Cytologic identification of erythrophagocytic neoplasms in dogs

[Cytologic evidence of hepatocytotropic T-cell-lymphoma in a 15-year-old male cat]

This case report describes the rare phenomenon of emperipolesis-like invasion of lymphatic blasts into the hepatocytes of a 15-year-old European Shorthair cat. The cat presented with nonspecific clinical signs (inappetence and weight loss). Cytologic examination of an ultrasound-guided fine-needle aspirate of the liver showed a subset of hepatocytes with emperipolesis-like invasion by lymphatic blasts. Few extracellularly located lymphatic blasts exhibited erythrophagia. Following the cytological diagnosis of large cell lymphoma and 2 weeks of monotherapy with prednisolone, the patient was euthanized due to his poor general condition. A post-mortem sample was obtained from the liver to confirm the suspected cytological diagnosis of hepatocytotropic lymphoma. Histopathology subsequently confirmed the cytologic findings. Immunohistochemically, the lymphatic blasts were positive for CD3 leading to a diagnosis of hepatocytotropic T-cell-lymphoma, which has rarely been described so far.

A case of infundibular cyst with neutrophil cannibalism by squamous cells in a dog

A 6-years and 6-months-old, neutered male mongrel dog had a skin mass between the left eye and nose. Fine needle aspiration biopsy of the mass revealed giant epithelial cells containing many neutrophils in the cytoplasm. The mass was excised and histopathologically diagnosed as an infundibular cyst with giant epithelial-like cells containing neutrophils in part of the lumen. The giant cells were immunopositive for cytokeratin and immunonegative for vimentin. Cell cannibalism is a cell engulfing phenomenon in which a cell incorporates either the same or a different type of cell and the incorporated cells are degenerate or necrotic. In this case, epithelial cells in the lumen of the cyst incorporated neutrophils, which corresponds to neutrophil cannibalism by squamous epithelial cells.

Erythrophagocytic multiple myeloma in a dog

A 5-y-old spayed female Golden Retriever dog was referred because of severe normocytic normochromic nonregenerative anemia and thrombocytopenia. Serum analysis revealed hyperproteinemia and monoclonal or oligoclonal gammopathy. Fine-needle aspiration of the spleen revealed a highly erythrophagocytic population of neoplastic round cells, morphologically suggestive of plasma cells. After euthanasia, histologic assessment of the spleen and liver revealed an erythrophagocytic round cell tumor. Immunohistochemical analysis of the tumor population was positive for MUM1p and negative for CD3, CD20, and Iba-1, confirming the plasma cell origin of the tumor. Erythrophagocytic multiple myeloma is a very rare neoplastic condition in dogs.

Case report: Haemophagocytic histiocytic sarcoma in an english setter

A 4‐year‐old English setter presented with a 1‐week history of anorexia, lethargy and occasional vomiting. Blood analysis revealed moderate regenerative anaemia, mild monocytosis, thrombocytopaenia, hypoproteinaemia, hypoglobulinaemia, hypocholesterolaemia and increased C‐reactive protein. On ultrasonography, the spleen had multifocal hypoechoic lesions. Fine needle aspirates from the spleen and liver showed marked extramedullary haematopoiesis, an increased number of histiocytes, haemosiderin deposits and erythrophagocytosis. A tentative diagnosis of haemophagocytic histiocytic sarcoma (HHS) was made, and the owners elected euthanasia. On autopsy, the liver and spleen were enlarged. The spleen had an uneven surface and a yellow‐tan spotted appearance. Histologically, the red pulp was highly cellular and dominated by erythroid cells, as well as a population of larger polygonal cells and aggregates of histiocytes. HHS was confirmed by CD11d immunolabelling. This represents the first documented case of HHS in an English setter.

