Download - Mediastinal cysts
MEDIASTINAL CYSTSJames Montgomery, DVMNovember 3, 2008
Mediastinal cysts
Infrequently occur Congenital or idiopathic Origin:
Pleural Branchial Parathyroid Thyroglossal Lymphatic Bronchogenic Thymic
Clinical signs
Generally none
Respiratory difficulty Space occupying
Patient ID: 132472
Allie 9 year old Spayed female Domestic shorthair
Weight loss, lethargy
Radiographs - 106076
Radiographs - 106076
Radiographs - 106076
Differential diagnoses
Abscess Granuloma Lymphadenopathy Hematoma Ectopic thyroid tissue Cyst Neoplasia
Lymphosarcoma, thymoma
Ultrasound - 106086
Ultrasound - 106086
Ultrasound - 106086
Aspirated 8mL golden brown fluid Cytology: WBC=200/ul; Protein=0.3 g/dl.
Extremely low cellularity. Contains only rare erythrocytes and debris.
No etiologic agents observed Interpretation: Low cellularity, low protein
fluid.
Consistent with idiopathic mediastinal cyst
Treatment options
In the absence of respiratory signs, intervention is not warranted (Zekas LJ, Adams WM. Vet Radiol Ultrasound 2002;43:413-8) Generally considered an incidental finding
Surgical removal Functional cysts (parathyroid) Space-occupying disease
Tracheal or vascular compression
Differentiating cysts
Histologic evaluation needed
Clinical findings: Thymic branchial cysts
Dyspnea, pleural effusion, aspiration of mucinous fluid
Multicystic appearance Thymic branchial cysts Lymphangiomas Cystic thymomas
Embryology
4 embryologic pharyngeal pouches Abnormal development may lead to formation
of cystic structures in the neck and cranial mediastinum
1st – Eustachian tube (middle ear) 2nd – Supratonsillar fossa
Branchial cysts 3rd – Thymus and cranial parathyroid glands 4th – Caudal parathyroid glands &
contributes to thyroid gland formation Thyroglossal cysts – abnormal development
near site of origin of the thyroid diverticulum
Summary
Opacities in the cranial mediastinum on thoracic radiographs should be investigated
Ultrasonographic identification of an anechoic mass with clear fluid supports diagnosis of mediastinal cyst
Majority of feline cranial mediastinal cysts are benign with no need for treatment
References
Ellison GW, et al. Idiopathic mediastinal cyst in a cat. Vet Radiol Ultrasound 1994;35:347-9.
Moore LE, Biller DS. Mediastinal disease. In Ettinger SJ, Feldman EC, eds. Textbook of Veterinary Internal Medicine, 6th ed (St. Louis, MO: Elsevier Saunders, 2005) pp. 1268-9.
Swainson SW, et al. Radiographic diagnosis: mediastinal parathyroid cyst in a cat. Vet Radiol Ultrasound 2000;41:41-3.
Zekas LJ, Adams WM. Cranial mediastinal cysts in nine cats. Vet Radiol Ultrasound 2002;43:413-8.