Histopathological and immunophenotypical assessment of canine primary splenic lymphoma according to the World Health Organization / Avaliação histopatológica e imunofenotípica segundo a classificação da Organização Mundial da Saúde do linfoma esplênico primário em cães

Although there are several studies addressing multicentric lymphoma in dogs, data regarding splenic lymphoma remains scarce. The diagnosis of splenic lymphoma using the World Health Organization (WHO) classification system can aid prognostic characterization of splenic lymphoma. The aim of this study was to evaluate the most common histological types of splenic lymphoma in dogs from Brazil according to the WHO classification. We assessed 33 cases of splenic lymphoma diagnosed by histopathologic and immunohistochemical (IHC) analysis submitted to VETPAT- Pathology Laboratory, Campinas-SP, Brazil. IHC was performed using antibodies against CD3 for T-cell and CD79α for B-cell identification . Mean age of patients with splenic lymphoma was 9.8 years. The most affected breeds were mixed breed dogs (33%) followed by Pit bulls and Yorkshires (9.0%). The most prevalent histological type was marginal zone B-cell lymphoma (60.7%) followed by diffuse large B-cell lymphoma (12.1%) and lymphoblastic T-cell lymphoma (12.1%). Histological and immunohistochemical characterization of splenic lymphoma is important due to the high prevalence of indolent lymphomas such as marginal zone, which may be less aggressive and thus have different prognostic and distinct forms of treatment when compared to high-grade lymphomas.(AU)

Embora existam diversos estudos a respeito do linfoma multicêntrico em cães, os dados sobre linfoma esplênico primário são escassos. O diagnóstico do linfoma esplênico utilizando a classificação da Organização Mundial da Saúde (OMS) pode melhorar a caracterização da doença. O objetivo do estudo foi avaliar os principais tipos de linfoma esplênico primário em cães no Brasil de acordo com a classificação da OMS. Foram avaliados 33 casos de linfoma esplênico diagnosticados por histopatologia e imuno-histoquímica submetidos ao Laboratório de Patologia Veterinária (VETPAT, Campinas/SP). A imuno-histoquímica foi realizada utilizando os anticorpos CD3 para linfomas T, CD79α para linfomas B. A média de idade dos pacientes com linfoma esplênico foi de 9,8 anos. Os animais sem raça definida (SRD) foram os mais acometidos (33%) seguidos de PitBulls e Yorkshire (9,0%). O tipo histológico mais comum foi o linfoma de zona marginal representando 60,7% dos casos seguido do linfoma difuso de grandes células B (12,1%) e linfoma linfoblástico T (12,1%). A caracterização histopatológica e imuno-histoquímica do linfoma esplênico é importante devido à alta prevalência de linfomas indolentes como o linfoma de zona marginal, que devido ao seu comportamento indolente apresenta prognóstico e tratamento distintos quando comparado aos linfomas de alto grau.(AU)

Platelet satellitism and dual surface immunoglobulin light-chain expression in circulating splenic marginal zone lymphoma cells.

Platelet satellitism is believed to be an in vitro phenomenon induced at room temperature in ethylenediamine tetraacetic acid-anticoagulated blood. Most reports involve neutrophils; involvement with circulating lymphoma cells are exceedingly rare. Normally, mature B cells exhibit allelic exclusion in which a single class of surface immunoglobulin light chains (either κ or λ) is expressed. The simultaneous expression of both κ and λ immunoglobulin light chains is rare. Herein, we report the unusual case of a patient with splenic marginal zone lymphoma in which circulating lymphoma cells express dual surface immunoglobulin light chains and exhibit platelet satellitism. In addition to clinical findings, a comprehensive analysis of the peripheral blood including correlated light and electron microscopy as well as flow cytometry are described.

Indeterminate cell tumor of the spleen.

