Histiocytic sarcoma with central nervous system involvement in 6 cats

MRI of a presumptive intracranial histiocytic sarcoma with extracranial extension in a cat

Case summary

A 4-year-old female neutered Scottish Fold shorthair cat was presented for further investigation of circling towards the right. MRI of the brain revealed an extensive, right-sided temporal muscle lesion with associated frontotemporal bone osteolysis, intracranial, extra-axial extension along the calvarial convexity with severe pachy- and leptomeningeal thickening and contrast enhancement, and an intra-axial space-occupying lesion in the right piriform lobe. The regional lymph nodes were moderately enlarged. Cytology of the right parotid lymph node and the temporal muscle was performed and histiocytic sarcoma (HS) was diagnosed. The owners elected euthanasia.

Relevance and novel information

HS of the central nervous system (CNS) is a very rare neoplastic condition in cats. Although a few case reports mention MRI, to our knowledge, the characterisation of MRI features of feline CNS HS have not been investigated in detail. Therefore, the aim of this case report was to describe the MRI characteristics in a feline HS involving not only the CNS, but also the fronto-temporal bone, temporal muscle and the regional lymph nodes. In particular, aggressive neoplastic bone invasion was a novel finding.

Diagnostic immunohistochemistry of primary and secondary central nervous system neoplasms of dogs and cats

The diagnosis of primary and secondary CNS neoplasms of dogs and cats relies on histologic examination of autopsy or biopsy samples. In addition, many neoplasms must be further characterized by immunohistochemistry (IHC) for a more refined diagnosis in specific cases. Given the many investigations assessing the diagnostic and prognostic IHC profile of CNS neoplasms in the veterinary literature, it may be difficult for the diagnostic pathologist or pathology trainee to narrow the list of reliable diagnostic IHCs when facing a challenging case. Here we compile a comprehensive list of the most diagnostically relevant immunomarkers that should be utilized for the diagnostic support or confirmation of the most common primary and secondary CNS neoplasms of dogs and cats.

Bilateral renal histiocytic sarcoma with disseminated lung involvement in a Siberian Forest Cat

Case summary

A 5-year-old female neutered Siberian Forest Cat presented with a 7-day history of lethargy, hyporexia and weight loss. Abdominal ultrasonography revealed bilateral renal changes suggestive of neoplasia. Thoracic radiography documented diffuse pulmonary nodules. The cat was euthanased during diagnostic investigations. Histopathological assessment and immunohistochemical staining of post-mortem renal biopsies were consistent with a histiocytic lesion, most likely histiocytic sarcoma (HS). The lung lesions were suspected of representing disseminated disease.

Relevance and novel information

HS is considered a rare neoplastic process in cats. This report describes a case of feline bilateral renal HS with suspected concomitant pulmonary involvement. A primary renal origin was suspected, with the lung lesions being a result of disseminated disease. Renal HS should be included as a differential diagnosis when renal ultrasonography reveals changes suggestive of neoplasia.

A review of primary central nervous system neoplasms of cats

Primary central nervous system (CNS) neoplasms are uncommonly diagnosed in cats. The majority of primary feline CNS neoplasms described in the veterinary literature consist of meningioma and glioma occurring mainly in the brain and less often in the spinal cord. Although most neoplasms can be diagnosed based on routine histologic evaluation, less typical tumors need to be further characterized using immunohistochemistry. This review compiles the relevant information about the most common primary CNS neoplasms of cats available in the veterinary literature, aiming to serve as a converging source of information for the topic.