History
A 4-year-old 5.3-kg (11.7-lb) spayed female domestic longhair cat was referred for evaluation of a 2-week history of lethargy, reluctance to move, signs of cervical pain, and behavioral changes after the cat tried to jump onto a dresser, hit its head, and cried out. The owner reported that the cat also became unwilling to step up into the litterbox or up onto other surfaces and that the cat had an altered, crouched gait. The referring veterinarian empirically treated the cat with buprenorphine and prednisolone (dosages unknown); however, no improvement was noticed.
On physical examination, the cat had a hunched posture, right thoracic limb hopping deficit, and spinal hyperesthesia that was most pronounced in the cervical region. No other abnormalities were identified. The cat was anesthetized, and radiographs of the neck were obtained (Figure 1).
Right lateral (A) and ventrodorsal (B) radiographic views of the neck of a 4-year-old spayed female domestic longhair cat referred for evaluation of a 2-week history of lethargy, behavioral changes, and signs of neck pain and reluctance to move. The cat was anesthetized for radiography, and an endotracheal tube is evident in place.
Citation: Journal of the American Veterinary Medical Association 254, 8; 10.2460/javma.254.8.919
Right lateral (A) and ventrodorsal (B) radiographic views of the neck of a 4-year-old spayed female domestic longhair cat referred for evaluation of a 2-week history of lethargy, behavioral changes, and signs of neck pain and reluctance to move. The cat was anesthetized for radiography, and an endotracheal tube is evident in place.
Citation: Journal of the American Veterinary Medical Association 254, 8; 10.2460/javma.254.8.919
Right lateral (A) and ventrodorsal (B) radiographic views of the neck of a 4-year-old spayed female domestic longhair cat referred for evaluation of a 2-week history of lethargy, behavioral changes, and signs of neck pain and reluctance to move. The cat was anesthetized for radiography, and an endotracheal tube is evident in place.
Citation: Journal of the American Veterinary Medical Association 254, 8; 10.2460/javma.254.8.919
Determine whether additional imaging studies are required, or make your diagnosis from Figure 1—then turn the page →
Diagnostic Imaging Findings and Interpretation
On radiographic examination, diffuse homogeneous soft tissue swelling was present along the ventral aspect of the cervical vertebrae, resulting in ventral and right lateral displacement of the pharynx and trachea. There was no evidence of bone involvement, embedded foreign material, or inclusion of gas in the affected area (Figure 2). Differential diagnoses considered for the lesion included inflammation (eg, retroesophageal abscess or cellulitis), hematoma, seroma, or diffuse infiltrative neoplasia (less likely). The location and extent of the swelling were inconsistent with lesions originating from the retropharyngeal lymph nodes, salivary glands, or thyroid gland. Similarly, an esophageal origin was considered unlikely because there was no history of regurgitation and no radiographic evidence of intraluminal gas typically seen with esophageal masses.
Same radiographic images as in Figure 1. There is no evidence of bone involvement, embedded foreign material or inclusion of gas; however, a diffuse homogeneous soft tissue swelling (asterisk; A) ventral to the cervical region of the vertebral column causes ventral displacement of the pharynx and trachea. In addition, right lateral deviation of the trachea with the indwelling endotracheal tube (arrows; B) is evident.
Citation: Journal of the American Veterinary Medical Association 254, 8; 10.2460/javma.254.8.919
Same radiographic images as in Figure 1. There is no evidence of bone involvement, embedded foreign material or inclusion of gas; however, a diffuse homogeneous soft tissue swelling (asterisk; A) ventral to the cervical region of the vertebral column causes ventral displacement of the pharynx and trachea. In addition, right lateral deviation of the trachea with the indwelling endotracheal tube (arrows; B) is evident.
Citation: Journal of the American Veterinary Medical Association 254, 8; 10.2460/javma.254.8.919
Same radiographic images as in Figure 1. There is no evidence of bone involvement, embedded foreign material or inclusion of gas; however, a diffuse homogeneous soft tissue swelling (asterisk; A) ventral to the cervical region of the vertebral column causes ventral displacement of the pharynx and trachea. In addition, right lateral deviation of the trachea with the indwelling endotracheal tube (arrows; B) is evident.
Citation: Journal of the American Veterinary Medical Association 254, 8; 10.2460/javma.254.8.919
To further assess the extent of the lesion and rule out involvement of the vertebrae and vertebral canal, MRI was performed (Figure 3). A large fusiform mass was identified extending from the level of C2 to T4 in the cervical and mediastinal soft tissues and causing ventral displacement of the trachea and esophagus. Compared with adjacent musculature, the lesion was markedly hyperintense on T2-weighted and iso- to hyperintense on T1-weighted MRI images. In addition, on MRI images captured following administration of contrast medium to the cat, the periphery of the mass had intense rim enhancement and the adjacent soft tissues had moderate, diffuse contrast enhancement. The center of the mass did not have contrast enhancement. There was no evidence of involvement of the vertebrae or vertebral canal. On the basis of lesion location and imaging characteristics, a diagnosis of retroesophageal abscess and adjacent cellulitis was made.