Indeterminate cell tumor is an extremely rare neoplasm that mainly occurs in the skin. We report a case of indeterminate cell tumor arising from the spleen, a previously unreported site for indeterminate cell tumor. Histologically, the tumor showed nests, nodules, and sheets of large polygonal cells with mostly oval nuclei; open chromatin; variable nucleoli; and abundant, eosinophilic cytoplasm. Some cells possessed irregularly convoluted nuclei with nuclear grooves and granular cytoplasm, suggestive of Langerhans cells. Immunohistochemically, the tumor cells were diffusely positive for S-100 and CD1a and negative for Langerin. No Birbeck granules were found by electron microscopy. Clinical and radiologic examination showed no other organomegaly or lymphadenopathy. A diagnosis of primary indeterminate cell tumor of the spleen was rendered. To the best of our knowledge, this is the first indeterminate cell tumor reported in the spleen. Biologic insights into dendritic cells in the spleen and the pertinent literature on these entities are reviewed.

[Sclerosing angiomatoid nodular transformation of spleen: a clinicopathologic study of 10 cases with review of literature].

OBJECTIVE: To study the clinicopathologic features, differential diagnosis and pathogenesis of sclerosing angiomatoid nodular transformation of spleen. METHODS: Ten cases of sclerosing angiomatoid nodular transformation of spleen were retrieved from the archival file. Histochemical and immunohistochemical (EnVision method) studies were performed. Ultrastructural findings were also available in one of them. RESULTS: Sclerosing angiomatoid nodular transformation was characterized by micronodular appearance of vascular spaces lined by plump endothelial cells with interspersed ovoid spindle cells. Immunohistochemical study showed that the endothelial cells of vessels in the angiomatoid nodules had various expressions of immunologic phenotypes and could be mainly classified into 3 types: CD34(+)/CD31(+)/CD8⁻ endothelial cells of the capillaries, CD8(+)/CD31(+)/CD34⁻ lining cells of the sinusoids and CD31(+)/CD8⁻/CD34⁻ endothelial cells of the small veins. Collagen network and dilated lymphatic sinuses were evident under transmission electron microscope. CONCLUSIONS: Sclerosing angiomatoid nodular transformation of spleen is a rare benign entity. It may represent a reactive condition and bears some relationship with splenic angioma. It needs to be distinguished from borderline or malignant vascular tumors of spleen.

Sonographic features of histiocytic neoplasms in the canine abdomen.

The purpose of this retrospective study was to describe the ultrasonographic features of malignant histiocytosis (MH), malignant fibrous histiocytoma, and histiocytic sarcoma in abdominal organs of dogs. The medical records of 18 dogs that had undergone abdominal sonography and had a histopathologic diagnosis of abdominal MH, malignant fibrous histiocytoma, and histiocytic sarcoma were reviewed. The organ most commonly affected was the spleen. MH was the most common followed by histiocytic sarcoma and malignant fibrous histiocytoma. In the spleen there were often multiple hypoechoic nodules with well-defined borders. In one dog, without focal lesions, the spleen was enlarged and hypoechoic. The liver was the second most commonly affected organ. MH was most common followed by histiocytic sarcomas and malignant fibrous histiocytoma. The most common sonographic feature in the liver was the presence of multiple hypoechoic nodules with well-defined borders. One dog without hepatic nodules had a liver that was ultrasonographically enlarged and hypoechoic. MH in the abdominal lymph nodes resulted in hypoechoic lymphadenopathy. Malignant fibrous histiocytoma was the only neoplastic type in the kidneys appearing as a single heteroechoic renal mass with well-defined borders. MH was observed in the stomach of one dog. Sonographically there was a single well circumscribed hypoechoic mass with well-defined borders and abnormal stomach layers. In this study it was not possible to differentiate between MH, malignant fibrous histiocytoma, and histiocytic sarcoma using sonography.

Signet ring-like light chain myeloma with systemic spread.

