Clinicopathological characteristics of histiocytic sarcoma affecting the central nervous system in dogs.

Izumi Toyoda,Kevin Woolard,Chelsea M Crowe,Kurt Zimmerman,Beverly K Sturges,Robert J Higgins,Peter J Dickinson,Karen M Vernau,John Rossmeisl,William Vernau,Michelle Giuffrida

doi:10.1111/jvim.15673

Abstract

BackgroundHistiocytic sarcoma affecting the central nervous system (CNS HS) in dogs may present as primary or disseminated disease, often characterized by inflammation. Prognosis is poor, and imaging differentiation from other CNS tumors can be problematic.ObjectiveTo characterize the clinicopathological inflammatory features, breed predisposition, and survival in dogs with CNS HS.AnimalsOne hundred two dogs with HS, 62 dogs with meningioma.MethodsRetrospective case series. Records were reviewed for results of cerebrospinal fluid (CSF) analysis, CBC, treatment, and outcome data.ResultsPredisposition for CNS HS was seen in Bernese Mountain Dogs, Golden Retrievers, Rottweilers, Corgis, and Shetland Sheepdogs (P ≤ .001). Corgis and Shetland Sheepdogs had predominantly primary tumors; Rottweilers had exclusively disseminated tumors. Marked CSF inflammation was characteristic of primary rather than disseminated HS, and neoplastic cells were detected in CSF of 52% of affected dogs. Increased neutrophil to lymphocyte ratios were seen in all groups relative to controls (P <.008) but not among tumor subtypes. Definitive versus palliative treatment resulted in improved survival times (P < .001), but overall prognosis was poor.Conclusions and Clinical ImportanceClinicopathological differences between primary and disseminated HS suggest that tumor biological behavior and origin may be different. Corgis and Shetland Sheepdogs are predisposed to primary CNS HS, characterized by inflammatory CSF. High total nucleated cell count and the presence of neoplastic cells support the use of CSF analysis as a valuable diagnostic test. Prognosis for CNS HS is poor, but further evaluation of inflammatory mechanisms may provide novel therapeutic opportunities.

Highlights

Histiocytic sarcomas (HS) are tumors that arise typically from interstitial dendritic cells[1,2] and may occur as localized disease or as disseminated disease affecting multiple organs
A Fisher's exact test was used to compare the distribution of HS within each breed relative to the entire population of dogs admitted to the University of California (UC) Davis Veterinary Medical Teaching Hospital (VMTH) during the retrospective period, and the corresponding odds ratios were presented with surrounding 95% confidence intervals (CI)
Primary and disseminated central nervous system (CNS) HS were shown to differ in terms of inflammatory response based on cerebrospinal fluid (CSF) analysis, different breed predisposition, and different anatomical locations of disease, with disease affecting the spinal cord

Summary

Introduction

Histiocytic sarcomas (HS) are tumors that arise typically from interstitial dendritic cells[1,2] and may occur as localized disease or as disseminated disease affecting multiple organs. Several dog breeds are consistently overrepresented in HS case series, and a familial association has been reported in Bernese Mountain Dogs.[3,4,5] Defined breed predisposition data for HS are limited, but Bernese Mountain Dog, Golden Retriever, Flat Coat Retriever, Shar Pei, Miniature Schnauzer, Labrador Retriever, and Pembroke Welsh Corgi breeds have been shown to be overrepresented based on defined control populations,[6,7] and Rottweilers are conspicuously overrepresented in several case series.[1,8,9,10,11] Histiocytic sarcoma involving the central nervous system (CNS) is relatively uncommon representing 2.2% (n = 2) of primary and 3.4% (n = 7) of secondary intracranial neoplasms diagnosed at necropsy,[12] and prognosis regardless of treatment is anecdotally poor.[13,14,15] Intracranial CNS HS commonly are reported as extra-axial, uniformly contrastenhancing masses on magnetic resonance (MR) imaging, and differentiation from more commonly occurring, and generally more benign extra-axial tumors such as meningioma can be challenging.[13,16,17]. Prognosis for CNS HS is poor, but further evaluation of inflammatory mechanisms may provide novel therapeutic opportunities

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