Cases

Case 1

Signalment/history

Nine-year-old, intact male Dandie Dinmont Terrier. The patient presented with a several-month history of listlessness, which progressed to depression and inability to rise.

Examination findings

On physical examination there was marked muscle atrophy of the left and right supraspinatus and left biceps muscles. There was moderate bilateral hindlimb ataxia and moderate left forelimb lameness. A mild right-sided head tilt was also noted. On neurologic examination, conscious proprioception was decreased in all four limbs but was more pronounced on the hindlimbs. There was moderate decreased panniculus at L3 and mild rotational nystagmus.

An MR study showed a contrast enhancing heterogeneous region in the axilla. Adjacent to the fourth ventricle in the vermis was an area of contrast enhancement (Figure 14.51).

Figure 14.51 A T1-weighted post-contrast MR image from a 9-year-old Dandie Dinmont Terrier. An area of mild hyperintensity is present in the vermis adjacent to the fourth ventricle. (Image obtained and reviewed by a Diplomate of the American College of Veterinary Radiologists at Colorado State University, Fort Collins, Co.)

CSF analysis

A CSF sample was collected from the cerebellomedullary cistern and submitted for evaluation. The sample was clear and cloudy. It had a CSF TP = 46 mg/dl (normal of a cystic extra-axial mass near the cerebellum (Wright–Giemsa: a, 500? magnification; b–d, 1,000? magnification).

Cytology description

Much of the sample is very dense, preventing complete evaluation of the cytologic features (Figure 14.54a). There are cohesively clustered polygonal cells with basophilic slightly granular cytoplasm, an eccentrically located ovoid to round nucleus with stippled chromatin, and rarely a poorly distinct nucleolus (Figures 14.54b, c).

Interpretation: neoplasia; suspect choroid plexus tumor or meningioma.

Outcome

On histopathology, there was a solid, multilobular neoplasm of polygonal cells and minimal stroma (Figures 14.55a–d). The cells had eosinophilic cytoplasm, indistinct cell borders, round nuclei with smudged chromatin and 1–2 prominent nucleoli. Rarely, cells had intranuclear cytoplasmic pseudoinclusions; folded nuclei were found (Figure 14.55d). There was mild anisocytosis and anisokaryosis and a low mitotic index. The histologic diagnosis was meningothelial meningioma. The patient was started on a course of stereotactic radiation therapy and is progressing appropriately at the time of writing.

Figures 14.55a–d Histologic sections of a meningothelial meningioma in an 8-year-old Labrador Retriever. (a) Sheets and lobules of neoplastic cells are present; fibrin and red blood cell clumps are seen along the edge of the image. (b) Note how the neoplastic cells are arranged around the blood vessel. (c) The neoplastic cells are polygonal with poorly distinct cell margins, eosinophilic cytoplasm, round nuclei, peripheralized chromatin, and one to several nucleoli. (d) Two of the characteristic findings in this tumor type are displayed: intranuclear cytoplasmic pseudoinclusions (long arrow) and folded nuclei (short arrows) (H&E: (a) and (b), 200? magnification; c, 500? magnification; d, 1,000? magnification).

CASE 3

Signalment/history

Two-year-old, spayed female German Shepherd. The patient had a 1-week history of inability to stand, acute blindness, and collapse episodes.

Examination findings

On neurological examination, the patient had a dull mentation with non-ambulatory tetraparesis and ventroflexion of the head and neck. Pupillary light response was absent on the left and decreased on the right with possible swelling of the left optic nerve on fundic examination.

CSF analysis

A CSF sample was collected from the cerebellomedullary cistern and submitted for evaluation. The sample was clear and colorless. It had a CSF TP = 46.7 mg/dl (normal fluid for diagnosis of feline infectious peritonitis involving the central nervous system in cats. J Am Vet Med Assoc 230(2):199–205.

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