The morphological presentation of malignant plasma cells in multiple myeloma (MM) varies from mature to anaplastic plasma cells with only one reported case of signet ring variant. We describe here another case of signet ring-like lambda light chain MM associated with extra-skeletal spread to lymph nodes, spleen and liver. The clinical and pathological presentations were atypical with no evidence of bone-lytic lesions or monoclonal component on protein electrophoresis, leading to a delay of several years in the diagnosis. Recognition of this morphological entity of MM may help in an early diagnosis of this rare variant.

Interdigitating dendritic cell sarcoma of the spleen: report of a case with a review of the literature.

Interdigitating dendritic cell sarcoma is an extremely rare neoplasm that mainly occurs in the lymph nodes. We report a case of interdigitating dendritic cell sarcoma arising from the spleen, a previously unreported site for interdigitating dendritic cell sarcoma. An 87-year-old woman, visiting Ashigara Hospital with complaints of palpitation and dyspnea, was found to have pancytopenia and low proteinemia. Abdominal ultrasonography and CT scanning demonstrated severe splenomegaly with heterogeneous enhancement. She received a splenectomy under the clinical diagnosis of a splenic tumor. Grossly, the spleen was markedly enlarged, with confluent massive nodules. Microscopically, the normal architecture was effaced with diffuse proliferation of large pleomorphic cells arrayed in a somewhat sheet-like pattern. Erythrophagocytosis was commonly observed. Immunohistochemical studies showed that the tumor cells were positive for S-100 protein, fascin, vimentin, and CD68, but uniformly negative for CD45, B- and T-cell markers, CD1a, CD30, complement receptors, CD34, Factor VIII, HMB-45, and lysozyme. Ultrastructurally, the tumor cells possessed complex interdigitating cytoplasmic dendritic processes. Birbeck granules were absent. Based on these findings, the present case was diagnosed as interdigitating dendritic cell sarcoma. The patient died of multiple liver metastases 3 months postoperatively.

Pleomorphic large cell sarcoma of the spleen with rhabdomyosarcomatous differentiation.

An unusual case is reported of pleomorphic large cell sarcoma of the spleen with rhabdomyosarcomatous differentiation in a 34-year old male. According to our knowledge, such a neoplasm has never been reported in the literature.

Pathologic and prognostic characteristics of splenomegaly in dogs due to fibrohistiocytic nodules: 98 cases.

Ninety-eight canine splenectomy specimens consisting of combined nodular lymphoid and fibrohistiocytic cell proliferation were evaluated for seven light microscopic characteristics. Electron microscopic features in eight primary and two metastatic nodules (liver) were also evaluated. Nodular fibrohistiocytic proliferation in the canine spleen is characterized by a mixed population of histiocytoid and/or spindle cells in varying proportions intermixed with hematopoietic elements, plasma cells, and/or lymphocytes. These nodules seem to form a continuum between splenic lymphoid nodular hyperplasia and malignant splenic stromal neoplasms (malignant fibrous histiocytoma). Immunohistochemical methods used on 32/98 specimens showed uniform and strong positive staining among fibrohisiocytic cells for vimentin and desmin; S100 protein was similarly stained in general abundance. Individual cells strongly stained with smooth muscle actin were sparse but widely distributed. Proliferating cell nuclear antigen was not useful in the subjective differentiation of nodules taken from dogs that died of spleen-related causes and those surviving 12 months following splenectomy. A spectrum of cell types were observed by electron microscopy within each nodule. Fibroblasts, macrophages, intermediate fibrohistiocytic types, and several forms of splenic reticular cells were present. There were no consistent alterations in hematology or serum chemistry profiles of these dogs to provide useful diagnostic/prognostic information. Among the 93/98 dogs with complete (12 month) follow-up information, 48% (45/93) were alive and 52% (48/93) were dead. Dogs that died or were euthanatized during the follow-up period had a median survival of 5 and 5.5 months, respectively (range 0-15 months). Forty-four percent (21/48) died from causes linked to their splenic disease, and 35% (17/48) died from competing causes. The cause of death in 21% (10/48) was unknown. Lymphoid:fibrohistiocytic proportion and mitotic index in the nodules were anatomic features most predictive of postplenectomy mortality. A higher proportion of lymphoid to fibrohistiocytic type cells was associated with increased long-term survival, whereas lower lymphoid:fibrohistiocytic proportions and higher mitotic index indicated a probability of higher short-term mortality.

