Diffuse leptomeningeal malignant histiocytosis in the brain and spinal cord of a Tibetan Terrier

Diffuse leptomeningeal histiocytic sarcoma in the cerebrospinal fluid of 2 dogs

Two adult male castrated dogs were evaluated for progressive paraparesis and ataxia. Neurologic examination showed severe ataxia, delayed proprioceptive placement in the pelvic limbs, pain upon palpation of the lumbar spine as well as facial paresis in one dog, and decreased withdrawal reflex of the pelvic limbs in the other dog. Magnetic resonance imaging (MRI) in both dogs showed diffuse meningeal and intramedullary lesions. However, no evidence of a mass was found. Biopsies could not be performed safely due to the location of the lesions. Cerebrospinal fluid (CSF) examination revealed an inflammatory pleocytosis associated with increased protein concentration and numerous large atypical round cells, often multinucleated. Nuclear fragmentation, micronuclei, and rare atypical mitoses were observed. Immunocytochemistry revealed CD1(+) and CD11c(+) staining, which, in concert with the morphology confirmed the diagnosis of histiocytic sarcoma (HS). Euthanasia was elected due to poor prognosis. Histopathologic examination showed diffuse spinal and meningeal infiltration with CD18(+) neoplastic cells, without any evidence of mass formation, which completed the diagnosis of diffuse leptomeningeal HS involving the brain and the spinal cord. Canine central nervous system (CNS) HS has been seldom reported in the literature, with only isolated cases identified on CSF cytology. The cases reported here are remarkable in describing a diffuse CNS leptomeningeal HS associated with neoplastic cells in the CSF of dogs without a tumor mass. These cases emphasize the potential critical importance of CSF analysis in providing an antemortem diagnosis of neoplasia in neurologic patients.

Histological and immunohistochemical studies on primary intracranial canine histiocytic sarcomas

Histiocytic sarcoma is a progressive and fatal malignant neoplasm that mainly occurs in middle- to old-aged dogs. This study describes clinicopathological, histological and immunohistochemical characteristics of intracranial histiocytic sarcomas in 23 dogs. Magnetic resonance imaging and/or computed tomography of the brains revealed that the tumors mainly located in the cerebrum, particularly the frontal lobe. Seizure was a predominant clinical sign in most of the cases. Histologically, the tumor cells were morphologically classified into round/polygonal- and spindle-shaped cell types. There was a significant association between tumor cell types and hemophagocytic activity (P<0.05). However, there was no significant difference in other clinicopathological parameters and mitotic index between the 2 types. Immunohistochemically, tumor cells were strongly positive for HLA-DR, Iba-1 and CD204 in all the 23 cases, for iNOS in 20, for CD163 in 17, for CD208 (DC-LAMP) in 9, for lysozyme in 8 and for S100 in 5 cases. In addition, the Ki67-proliferative index showed range of 0.50–64.33% (Average 26.60 ± 3.81%). These observations suggest that canine primary intracranial histiocytic sarcomas tend to exhibit both dendritic cell and macrophage phenotypes of histiocytic differentiation.

Histiocytic sarcoma with central nervous system involvement in dogs: 19 cases (2006-2012)

Background

Reports of histiocytic sarcoma (HS) involving the central nervous system (CNS) are sparse and consist mainly of case reports describing 1–3 animals.

Objective

The objective of this study was to report the signalments, clinical signs, clinicopathologic and diagnostic imaging findings, treatment, and outcome of a series of dogs with HS and CNS involvement.

Animals

Nineteen dogs with HS examined at veterinary referral hospitals.

Methods

Retrospective case series. Medical records were reviewed and cases with a histopathological diagnosis of CNS HS were included in the study. Diagnostic imaging studies of the CNS were evaluated and histopathologic samples were reviewed to confirm the diagnosis.

Results

Retrievers and Pembroke Welsh Corgis were overrepresented in this cohort of dogs. Tumors involved the brain in 14 dogs and the spinal cord in 5. In 4 dogs, HS was part of a disseminated, multiorgan process whereas it appeared confined to the CNS in 15 dogs. Diagnostic imaging had variable appearances although extraaxial masses predominated in the brain. There was meningeal enhancement in all dogs that was often profound and remote from the primary mass lesion. Pleocytosis was present in all dogs with CSF evaluation. Median survival was 3 days.