Precursor-targeted immune-mediated anemia in a dog with a stage IV mast cell tumor and bone marrow infiltration

A 12-year-old spayed female Shiba Inu dog was referred to our hospital for a suspected mast cell tumor (MCT) of the bone marrow (BM). Laboratory abnormalities included severe nonregenerative anemia (packed cell volume or PCV: 12.5%; reference interval (RI): 37.3-61.7%; reticulocytes: 35.1 × 10³ /µL; RI: 10-110 × 10³ /µL), and a few mast cells were visualized in the blood smear examination. The BM was hypercellular with hematopoietic cells, a decreased myeloid:erythroid (M:E) ratio (0.77; RI, 0.9-1.8), and no dysplastic hematopoietic cells. Mast cells accounted for 11.5% of the total nucleated BM cells. Neoplastic mast cells and histiocytes phagocytizing erythroid progenitor cells were occasionally noted. The dog was diagnosed with precursor-targeted immune-mediated anemia (PIMA) concurrent and a stage IV MCT infiltrating the BM. Multimodal treatment included toceranib, imatinib, vinblastine, lomustine (CCNU), prednisolone, cyclosporine, mycophenolate mofetil, and a blood transfusion. The dog died due to MCT progression lasting 139 days after the initial BM examination. To the best of our knowledge, this is the first report of a dog presenting with PIMA and a stage IV MCT infiltrating the BM.

Morphological Distinction of Histiocytic Sarcoma from Other Tumor Types in Bernese Mountain Dogs and Flatcoated Retrievers

BACKGROUND/AIM

Histiocytic sarcoma (HS) represents a group of malignant canine tumors to which Bernese Mountain Dogs (BMD) and Flatcoated Retrievers (FCR) are predisposed. The differential diagnosis for HS is broad, encompassing round cell tumors, sarcomas and other histiocytic diseases. The aim of this study was to establish morphological and immunohistochemical criteria for routine use on formalin-fixed, paraffin-embedded samples and cytological smears for the recognition and differentiation of canine HS and its subtypes.

MATERIALS AND METHODS

Retrospectively, tumor sections were reviewed from 449 BMD and 380 FCR with confirmed or suspected HS, other histiocytic conditions, or a disease of the differential diagnosis of HS.

RESULTS

In a large proportion of cases, 47.5% for histology and for 46.3% cytology, the initial diagnosis was changed after the revision process. A large variation in morphological features of HS was observed in this study, making the existence of several subtypes in dogs also very likely. Furthermore, the different percentage of morphological features between BMD and FCR indicates the different mixture of cell type origins resulting possibly from genetic or environmental differences at the onset of HS in those breeds.

CONCLUSION

This study stresses the value of a strictly applied and standardized scoring system for microscopic evaluation of tumor sections and smears, and the implementation of review and revision of pathological diagnoses.

Lymphoma-associated hemophagocytic syndrome in six dogs

Hemophagocytic syndrome (HPS) is a clinicopathological entity characterized by histiocytic proliferation, with marked hemophagocytosis in the reticuloendothelial organs. HPS caused by lymphoma is termed lymphoma-associated hemophagocytic syndrome (LAHS), and there are few reports on canine and feline LAHS. The objective of this study was to examine the clinical, diagnostic, and clinicopathologic features of LAHS in six dogs. The diagnostic criteria of LAHS consisted of lymphoma, bicytopenia or pancytopenia in the blood, and increased hemophagocytosis in the reticuloendothelial organs. In one dog, an ocular form of lymphoma was recognized. A splenic form was recognized in two dogs, and a hepatosplenic form was recognized in three dogs. Immunophenotyping revealed T-cell origin in five dogs and B-cell origin in one dog by polymerase chain reaction for antigen receptor rearrangement analysis. Nonspecific esterase stain was performed to differentiate between neoplastic lymphocytes and hemophagocytes. All five dogs with T-cell lymphoma were diagnosed with large granular lymphocyte (LGL) lymphoma. In three cases, palliative therapy with glucocorticoids was conducted, while the other three cases received chemotherapy as well. The survival times for the three dogs with glucocorticoids only were 6, 6, and 10 days and were 30, 54, and 68 days for the three treated with anticancer therapy. The median survival time for the dogs was 20 days. This report indicates that canine LAHS is likely to be caused by LGL lymphoma, and it has an aggressive behavior and poor general prognosis, as seen in humans.

Cytology of Bone

Cytology of bone is a useful diagnostic tool. Aspiration of lytic or proliferative lesions can assist with the diagnosis of inflammatory or neoplastic processes. Bacterial, fungal, and protozoal organisms can result in significant osteomyelitis, and these organisms can be identified on cytology. Neoplasms of bone including primary bone tumors such as osteosarcoma, chondrosarcoma, fibrosarcoma, synovial cell sarcoma, and histiocytic sarcoma and tumors of bone marrow including plasma cell neoplasia and lymphoma and metastatic neoplasia can result in significant bone lysis or proliferation and can be diagnosed effectively with cytology.