Splenic lymphoma with villous lymphocytes showing del(7) and inv(10).

A 49-year-old woman presented with splenic lymphoma with villous lymphocytes (SLVL) that showed a clonal abnormality of del(7)(q22q32) in addition to inv(10)(p13q23), the latter being a previously undescribed abnormality in chronic lymphoproliferative disorders. A review of the literature on cytogenetic abnormalities of SLVL indicates that del(7q) is strongly associated with SLVL and may be important in the pathogenesis of this disorder.

Hepatosplenic gammadelta T-cell lymphoma: ultrastructural, immunophenotypic, and functional evidence for cytotoxic T lymphocyte differentiation.

Hepatosplenic gammadelta T cell lymphoma (TCL) is a rare, aggressive subset of peripheral TCL that presents with hepatosplenomegaly and cytopenias. Detailed clinicopathological, ultrastructural, and cytogenetic analyses of these lymphomas are limited; functional characteristics of these lymphomas are unknown. We have undertaken a clinicopathological, immunophenotypic, ultrastructural, cytogenetic, and functional analysis of three hepatosplenic gammadelta TCLs. All patients presented with massive hepatosplenomegaly and anemia, thrombocytopenia, or severe neutropenia; terminal blastlike transformation occurred in one patient. Combination chemotherapy had no response in two patients, but induced complete remission in one. gammadelta T cell receptor (TCR) expression and clonal TCRdelta gene rearrangements were documented in each case. Two different subsets of gammadelta TCL were identified based on delta chain variable region usage; two lymphomas were Vdelta1+, whereas the third was negative for both Vdelta1 and Vdelta2. Cytogenetic analysis was performed on two lymphomas; isochromosome 7q and probable trisomy 8 was shown in one of the Vdelta1+ lymphomas, whereas the Vdelta1 negative lymphoma had 14p+ with t(1;14)(q21;p13). NK cell-associated antigens (CD11c, CD16, or CD56) and cytotoxic T lymphocyte (CTL) effector proteins (perforin, granzyme B, TIA-1, and Fas ligand) were expressed by each lymphoma; dense core cytolytic granules were observed by electron microscopy in both lymphomas studied. Functional studies performed in two cases showed TCR-mediated cytolysis of P815 x 2 FcR+ cells induced by anti-CD3 in a redirected cytolysis assay in one of the CD56+, Vdelta1+ lymphomas, whereas IFNgamma secretion was induced by anti-CD3 in the CD56-, Vdelta1 negative lymphoma. These studies show that hepatosplenic gammadelta TCLs have CTL differentiation, retain functional activity in vitro, and are derived from at least two gammadelta T cell subsets.

An unusual case of a splenic gamma/delta T-cell lymphoma with angiocentric tendency and haemophagocytic syndrome.

We report here an unusual post-thymic T-cell neoplasia of the spleen associated with a rapidly progressive haemophagocytic syndrome. The lymphoma was classified as a medium- to large sized pleomorphic T-cell lymphoma with angiocentric tendency (CD3+, CD43+, CD45RO+ CD45+). Clonality was confirmed by PCR and revealed rearrangement of the T-cell receptor gamma chain. Serological tests excluded a recent EBV infection and in situ hybridization with the EBER probe was negative. Haemophagocytic syndrome was the initial finding in an otherwise symptomless patient and this deteriorated with progression of the T-cell malignancy. Both, the T-cell lymphoma and the haemophagocytic syndrome remained unaffected by chemotherapy. Splenic gamma/delta T-cell lymphoma associated with haemophagocytosis is an uncommon entity which has until now not been widely recognized.

