Spinal Meningioma in a Dog
NECROPSY REQUEST
CLINICAL
DIAGNOSIS:
Open.
HISTORY: Paretic / down in rear about two months. Came to
neurology service. Foul urine -- found cystitis and pyometra. CT
showed intramedullary lesion, most likely neoplasia. CSF: very high
protein, few other cells.
CLINICAL QUESTIONS: Is spinal cord lesion intradural -
extramedullary or intramedullary?
NECROPSY GROSS REPORT
ANIMAL
IDENTIFICATION:
A 25.1kg, six-year-old, intact female English Pointer dog is presented for
necropsy in fair body condition.
INTEGUMENTARY AND SPECIAL SENSES: Shaved areas include: caudal dorsal
midline (20 x 12cm), left forelimb (7 x 6cm), right forelimb (8cm
circumferentially), dorsal neck (7.5 x 12cm), and the entire ventral abdomen
caudal to the xiphoid. A pedunculated skin tag (2 x 2cm) is lateral to the
caudal-most right teat.
URINARY (Right kidney weight: 96g; Left kidney weight: 102g): The
right and left kidneys are moderately edematous. Bilaterally, the medullae
contain a discrete round (1 x 0.5cm) lesion filled with thick grayish-green
tenacious material (suppurative exudate). Both kidneys have multifocal, light
tan to dark red streaks in the medulla, occasionally extending into the cortex
(suppurative pyelonephritis, presumed).
GENITAL: The uterus is enlarged with prominent, somewhat tortuous blood
vessels. The lumen contains abundant thick reddish-brown, malodorous fluid (pyometra).
MUSCULOSKELETAL: Bilateral muscle atrophy is apparent caudal to the
thoracolumbar junction (neurogenic atrophy, presumed).
NERVOUS (Brain weight: 88g): The spinal cord in the region of L3 and
L4 has a 5cm uniformly thickened segment measuring 1.5cm in width (intramedullary
neoplasia, presumed).
RESPIRATORY, CARDIOVASCULAR (Heart weight: 206g. The right
ventricular free wall is 6mm in width. The left ventricular free wall is 13mm
in width.), HEMIC AND LYMPHATIC (Spleen weight: 102g), LIVER
AND PANCREAS (Liver weight: 1.28kg), DIGESTIVE, ENDOCRINE:
No significant lesions observed.
POSTMORTEM ANALYSIS AND DIAGNOSIS: The cause of death is
euthanasia. Sectioning of the spinal cord will be done following fixation.
The pyelonephritis is presumably secondary to the pyometra. Histopathology of
selected tissues and bacterial culture of the kidney are pending.
TENTATIVE DIAGNOSIS: Intramedullary spinal neoplasm, presumed; Pyometra;
Pyelonephritis.
(Fig. 1 The spinal cord at L3-L4 is increased in diameter.)
(Fig. 2 On cross section, a mass (ventral) is compressing the spinal cord (dorsal).)
NECROPSY HISTOPATHOLOGY REPORT
MICROSCOPIC LESIONS:
Spinal cord (L3 to
cauda equina): Meningioma.
Spinal cord (thoracic and lumbar): Syringomyelia.
Kidney: Moderate to locally severe, multifocal, chronic, lymphoplasmacytic
and neutrophilic pyelonephritis, with focal abscess formation.
Skeletal muscle, hindlimbs: Mild to moderate, bilateral, myofiber atrophy,
with scattered myodegeneration.
Liver: Mild multifocal vacuolar (steroid) hepatopathy.
Spleen: Moderate, diffuse, extramedullary hematopoesis and thrombopoesis
Stomach, Small intestine, Colon, Heart, Lung, Brain: No significant lesions.
DIAGNOSIS: Meningioma, lumbar spinal cord; Pyometra; Pyelonephritis.
(Fig. 3 Histologically, neoplastic tissue is seen both compressing and invading the spinal cord parenchyma. The central canal (arrow) is displaced dorsally)
(Fig. 4 Higher magnification, showing the pleomorphic, spindle-shaped neoplastic cells.)
INTERPRETIVE SUMMARY/COMMENTS:
The neoplasm in the lumbar spinal cord is a highly invasive meningioma.
Several patterns of cell growth are present, with the papillary pattern
predominating. In humans, papillary meningiomas are known for their
invasiveness relative to most other subtypes of meningioma. Neoplastic cells
extended cranially into the mid-thoracic spinal cord and caudally to the cauda
equina. The changes in the skeletal muscles of the hind limbs are consistent
with neurogenic atrophy. A pure growth of E. coli was cultured from
the kidney, consistent with an ascending bacterial infection secondary to
pyometra.
ANCILLARY LABORATORY RESULTS:
Bacteriology -
Kidney: E. coli (2+).
Immunohistochemistry on neoplasm: Strong diffuse positivity for vimentin.
Negative for pancytokeratin.