Sagittal (A) and transverse (B) T2-weighted, sagittal (C) and transverse (D) T1-weighted, and sagittal (E) and transverse (F) postcontrast T1-weighted MRI images with fat suppression of the cat in Figures 1 and 2. A large fusiform mass (arrows) extends from the level of C2 to T4 and causes ventral and right lateral displacement of the trachea and esophagus (arrowheads; F). Compared with adjacent musculature, the lesion is markedly hyperintense on T2-weighted (A, B) and iso- to hyperintense on T1-weighted (C, D) images. Following contrast medium administration, the periphery of the mass has intense rim enhancement, the center of the mass lacks enhancement, and the adjacent soft tissues have moderate, diffuse contrast enhancement (E, F). There is no evidence of involvement of the cervical vertebrae or vertebral canal.
Citation: Journal of the American Veterinary Medical Association 254, 8; 10.2460/javma.254.8.919
Sagittal (A) and transverse (B) T2-weighted, sagittal (C) and transverse (D) T1-weighted, and sagittal (E) and transverse (F) postcontrast T1-weighted MRI images with fat suppression of the cat in Figures 1 and 2. A large fusiform mass (arrows) extends from the level of C2 to T4 and causes ventral and right lateral displacement of the trachea and esophagus (arrowheads; F). Compared with adjacent musculature, the lesion is markedly hyperintense on T2-weighted (A, B) and iso- to hyperintense on T1-weighted (C, D) images. Following contrast medium administration, the periphery of the mass has intense rim enhancement, the center of the mass lacks enhancement, and the adjacent soft tissues have moderate, diffuse contrast enhancement (E, F). There is no evidence of involvement of the cervical vertebrae or vertebral canal.
Citation: Journal of the American Veterinary Medical Association 254, 8; 10.2460/javma.254.8.919
Sagittal (A) and transverse (B) T2-weighted, sagittal (C) and transverse (D) T1-weighted, and sagittal (E) and transverse (F) postcontrast T1-weighted MRI images with fat suppression of the cat in Figures 1 and 2. A large fusiform mass (arrows) extends from the level of C2 to T4 and causes ventral and right lateral displacement of the trachea and esophagus (arrowheads; F). Compared with adjacent musculature, the lesion is markedly hyperintense on T2-weighted (A, B) and iso- to hyperintense on T1-weighted (C, D) images. Following contrast medium administration, the periphery of the mass has intense rim enhancement, the center of the mass lacks enhancement, and the adjacent soft tissues have moderate, diffuse contrast enhancement (E, F). There is no evidence of involvement of the cervical vertebrae or vertebral canal.
Citation: Journal of the American Veterinary Medical Association 254, 8; 10.2460/javma.254.8.919
Following MRI, an abbreviated ultrasonographic examination of the neck was performed to identify an acoustic window for diagnostic sampling of the lesion. An accumulation of echogenic fluid with flocculent material surrounded by an irregularly marginated hyperechoic wall was identified dorsal to the trachea and esophagus. Adjacent fat was mildly and diffusely hyperechoic (Figure 4).
Sagittal color-flow Doppler ultrasonographic image of the retroesophageal mass of the cat in the previous figures. In the center of the image, a collection of echogenic fluid with flocculent material is surrounded by a hyperechoic wall and mildly hyperechoic adjacent fat. There is no evidence of blood flow in the center of the lesion.
Citation: Journal of the American Veterinary Medical Association 254, 8; 10.2460/javma.254.8.919
Sagittal color-flow Doppler ultrasonographic image of the retroesophageal mass of the cat in the previous figures. In the center of the image, a collection of echogenic fluid with flocculent material is surrounded by a hyperechoic wall and mildly hyperechoic adjacent fat. There is no evidence of blood flow in the center of the lesion.
Citation: Journal of the American Veterinary Medical Association 254, 8; 10.2460/javma.254.8.919
Sagittal color-flow Doppler ultrasonographic image of the retroesophageal mass of the cat in the previous figures. In the center of the image, a collection of echogenic fluid with flocculent material is surrounded by a hyperechoic wall and mildly hyperechoic adjacent fat. There is no evidence of blood flow in the center of the lesion.