Splenic marginal zone lymphoma. A distinct B-cell neoplasm.

The splenic marginal zone is a morphologically and perhaps immunologically distinct B-cell compartment. Lymphomas arising from cells of the splenic marginal zone are rare. Here we describe the morphologic, immunologic, and clinical features of 14 cases. Patient age ranged from 35 to 79 years (median, 68 years) with a male-to-female ratio of 1:1.8. The spleen was uniformly enlarged (median, 1,540 g; range, 388-3,845 g) in all patients, the neoplastic infiltrate had a nodular pattern in three cases, nodular and diffuse in seven cases, and diffuse in four cases. The neoplastic cells had small to medium-sized nuclei with round, oval, or slightly indented contours, small eosinophilic nucleoli, and a moderate amount of pale cytoplasm. Extrasplenic involvement was present in 12 patients. Lymph nodes often had a vaguely nodular pattern and preservation of sinuses; bone marrow was infiltrated focally (seven cases) or diffusely (one case). Five patients had hepatic involvement. Ultrastructurally, neoplastic cells differed from other small B cells and resembled normal marginal zone cells by having long, serpentine rough endoplasmic reticulum profiles. All lymphomas marked as B cells and light chain restriction was demonstrated in 12 cases. Bcl-2 protein expression was present in all cases. Most cases (70%) were negative for DBA.44 (CD72). Plasmacytic differentiation was present in three cases. In conclusion, splenic marginal zone lymphoma is a B-cell neoplasm with distinctive clinical, morphologic, immunologic, and ultrastructural characteristics.

Ultrastructural investigation of circulating villous lymphoid cells: a tool in the differential diagnosis of splenic lymphoma with villous lymphocytes.

Ultrastructural examination of circulating lymphoid cells was performed in three cases of splenic lymphoma with circulating lymphocytes (SLVL) in order to define morphological features helpful to distinguish this lymphoma from hairy cell leukemia (HCL). The samples for ultrastructural investigation were obtained by Ficoll sedimentation from peripheral blood and routinely processed for electron microscopy. The ultrastructural features examined were: morphology of villi, morphology of nuclei, presence of nucleoli, distribution of heterochromatin, type of cytoplasmic organelles, presence of specific intracytoplasmic structures such as the ribosome-lamella complex, lysosome-like bodies and perinuclear microfibrils. Our results and a careful review of the literature seemed to confirm that SLVL has electron microscopic features typical enough to be relevant in the differential diagnosis with HCL.

Littoral cell angiosarcoma of the spleen. Case report with immunohistochemical and ultrastructural analysis.

This report describes a case of a malignant vascular tumor of the spleen with the morphologic, immunologic, and ultrastructural features observed in splenic sinus-lining cells (littoral cells). Histological examination showed a well-differentiated neoplasm forming ectatic blood channels with intraluminal papillary fronds. Tumor cells displayed malignant nuclear features and hemophagocytosis. Solid neoplastic areas with mitotic figures were present. Ultrastructurally, the tumor cells showed the concomitant presence of lysosomes and Weibel-Palade bodies. Immunohistochemically, the tumor cells were positive for both endothelial (Factor VIII-AG, CD34) and histiocytic markers (cathepsin D, lysozyme, alpha-1-antichimotrypsin). Our results indicate that angiosarcoma may originate from all the vascular compartments of the spleen, including red-pulp sinuses, and may have morphologic and immunophenotypic similarities to littoral cell angioma, a recently described benign vascular tumor of the spleen.

Dual rearrangement of immunoglobulin and T-cell receptor genes in a case of splenic lymphoma with villous lymphocytes.

