The utility of intraoperative impression smear cytology of intracranial granular cell tumors: Three cases

Abstract

Dog 1, a 14-year-old male neutered Shih Tzu, was presented with a 6-month history of seizures. Abnormal findings on the neurologic examination included confused mentation, nonambulatory tetraparesis, right torticollis, absent menace, reduced vestibuloocular reflex, and spontaneous vertical jerk nystagmus in both eyes (OU). The patient also had left-sided facial weakness and left-sided hemi-inattention. Postural reactions were absent in all limbs. A neuroanatomic localization was assigned to the right prosencephalon and thalamus/ brainstem. Dog 2 was a 9-year-old female spayed Maltese with a history of seizures. The patient had experienced several mild seizures over the course of one month prior to presentation. Abnormal findings on the neurologic examination included obtunded mentation and historical Horner's syndrome. A neuroanatomic localization was assigned to the prosencephalon, along with a left sympathetic neuropathy (consistent with a historical Horner's syndrome). Abstract Two adult male dogs (a 7-year-old shorthaired Chihuahua and 14-year-old Shih Tzu) and one adult female dog (a 9-year-old Maltese) presented for evaluation of newonset seizure activity. Magnetic resonance imaging of the brain demonstrated a large, poorly marginated T2-weighted hyperintense, and strong contrast enhancing extra-axial mass in each case. A surgical biopsy for histopathologic evaluation was elected in all cases, and intraoperative impression smears were successfully obtained. Intraoperative cytology identified a homogenous population of round to polygonal cells with central to eccentric nuclei, coarse chromatin, and variably amphophilic to eosinophilic granular cytoplasm. Cytologic findings led to a suspected diagnosis of granular cell tumor (GCT) in all cases. Histopathologic review identified a densely cellular, unencapsulated neoplastic mass comprised of sheets of large round to polygonal cells with abundant eosinophilic cytoplasm containing numerous eosinophilic intracytoplasmic granules, confirming the diagnosis of GCT in all cases. The cases reported here are unique in that they reveal an accurate intraoperative cytologic diagnosis of a rare canine central nervous system neoplasm. Intraoperative cytology of the intracranial masses could provide clinicians with important and quick diagnostic and prognostic information; therefore, expediting decisions made intraoperatively. Further research is warranted to determine the diagnostic accuracy of intraoperative cytology for neoplasia in veterinary patients. K E Y W O R D S brain, canine, granular cell tumor, impression, neoplasia | 283 LEVITIN ET aL.

What's your diagnosis? Mass on the hard palate of a dog

“…This group also found that the microenvironment affects the morphology of the neoplastic GCT cells 4 . The cells contain abundant lysosomes, giving them a “granular” appearance 1‐5 . Oncocytomas originate from the duct of the glandular epithelium, usually in the oral cavity, salivary glands, or pharynx 1‐3 .…”

“…GCTs are most frequently found in the oral cavity of dogs and cats 1‐5 but can also be found in locations such as the brain, heart, lung, nerve roots, trachea, skin, and lymph nodes, 1,2 and eyelid 3 . GCT histogenesis is uncertain and might depend on the anatomic location of the tumor.…”

“…The cells contain abundant lysosomes, giving them a “granular” appearance 1‐5 . Oncocytomas originate from the duct of the glandular epithelium, usually in the oral cavity, salivary glands, or pharynx 1‐3 . The cells contain abundant mitochondria in the cytoplasm.…”

“…The cells contain abundant mitochondria in the cytoplasm. Rhabdomyomas have skeletal muscle origin, often appearing on the head and neck region, and contain abundant mitochondria 1‐3 . Finally, melanomas arise from the neural crest, which gives them the ability to exhibit a variety of morphologic features.…”

“…Finally, melanomas arise from the neural crest, which gives them the ability to exhibit a variety of morphologic features. They can be found throughout the body and contain melanin granules 1‐3 . Amelanotic melanomas do not have prominent granulation, making them challenging to diagnose.…”