Search

A 12-year-old castrated male Jack Russell Terrier presented with intermittent vomiting. Abdominal ultrasonographic examination detected a thickened stomach wall with a mass measuring approximately 1.5 cm in diameter. Computed tomography revealed a solitary mass measuring approximately 2.1 cm in diameter between the submucosa and muscle layers in the greater curvature the pyloric region of the stomach, and a swelling in the hepatic lymph node. The gastric mass was composed of round neoplastic cells arranged in a diffuse pattern. The neoplastic cells had a round nucleus and a pale abundant cytoplasm. Multinucleated giant cells were often found. Hyalinized eosinophilic material, which did not stain with Congo red and had no affinity for thioflavin T, was also observed. Neoplastic cells were immunopositive for MUM1, CD79a and Ig lambda light chain but negative for CD3, CD20, BLA36, IgG and Ig kappa light chain. Stromal eosinophilic material was positive for Ig lambda light chain. The neoplasm was therefore diagnosed as a gastric plasmacytoma with non-amyloid Ig lambda light chain deposition., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

A 14-year-old domestic longhaired cat presented with a 2-year history of nasal discharge and a recent onset of inappetence and submandibular lymphadenopathy. The cat was humanely destroyed after developing severe respiratory distress. Necropsy examination revealed thickened nasal turbinates and soft palate, and friable red-tan material within the frontal sinus, nasal cavity and nasopharynx. The lungs contained multifocal irregular friable tan nodules. Multiple lymph nodes were enlarged, friable and red-tan in colour. Histopathology revealed a mature type extramedullary plasmacytoma (EMP) within the frontal sinus, nasal cavity, soft palate, larynx, trachea, lungs and multiple lymph nodes. The lymph nodes and larynx also contained marked granulomatous inflammation with extensive intrahistiocytic (and lesser amounts of extracellular) lambda light chain amyloid, confirmed by electron microscopy and immunohistochemistry. Neoplastic cells expressed CD79a and MUM1. This is the first report of an infiltrative EMP of the feline respiratory tract with lymph node metastasis and predominantly intrahistiocytic amyloid., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

A wild, mature, gravid female mule deer (Odocoileus hemionus) was presented with marked neurological signs, including abnormal behaviour, circling and incoordination. The animal was humanely destroyed and submitted for diagnostic investigation. Grossly, a well-demarcated, 3 × 3 × 3 cm intracranial mass replaced the left olfactory bulb and frontal lobe. Histologically, there was a highly cellular, infiltrative and unencapsulated neoplastic mass of round cells with eccentrically located nuclei. Neoplastic cells were immunohistochemically labelled for lambda immunoglobulin light chain. Clusters of CD20- and CD79a-positive cells were scattered throughout the tumour and CD3- and Iba1-positive cells diffusely infiltrated the neoplasm. Ultrastructurally, the cytoplasm of the neoplastic cells had prominent rough endoplasmic reticulum with a variable degree of dilation. Histopathological, immunohistochemical and electron microscopical results were diagnostic for a solitary extramedullary plasmacytoma. Intracranial neoplasms are rarely diagnosed in wildlife species, but they should be included in the differential diagnosis for potential causes of central nervous system disease., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Intestinal extramedullary plasmacytomas (EMPs) are rare tumours in dogs. Three cases of canine intestinal EMP with amyloid deposits are described in this report. These tumours, which were located in the rectal submucosa, had variable numbers of well-differentiated plasma cells and fewer multinucleated giant cells of plasmacytoid and histiocytic morphology, admixed with abundant amyloid. Two cases had metaplastic cartilage and bone within the amyloid deposits. Immunohistochemically, the plasma cells of all three tumours reacted for lambda-light chains of immunoglobulins but not for kappa-chains, indicating monoclonality. Plasma cells of two tumours were also positive to CD79a antiserum. Amyloid deposits were labelled with an A lambda (amyloid of immunoglobulin lambda-light chain origin) antiserum but not with antisera against its precursor protein, the immunoglobulin lambda-light chains, indicating possible conformational changes of amyloidogenic proteins during their transformation into amyloid.