We report here a case of "splenic lymphoma with villous lymphocytes" (SLVL) which exhibited both B- and T-cell phenotypes and genotypes. The patient was a 73-year-old man. Physical examination revealed splenomegaly and lymphadenopathy. The white blood cell count was 55.2 x 10(9)/L with 70.5% atypical lymphocytes, having cytoplasmic villi, characteristic of SLVL. The atypical cells infiltrated both the red and white pulps. Immunological analysis of the peripheral leukocytes showed both B- and T-cell phenotypes (CD5,CD11c,CD19,CD20,HLA-DR, SmIgM and lambda positive). DNA analysis revealed a dual rearrangement of the immunoglobulin heavy chain gene and T-cell receptor beta gene. SLVL has been identified as a B-cell leukemia with a relatively benign clinical course. This case had both B- and T-cell pheno- and genotypes with a progressive course. To the best of our knowledge, no case of SLVL with dual genotypes has ever been reported.

Hepatosplenic gamma delta T-cell lymphoma. A distinctive aggressive lymphoma type.

The T-cell receptor (TCR) expressed on the surface of most T-lymphocytes is of alpha beta type, and only a minority bear the gamma delta-TCR. Similarly, postthymic T-cell lymphomas rarely express gamma delta-TCR. Hepatosplenic gamma delta T-cell lymphoma is an uncommon entity that has so far not been widely recognized. We report one such case that has been comprehensively studied by multiple modalities and showed the unique occurrence of leukemic picture at presentation. The 39-year-old man presented with fever, marked weight loss, and massive splenomegaly. Peripheral blood showed thrombocytopenia and a white cell count of 5.8 x 10(9)/l, with 66% medium-sized lymphoid cells that had a round or folded nucleus, condensed chromatin and a moderate amount of pale blue cytoplasm. Splenectomy was performed and histologic examination of the spleen, bone marrow, liver, and abdominal lymph nodes demonstrated lymphoma infiltration with a predominantly sinusoidal pattern. Immunohistochemical studies of the lymphoma cells showed a T-cell phenotype: CD2+ CD3+ CD5+ CD7+ gamma delta-TCR+ alpha beta-TCR- CD56+ CD4- CD8- CD16- CD57-. Cytogenetic studies showed complex clonal chromosomal abnormalities of 44,X, -Y, -11, -22, + mar in 3/16 cells. Rearrangement of the TCR gamma chain gene was demonstrated by polymerase chain reaction; the TCR beta chain gene was partially chain reaction; the TCR beta chain gene was partially rearranged. The patient did not respond to single agent chemotherapy, but achieved clinical remission with combination chemotherapy. Based on the available data in the literature, hepatosplenic gamma delta T-cell lymphoma exhibits distinctive clinicopathologic features, and probably represents the neoplastic counterpart of splenic gamma delta T-lymphocytes. This disease is associated with a poor prognosis and usually relapses despite initial response to chemotherapy.

Littoral cell angioma of the spleen. A case report with ultrastructural and immunohistochemical observations.

We describe histological, immunohistochemical and ultrastructural findings in a case of littoral cell angioma of the spleen in a 44 year old man. Beside phagocytosis and heavy haemosiderin deposits in the cytoplasm, a very characteristic and hitherto undescribed feature of the littoral cells was focal accumulations of eosinophilic globules 0.5-2 microns in size, which often entirely filled the cytoplasm of the tumour cells. Ultrastructurally the globules were composed of abundant cytoplasmic deposits of lysosomes and residual bodies. The globules most probably originate from the phagocytized red blood cells, lymphocytes and plasma cells. Immunohistochemically the tumour cells reacted positively with antibodies against factor VIII-related antigen, KiM1P, KP1 and lysozyme and negatively with antibodies against cytokeratins AE1-AE3, EMA and S-100 protein. Ultrastructurally the tumour cells often formed long cytoplasmic processes without external lamina and pinocytic vesicles. Scarce and poorly formed junctions between the tumour cells were seen. Very rarely cytoplasmic rod-shaped microtubulated bodies, often difficult to distinguish from heavy accumulations of lysosomes were observed.