Objective—To document computed tomography (CT) features in dogs with masticatory myositis.
Design—Retrospective case series.
Animals—7 dogs with an immunologic diagnosis of masticatory myositis and an absence of clinical abnormalities of any skeletal muscles other than the masticatory muscles.
Procedures—History; clinical, hematologic, biochemical, immunologic, cytologic, and histologic findings; and pre- and postcontrast CT imaging features of masticatory muscles and head and neck lymph nodes were extracted from medical records.
Results—On CT images, changes in size (atrophy or swelling) were common for all masticatory muscles except the digastricus muscles, which were involved only in 1 dog. Pre-contrast attenuation changes, most often hypoattenuation with varied distribution patterns, were seen in masticatory muscles of 4 dogs. Contrast enhancement with a predominantly inhomogeneous distribution pattern was seen in the temporalis, masseter, and pterygoid muscles of all dogs. Head and neck lymph nodes were enlarged in all but 1 dog and had contrast enhancement with predominantly central or homogeneous distribution patterns. Muscle biopsy was performed in 6 dogs, with biopsy specimens obtained from areas that had the most obvious contrast enhancement on CT images. For all 6 dogs, biopsy speci-mens had histologic features indicative of masticatory myositis.
Conclusions and Clinical Relevance—Results suggested that CT may be a useful adjunct in the diagnosis of masticatory myositis in dogs, including selection of sites for diagnostic muscle biopsy.
Case Description—Two 6-year-old male dogs were evaluated for removal of midline occipito-temporal multilobular osteochondrosarcomas.
Clinical Findings—Physical examination revealed mild ataxia in 1 dog and large masses of the central occipitotemporal portion of the skull in both dogs. Computed tomography, magnetic resonance imaging (MRI), or both revealed large bone-origin occipitotemporal masses with impingement of the brain and the sagittal and transverse venous sinuses. Three-dimensional contrast magnetic resonance image reconstruction delineated collateral venous circulation around the tumor and venous sinus occlusion in 1 dog.
Treatment and Outcome—Tumors in both dogs were surgically removed and the skull defects repaired with polymethyl methacrylate prostheses. Twenty-four hours after surgery, 1 dog had normal mentation, cranial nerve function, and conscious proprioceptive responses, whereas the other dog had depressed mentation but no neurologic deficits. Both dogs were discharged 4 days after surgery with normal mentation and no neurologic deficits.
Clinical Relevance—Findings suggested that MRI and computed tomography can play a key role in assessment of essential cortical collateral circulation when surgical removal of tumors is likely to result in bilateral disruption of transverse venous sinuses. Without robust collateral circulation and proper preoperative planning, removal of massive skull tumors in the midline occipitotemporal region will likely result in substantial morbidity or death. However, results in the 2 dogs reported here indicate the feasibility of removing such tumors with good outcomes in the presence of well-developed collateral venous drainage.
Objective—To describe the computed tomographic features of oral squamous cell carcinoma (SCC) in cats and identify imaging characteristics associated with survival time.
Design—Retrospective case series.
Animals—18 cats with a diagnosis of oral SCC.
Procedures—Information on history; clinical, laboratory, and diagnostic imaging findings; treatment; and survival time was obtained from medical records of 18 cats with oral SCC. Computed tomography (CT) studies were examined to identify features associated with oral SCC. The association of CT features with survival time was evaluated.
Results—On CT images, SCC was centered at the following sites: sublingual or lingual region (n = 7), maxilla (5), buccal mucosa (4), mandible (4), pharyngeal mucosa (2), soft palate mucosa (1), and lip (1). These results were in agreement with the results of oral examination for all sites, except the soft palate (CT, 1 cat; oral examination, 4 cats). On CT images, extension of maxillary masses was most often observed to affect the orbit (5 cats). Heterogeneous contrast enhancement was most commonly identified (8/18). Osteolytic mass lesions were identified on CT images in 9 cats. None of the quantitative CT features that were identified, including mass size, attenuation, or lymph node width, were correlated with survival time.
Conclusions and Clinical Relevance—Common CT features of oral SCC in cats included sublingual and maxillary locations, marked heterogeneous contrast enhancement, and osteolysis. Computed tomography may be used to determine mass extension and lymph node enlargement, but results did not correlate with survival time.
Case Description—A 6-year-old neutered male Boston Terrier was examined to determine the cause of sneezing, bilateral nasal discharge, nasal congestion, lethargy, and coughing of 2 months' duration.
Clinical Findings—An undifferentiated nasal carcinoma was diagnosed. During computed tomography (CT) evaluation of response to tomotherapy radiation treatment, a mandibular dentigerous cyst, associated with an unerupted left mandibular first premolar, was monitored for expansion.
Treatment and Outcome—The dog had a profound response to radiation treatment, and the nasal carcinoma totally resolved. It was determined on the basis of CT that the rate of expansion of the dentigerous cyst was placing the dog at risk for mandibular fracture and loss of vitality to the surrounding teeth. The unerupted left mandibular first premolar and associated dentigerous cyst were surgically removed and submitted for histologic evaluation.
Clinical Relevance—Images obtained during sequential CT evaluations performed after radiation treatment of nasal carcinoma should be examined for evidence of the primary neoplasm as well as to detect unrelated lesions of the orofacial region that can compromise the quality of life. Findings of CT evaluations can be used to determine when and how to initiate treatment for dentigerous cysts in regard to the patient's response to radiation treatment.