Conclusions and Clinical Importance

Breed predispositions appear to vary from reports of HS in other organ systems. Some unique imaging and clinicopathologic characteristics, particularly brain herniation, profound meningeal enhancement, and pleocytosis in combination with 1 or more mass lesions, might help to differentiate this neoplasm from others involving the CNS, although this requires further study.

Imaging diagnosis--spinal cord histiocytic sarcoma in a dog

A 12-year-old mixed breed dog was presented for evaluation of progressive paraparesis and ataxia. Magnetic resonance (MR) imaging was performed and identified multifocal intradural spinal cord mass lesions. The lesions were hyperintense in T2-weighted sequences, isointense to mildly hyperintense in T1-weighted sequences with strong contrast enhancement of the intradural lesions and spinal cord meninges. Spinal cord neoplasia was suspected. A diagnosis of intramedullary spinal cord histiocytic sarcoma, confined to the central nervous system, was confirmed histopathologically. Spinal cord histiocytic sarcoma is a rare neoplasm, but should be included in the differential diagnosis for dogs with clinical signs of myelopathy.

Diagnostic immunohistochemistry of canine and feline intracalvarial tumors in the age of brain biopsies

The focus of immunohistochemistry as applied to nervous system tumors is in identifying the neoplasm present and evaluating margins between normal and neoplastic tissue. Although not always utilized by specialists in neuropathology, immunohistochemistry remains useful to resolve concerns about the differentiation and rate of tumor growth. The aims of this review are to discuss the utility of immunohistochemical reagents currently used in diagnosis of canine and feline intracalvarial tumors, to indicate the applicability of some tests currently used in human nervous system tumors for domestic species, and to evaluate a few less commonly used reagents. A panel of biomarkers is usually needed to confirm a diagnosis, with groups of reagents for leptomeningeal, intraparenchymal, and ventricular neoplasms. In the future, signature genetic alterations found among feline and canine brain tumors--as correlated prospectively with diagnosis, rate of enlargement, or response to treatment--may result in new immunohistochemical reagents to simplify the task of diagnosis. Prospective studies determining the type and proportion of stem cell marker expression on patient longevity are likely to be fruitful and suggest new therapies. Due to increased frequency of biopsy or partial resection of tumors from the living patient, biomarkers are needed to serve as accurate prognostic indicators and assist in determining the efficacy of developing therapeutic options in nervous system tumors of dogs and cats.

Primary leptomeningeal histiocytic sarcoma in a patient with a good outcome: a case report and review of the literature

Introduction

Histiocytic sarcoma is a rare neoplasm with few cases reported in the literature of which some were diagnosed in animals. This neoplasm arises from abnormal reticuloendothelial system cell proliferation of histiocytes and has an aggressive behavior especially if located in the central nervous system. We present the first case of a patient with histiocytic sarcoma that involved the meninges and had a good course after multidisciplinary treatment.

Case presentation

Our patient was a 41-year-old Caucasian woman with no previous history of disease who started with systemic symptoms such as headache and chills. Magnetic resonance imaging with gadolinium contrast of the brain suggested a mass 1.5×2cm in diameter in the temporal lobe with a non-uniform vasogenic edema. This lesion was implanted in the meninges and surgery was the first treatment. The histological findings revealed a histiocytic sarcoma. The patient received concomitant chemoradiotherapy after surgery with good tolerance and currently lives without disease.

Conclusion

Although histiocytic sarcomas in the brain present an unusual location and have a poorer prognosis, we have identified the first primary leptomeningeal histiocytic sarcoma with a disease-free survival greater than 3 years following multidisciplinary treatment with surgery and chemotherapy and radiotherapy.