Amyloid deposition in varying amounts and with variable patterns of distribution (focal or diffuse) was demonstrated in eight canine and two feline extramedullary plasmacytomas expressing lambda light chains. Frequently, the neoplastic plasma cells had been displaced by the amyloid deposits. Foreign-body giant cells were regularly detected in the vicinity of the amyloid. In all 10 cases, Congo-red staining of the amyloid was resistant to potassium permanganate oxidation. Immunohistochemically, the amyloid reacted positively with cross-reacting antibodies against human and equine A lambda amyloids. Extramedullary plasmacytomas accompanied by localized AL amyloidosis have so far been described in human beings, dogs, cats and horses.

Clinical, histopathological and immunohistochemical findings are presented from a series of cutaneous lymphoid neoplasms including canine epitheliotrophic lymphoma (n = 7), canine non-epitheliotrophic cutaneous lymphoma (n = 10), canine cutaneous plasmacytoma (n = 10) and feline non-epitheliotrophic cutaneous lymphoma (n = 6). Three cases of canine epitheliotrophic lymphoma expressed the CD3 T-lymphocyte marker, but the remainder were negative for this molecule and for a panel of B-cell markers. Non-epitheliotrophic cutaneous lymphoma was shown to be predominantly of T-cell phenotype (CD3+) in the dog (eight of 10 cases) and cat (five of six cases), the remaining cases in both species being of B-cell origin, expressing the gamma heavy chain of immunoglobulin (with or without lambda light chain). One canine non-epitheliotrophic B-cell lymphoma expressed IgG of the IgG2 subclass. Two of the biopsies from dogs with cutaneous plasmacotyoma were shown to express immunoglobulin alpha chain (one with lambda chain) and two neoplasms were positive for immunoglobulin gamma chain (both with lambda chain). One of the latter immunoglobulins was of the IgG4 subclass. In the majority of all cases of cutaneous lymphoid neoplasia examined, there was a local polyclonal immune response, manifested as infiltration by a mixed population of plasma cells expressing IgG (IgG2, IgG4), IgA or IgM. In the feline tumours CD3+ small T lymphocytes were included in these infiltrates.

Three types of swine immunoglobulin-producing tumours are described. Case 1 was a lymphoplasmacytic lymphosarcoma, in which IgG was intracellularly identified in the plasmacytoid cells. Case 2 was an immunoblastic lymphosarcoma, the large cells of which possessed intracytoplasmic IgG and well developed RER. Case 3 was diagnosed as a plasmacytoma. There were two distinct immunoglobulins, IgG and IgA, in single plasmacytoid cells and the RER was highly developed. The origins of the three cases are discussed according to the theory of B-lymphocyte differentiation sequences and the origins of B-cell lymphomas. The mechanism of "double producers" is discussed with reference to DNA and RNA.

Twenty-three cases of dog plasma cell tumours were investigated for the presence of monoclonal cytoplasmic immunoglobulin light chain types and heavy chain classes. The peroxidase-antiperoxidase method was applied to formalin-fixed, paraffin-embedded tissues, available as stored blocks. Twenty tumours showed a monoclonal light chain type and heavy chain class pattern, two showed a monoclonal light chain type and a biclonal heavy chain class pattern, findings which confirmed the neoplastic nature of the plasma cells. One tumour did not stain with any of the antisera. The results indicate that the method reliably establishes the monoclonality and, consequently, the neoplastic nature of plasma cell proliferations.

Two cases of feline plasmacytoma and nine cases of reactive plasma cell proliferations were examined for the presence of cytoplasmic immunoglobulin light chain types and heavy chain classes, by the peroxidase-anti-peroxidase technique on sections of formalin-fixed, paraffin-embedded tissues. This immunohistochemical technique is an important aid to conventional histological techniques. It helps to differentiate between neoplastic and dense inflammatory plasma cell proliferations by determining the presence of one, or more than one, light chain types in the cells, which corresponds with their neoplastic or reactive nature.

Murine myeloma cells proliferate well in cell culture even after up to 5 years in vitro and the globulin synthesized, as well as the ultrastructure, continues to be comparable to that of original tumor cells. Globulin synthesis by cultured cells from the C3H mouse tumor (x5563) ranged from 6 to 12.2 mg/g/48 hr and by cultured cells from Balb/c mouse plasmacytomas MOPC 21, 31C and 315 up to 40 mg/g/48 hr. This production is greater and occurs over a more prolonged period than those reported in other known published observations on globulin synthesis by normal or neoplastic cells from mice or other sources. However, both rate and quantity of globulin synthesis tend to decrease with time in vitro and this is inversely related to growth rate, which tends to increase with time in vitro. No evidence was found for increased globulin breakdown either intra- or extracellularly in these cultures.