Cerebrospinal fluid from a 10‐year‐old dog with a single seizure episode

Abstract

A cerebrospinal fluid sample collected from the cerebellomedullary cistern of a 10-year-old Shetland Sheepdog with a recent history of seizures was submitted for fluid analysis and cytologic examination. Key findings included a total nucleated cell count of 520/microL (reference interval 0-5 cells/microL), with a predominance of mononuclear cells, a protein concentration of 51.8 mg/dL (reference interval 0-35 mg/dL), and a glucose concentration of 44.7 mg/dL (reference interval 52-105 mg/dL). There was marked atypia of the mononuclear cells, with abundant eosinophilic cytoplasm, marked anisocytosis and anisokaryosis, occasional binucleated cells, mitotic figures, and rare erythrophagia. The cytologic interpretation was marked, monocytoid-rich, mixed cell pleocytosis with cellular atypia worrisome for neoplasia. In addition to histiocytic neoplasia, differentials included granulomatous meningoencephalomyelitis, necrotizing meningoencephalitis, and granulomatous inflammation. The dog did not respond to anti-inflammatory and anticonvulsive therapy. At necropsy, a mass involving the meninges and subtending the neuropil of the right temporal lobe of the cerebrum was found. Histologically, the mass was composed of large, bizarre histiocytic cells with multinucleated forms and numerous mitotic figures. Using immunochemistry on cytologic and histologic samples, the pleomorphic histiocytic cells were positive for CD1c, CD11ad, CD45, lysozyme, and vimentin, and were negative for CD3, CD4, CD79a, CD90, and pancytokeratin. These findings supported a diagnosis of primary CNS malignant histiocytosis of dendritic antigen-presenting cell (CD1c+) origin. To our knowledge, this is only the third reported case of primary CNS histiocytic sarcoma in dogs, and the first to demonstrate strong immunochemical evidence for dendritic antigen-presenting cell origin.

Histiocytic Sarcoma with Central Nervous System Involvement in Dogs: 19 Cases (2006–2012)

“…In this study, all dogs that had CSF evaluation had a pleocytosis along with increased CSF protein, which is consistent with previous reports of CNS HS 6, 8, 9, 10, 11, 20. An inflammatory response was considered likely to account for this pleocytosis in most of our cases as overtly neoplastic cells were not identified in this case series.…”

“…Although reported relatively infrequently in the veterinary literature,3, 4, 5, 6, 7, 8, 9, 10, 11, 12 HS with CNS involvement is being recognized more frequently. At our institution (NCSU), we were unable to document a case of HS with CNS involvement before 2006, but confirmed 19 cases from 2006 to 2012.…”

“…An inflammatory response was considered likely to account for this pleocytosis in most of our cases as overtly neoplastic cells were not identified in this case series. Several previous reports have described neoplastic histiocytes on CSF evaluation, often with the aid of immunocytochemistry 8, 9, 11, 20, 22. The neoplastic histiocytes might be driving an inflammatory response, reflected in the CSF evaluation, perhaps through the secretion of proinflammatory cytokines and chemokines.…”

“…Although CNS involvement has been recognized in dogs with disseminated (secondary) HS,2, 3 published reports of HS confined to the CNS (primary HS) are uncommon4, 5, 6, 7, 8, 9, 10, 11, 12 and most describe single cases or small numbers of dogs. The purpose of this report is to document the clinical, diagnostic, and pathologic findings as well as treatment and outcome in a larger case series of dogs with a confirmed diagnosis of HS involving the CNS.…”

Histiocytic Sarcoma in the Brain of a Cat

“…Histiocytic sarcoma (HS) in cats has been reported to date in the intestinal wall, femur, tarsus, spleen and liver, and mediastinal and vertebral canals [1,5,11,13,16]. A brief description of an HS in the central nervous system (CNS) of a cat was reported only in a review article [19], while malignant histiocytic disorders have been well demonstrated in the canine CNS [2,4,14,18,20]. This report documents the features of a brain tumor in a cat.…”