Citation: Journal of the American Veterinary Medical Association 254, 8; 10.2460/javma.254.8.919
Treatment and Outcome
Ultrasonographically guided fine-needle aspiration and drainage of the lesion yielded thick yellow to brown fluid with flocculent material. Results of cytologic evaluation of the fluid were consistent with a mixed bacterial infection and marked neutrophilic inflammation. Bacterial culture of the fluid sample was performed, and the cat was prescribed amoxicillin–clavulanic acid (11.8 mg/kg [5.4 mg/lb], PO, q 12 h). Results of the bacterial culture identified 2 species of β-lactamase–negative bacteria and possible Peptostreptococcus spp. Therefore, the cat's antimicrobial treatment was changed from amoxicillin–clavulanic acid to clindamycin (12.7 mg/kg [5.8 mg/lb], PO, q 12 h). In addition, treatment with gabapentin (6.6 mg/kg [3.0 mg/lb], PO, q 8 to 12 h as needed) was initiated, combined with a tapering dosage of prednisolone (0.56 mg/kg [0.25 mg/lb], PO, q 24 h for 3 days followed by 0.28 mg/kg [0.13 mg/lb], PO, q 24 h for 3 days). On recheck ultrasonographic examinations of the cat's neck at 1 and 2 months after the initial referral examination, a progressive decrease in abscess size was noted. In addition, at the 2-month recheck examination, the cat did not have abnormal clinical signs, and all medications were discontinued. On recheck ultrasonographic examinations at 3 and 4 months after the initial referral examination, the abscess had resolved, with only a small hyperechoic region remaining in the soft tissues of the neck. This hyperechoic region was believed to have been focal fibrosis.
Comments
Retroesophageal abscesses are uncommon in domestic animals and people. Infections that migrate into the deep tissues of the neck can occur by 3 mechanisms: hematogenous, lymphogenous, and direct continuity (travel through fascial planes, such as secondary to esophageal foreign body penetration).1 The cause of the abscess in the cat of the present report was unknown, but was probably unrelated to the cat's history of head trauma prior to signs of cervical pain and change in behavior. The abscess was most likely caused by an esophageal perforation that occurred without immediate clinical signs but that led to the development of an abscess over time. However, it was conceivable that the traumatic event witnessed by the owners was the result of difficulty ambulating secondary to the preexisting abscess, rather than the cause of the abscess.
Radiography was chosen as the initial mode of diagnostic imaging to rule out any obvious bone lesions in the cat of the present report. Although the fluid-filled center of the abscess was not identified owing to the inherent inability of radiography to distinguish soft tissue from fluid, the homogeneous soft tissue swelling ventral to the cervical vertebrae was identified. Given the concern for spinal cord or nerve involvement, MRI, instead of ultrasonography, was chosen as the next diagnostic imaging modality. On MRI, a large mass with imaging characteristics consistent with an abscess and adjacent cellulitis2,3 was identified in the soft tissues, and there was no evidence of involvement of the spinal cord or nerves to explain the right thoracic limb hopping deficit noted on physical examination. Thus, the deficit was believed to have been caused by pain, which was consistent with the cat's history of reluctance to move. On ultrasonographic examination, paraesophageal abscesses appear as variably sized mass lesions that typically contain echogenic fluid and are often bordered by hyperechoic fat,4 as was observed in the cat of the present report.
Results of cytologic examination and bacterial culture of fluid aspirated from the lesion confirmed that it was, as suspected on the basis of MRI and ultrasonographic findings, an abscess. The potential Peptostreptococcus spp cultured were consistent with Peptostreptococcus anaerobius, a common oropharyngeal commensal isolated from cats and often isolated from abscesses resulting from cat bites.5 The bacterium has also been implicated in other infections, including meningoencephalitis, in cats.6 Therefore, an esophageal perforation could have allowed this commensal organism of the mouth and pharyngeal region to gain access to the retropharyngeal tissues and result in focal infection and abscessation.
The abscess in the cat of the present report resolved with ultrasonographically guided drainage and antimicrobial treatment. Similarly, successful medical management of a paraesophageal abscess has been reported in another cat.7 However, depending on clinical signs, location of the abscess, and presence of intralesional foreign material and other factors, surgical intervention may be indicated for treatment of retropharyngeal abscesses in veterinary patients.8
References
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3. Vansteenkiste DP, Lee KC, Lamb CR. Computed tomographic findings in 44 dogs and 10 cats with grass seed foreign bodies. J Small Anim Pract 2014;55:579–584.
4. Zwingenberger A, Taeymans O. Neck. In: Penninck D, d'Anjou MA, eds. Atlas of small animal ultrasonography. 2nd ed. Ames, Iowa: Wiley Blackwell, 2015;55–80.
5. Love DN, Vekselstein R, Collings S. The obligate and facultatively anaerobic bacterial flora of the normal feline gingival margin. Vet Microbiol 1990;22:267–275.
6. Dow SW, LeCouteur RA, Henik RA, et al. Central nervous system infection associated with anaerobic bacteria in two dogs and two cats. J Vet Intern Med 1988;2:171–176.
7. Jung J, Choi M. Nonsurgical resolution of caudal mediastinal paraesophageal abscess in a cat. J Vet Med Sci 2015;77:499–502.
8. Brissot HN, Burton CA, Doyle RS, et al. Caudal mediastinal paraesophageal abscesses in 7 dogs. Vet Surg 2012;41:286–291.
