Minimally invasive cranial mediastinal mass extirpation

Indications for cranial mediastinal mass excision

Cranial mediastinal neoplasia is relatively uncommon in dogs. However, when observed, the most likely diagnoses are lymphoma, thymoma and less commonly thymic carcinoma. Other neoplasms of the cranial mediastinum have also been described. Dogs with thymic lymphoma are managed medically whereas dogs with other neoplasms such as thymoma are treated surgically. Traditionally, resection of cranial mediastinal masses has been accomplished via median sternotomy or intercostal thoracotomy. Recently, a VATS approach to cranial mediastinal mass resection in two dogs was reported [Mayhew & Friedberg 2008]. A VATS approach to cranial mediastinal mass (CMM) resection is feasible and associated with low operativerelated morbidity although ultimate prognosis is dependent on the underlying disease [MacIver et al. 2015]. For example, dogs with Myasthenia Gravis (MG) and megaesophagus have a poor short-term outcome despite successful open or VATS CMM resection [MacIver et al. 2015, Atwater et al. 1994].

Patient preparation/selection

Dogs with MG and megaesophagus appear to have a poor prognosis even after successful thymectomy and owners should be made aware of this prior to surgery [MacIver et al. 2015, Atwater et al. 1994]. Dogs with large and invasive CMM are not candidates for a VATS CMM extirpation. Thus, preoperative computed tomography is strongly advised to determine if a patient is a candidate for a VATS resection. Dogs > 20 kg with noninvasive masses and with a diameter < 7 cm or an approximate volume less than 300 cm³ , appear to be reasonable candidates for a VATS CMM resection [MacIver et al. 2015]. [...]