Pathological and Immunohistochemical Features of Subdural Histiocytic Sarcomas in 15 Dogs

Subdural histiocytic sarcomas from 15 dogs (mean age: 7.8 years) were histopathologically examined. Among the 15 dogs, there was a marked breed predominance (toward Pembroke Welsh Corgi dogs, 47%), but no gender predilection. Focal solitary subdural masses were detected in the cerebrum (12 cases) and spinal cord (1 case), whereas diffuse infiltrative lesions were observed in the cerebral leptomeninges in 2 cases. All neoplastic lesions had common histological features characterized by the proliferation of pleomorphic histiocytic cells combined with various inflammatory reactions. Multinucleated giant cells, phagocytosis, and atypical mitotic figures in the neoplastic cells were commonly observed. Most of the pleomorphic neoplastic cells in the present cases were immunopositive for monocytic, histiocytic, or both markers, such as human leukocyte antigen (HLA)-DR, ionized calcium-binding adaptor molecule 1 (Iba1), cluster of differentiation (CD)163, and CD204, except for the neoplastic cells in 2 focal and 2 diffuse histiocytic sarcomas. The findings suggest that differences in cell origin, molecular expression, or both patterns are responsible for the distribution patterns of canine subdural histiocytic sarcomas.

Histiocytic sarcoma in the brain of a cat

A mass lesion in the subependymal region of the lateral ventricle in a 13-year-old neutered male mongrel cat with a complaint of somnolence, right circling movement and posture abnormality was examined. The magnetic resonance image examination revealed a relatively large T1-hypointense and T2-hyperintense mass lesion in the left interventricular foramen region, and there were no abnormalities in the chest and abdominal x-ray radiographic, funduscopic, and electric retinogram findings. The cat was died 43 days after the initial referral, and the post-mortem examinations revealed a poorly demarcated subependymal mass. Histologically, the brain lesion consisted of complex proliferation of highly pleomorphic cells resembling histiocytes with atypia and abundant mitotic figures. Moderate infiltrates of small reactive lymphocytes were admixed with the pleomorphic cell population. Gemistcytic astrocytes were also intermingled with the periphery of neoplastic foci. Immunohistochemically, most of the pleomorphic cells were positive for HLA-DR alpha-chain and ionized calcium binding adaptor molecule 1, and few were positive for lysozyme and alpha-1 antichymotrypsin. The atypical pleomorphic cells were negative for CD3, IgG (H and L), glial fibrillary acidic protein and neurofilament, suggesting monocytic/histiocytic-origin of the cells. The number of Ki-67-positive cell nuclei was extremely large, reflecting the high growth activity of these cells. Based on the findings, the lesion was considered as histiocytic sarcoma.

MR imaging of histiocytic sarcoma of the canine brain

Histiocytic sarcomas are characterized by proliferation and/or infiltration of neoplastic histiocytes localized to specific organs, unlike malignant histiocytosis which involves many organ systems. Only a few cranial histiocytic sarcomas have been reported. Here we describe four dogs that presented with neurological deficits referable to the forebrain, and were diagnosed histologically as having histiocytic sarcoma. Using magnetic resonance (MR) imaging, the tumors were characterized by a T2-hyperintense and T1-isointense mass in one dog, T2- and T1-isointense extraaxial masses in two dogs, and a diffuse T2-hyperintense lesion over the left cerebral cortex in one dog. All tumors had contrast enhancement. MRI features in three of the four dogs were similar to that of meningioma, supported by the observation of a dural tail in two of these three dogs, and a broad base of attachment in the other. In the other dog the imaging findings were similar to those of encephalitis. Intracranial histiocytic sarcoma does not appear to have specific MR imaging features and can be confused with meningioma or encephalitis.

Brain tumours in two Bactrian camels: a histiocytic sarcoma and a meningioma

Primary brain tumours were identified in two Bactrian camels (Camelus bactrianus) living at the Zoological Society of London's two zoos. Histology and immunohistochemistry were used to diagnose a histiocytic sarcoma in a 16-year-old female and a fibroblastic meningioma in a 13-year-old male. Before one died and the other was euthanased both camels had shown progressive neurological signs, including circling and ataxia.

Establishment and biological characterization of canine histiocytic sarcoma cell lines

Seven novel cell lines from canine histiocytic sarcoma (HS), three of which were disseminated cutaneous HS and four of which were synovial HS, were established. All of the established cell lines had the same morphological (by light and electron microscopic findings), cytochemical (alpha-naphthyl butyrate esterase-positive), and immunohistochemical (vimentin- and lysozyme-positive, and cyto-keratin-negative) characteristics as the original HS tumor cells. All of the established cell lines injected into nude mice subcutaneously produced solid tumors. Because the established cell lines also showed phagocytic and processing activities, the HS tumor cells appear to originate from the mononuclear phagocytic system cells, despite their differences in locations or organs.

