells of which resemble follicular center B lymphocytes with poorly developed RER, most neoplastic cells had features of plasma cells characterized by a cartwheel arrangement of heterochromatin and development of RER. Signet ring cells frequently had one or a few large Russell bodies occupying the entire cytoplasm, which may have been caused by abundant synthesis and defective secretion of immunoglobulin.