CPB 697 RESEARCH SEMINAR
Ikki Mitsui, BVM
Graduate Student in Anatomic Pathology
Department of Comparative Pathobiology
In The Nasal Cavity
Of A Dog”
Thursday,
April 17, 2008
VPTH
112
3:30
pm
Abstract:
I. Mitsui, M. Logan, L. Adams, B. Eyden, J. A. Ramos-Vara, S. Lenz
Malignant peripheral nerve sheath tumor (MPNST) with lipogenic and pseudo-hemangiopericytomatous differentiation was diagnosed in a 9-year-old male neutered mixed breed dog with 4-month history of epistaxis and inspiratory stridor. At presentation, the dog had a firm swelling around the left eye and maxillary region and left-sided mucopurulent ocular discharge and serosanguinous epistaxis. Polycythemia, monocytosis, hyperproteinemia, and unconjugated hyperbilirubinemia were mild by blood testings. Urinalysis detected 3+ bilirubinuria. Computer tomography revealed a soft tissue opacity in the left nasal cavity and adjacent frontal sinus. The dog died during the recovery from the anesthesia. At necropsy, bilateral intranasal masses with mucopurulent rhinitis and frontal sinusitis were detected. Histologically, the nasal conchae were expanded and effaced by infiltrative sheets of neoplastic spindle cells arranged in interlacing fascicles or storiform patterns. Neoplastic spindle cells had clear cytoplasmic vacuoles and the stroma contained tortuous, anastomosing vascular spaces. Immunohistochemistry revealed diffuse cytoplasmic positivity for S-100. Ultrastructurally, lipid vacuoles and intermediate filaments were observed in the cytoplasm of tumor cells. A well developed basal lamina invested the tumor cell bodies and processes. Intercellular junctions, without characteristics of desmosome, were also observed. Final diagnosis of MPNST was made by results of these diagnostic tests. MPNST affecting the intranasal structure has not been reported in animals. Lipogenic or hemangiopericytomatous differentiation of MPNST has rarely or not been reported in veterinary medicine, respectively. These results confirm the potential occurrence of MPNST in the nasal cavity of animals and suggest pluripotent nature of cell of origin of MPNST.