Malignant Histiocytosis of the Brain in Three Dogs

Three dogs (two Rottweilers and a Flat-coated retriever) showed various neurological signs, including apathy, depression, circling, a partial decrease in functions associated with cranial nerves, seizures, hyperaesthesia, proprioceptive deficits, and increased spinal reflexes. In all three cases, necropsy revealed a solid, distinct, white mass in the brain and multiple, poorly demarcated, firm nodular proliferations in the lung; in one case the liver was also affected. Histopathological examination showed loosely aggregated, pleomorphic cells, with abundant eosinophilic cytoplasm. The neoplastic cells sometimes contained vacuoles or phagocytized cells. Binucleated and multinucleated giant cells, and mitotic figures, were common. Immunohistochemically, the tumour cells reacted strongly for lysozyme and vimentin, but there was no reaction for S-100 protein, cytokeratin, CD3 or CD79a. The histological and immunohistochemical examinations indicated a histiocytic origin of the tumour cells and malignant histiocytosis was therefore diagnosed.

Primary gastric histiocytic sarcoma in a dog--a case report

A 12-year-old intact female mixed breed dog was presented for chronic, intermittent vomiting and diarrhoea. On endoscopic examination a protruding mass arising from the mucosal surface of the pyloric region was detected. Cytological and histological examination revealed an accumulation of pleomorphic round/oval phagocytic cells suggesting histiocytic origin. This was confirmed by immunohistochemistry. No extra-gastric involvement was detected on clinical examination or at necropsy. This is the first report of primary gastric histiocytic sarcoma in a dog.

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.

Leptomeningeal metastases

LM is an increasingly common neurologic complication of cancer with variable clinical manifestations. Although there are no curative treatments, currently available therapies can preserve neurologic function and potentially improve quality of life. Further research into the mechanisms of leptomeningeal metastasis will elucidate molecular and cellular pathways that may allow identification of potential targets to interrupt this process early or to prevent this complication. Animal models are needed to further define the pathophysiology of LM and to provide an experimental system to test novel treatments [242-245]. There is an urgent need to develop new drug-based or radiation-based treatments for patients with LM. Randomized clinical trials are the appropriate study design to determine the efficacy of new treatments for LM. However, surrogate markers for response must be developed to facilitate the identification of effective regimens. Survival is not the optimal end point for such studies as most patients who develop this complication already have advanced, incurable cancer. Prevention of or delay in neurologic progression is one objective that has been utilized in recent randomized trials in patients with LM, and this end point deserves further attention. Although the development of LM represents a poor prognostic marker in patients with cancer it is important for physicians to recognize the symptoms and signs of the disease and establish the diagnosis as early in the disease course as possible. This may provide an opportunity for effective intervention that can improve quality of life, prevent further neurologic deterioration and, for a subset of patients, improve survival.

A Comparative Pathological Study on Granulomatous Meningoencephalomyelitis and Central Malignant Histiocytosis in Dogs

Histiocytic proliferative disorders in canine central nervous system (CNS) including granulomatous meningoencephalomyelitis (GME) and malignant histiocytosis were compared pathologically. Lesions of GME mainly existed in the white matter of the cerebrum, brainstem and cerebellum and consisted of characteristic perivascular cuffing, parenchymal granuloma and leptomeningeal infiltrates of mononuclear cells. In malignant histiocytosis, there were two histological patterns, diffuse proliferation of neoplastic histiocytes through the leptomeninges and neoplastic nodule formation in the parenchyma. Neoplastic histiocytes exhibited mild to severe cellular atypia and high ability of invasion into the brain parenchyma. Mitotic and phagocytic figures were also observed. Several histiocytic markers, including lysozyme, alpha1-antitrypsin and lectin RCA-1, revealed histiocytic origin of both inflammatory and neoplastic cells, however, those were not determinative for the discrimination between GME and malignant histiocytosis. CD3- and PCNA-positive cells existed in the lesions of both diseases. The number of CD3-positive cells in GME tended to be greater than in malignant histiocytosis, while the difference was not statistically significant.