Ectopic Intrathoracic Hepatic Tissue and Accessory Lung Lobe Aplasia in a Dog

Abstract

A 6 yr old male Yorkshire terrier was presented for an ~6 yr history of progressive cough and dyspnea. Thoracic radiographs revealed a 6 cm diameter mass within the right caudal thorax. Thoracic ultrasound identified an intrathoracic mass ultrasonographically consistent with liver tissue and a chronic diaphragmatic hernia was suspected. Exploratory laparotomy was performed, but no evidence of a diaphragmatic hernia was identified. Thoracic exploration identified abnormal lung parenchyma. The accessory lung lobe was removed using a stapling devise near its base. The consolidated mass had the gross appearance of liver and was histologically identified as ectopic hepatic tissue. Ectopic hepatic tissue, unlike ectopic splenic and pancreatic tissue, is rare and generally has a subdiaphragmatic distribution. This solitary case report demonstrates that ectopic intrathoracic hepatic tissue should be considered a differential diagnosis for a caudal mediastinal mass.

Anatomical considerations for the surgical approach to the canine accessory lung lobe

“…• The lateral extension (10): an extension of the dorsal process lying ventrolaterally to the bronchus (9) and artery of the ALL (11). • The medial extension (12): an extension from the region where the right lateral and ventral processes converge cranially, lying ventromedially to the bronchus and associated with the medial vein (from the ventral process of the ALLsee below).…”

“…Of the few reported cases of accessory lung lobectomy in the literature, both median sternotomy and lateral thoracotomy approaches have been described. [10][11][12] To the authors' knowledge, access via left lateral thoracotomy has not been reported or performed. Despite the valid anatomical reasons for this, documenting this approach may be useful to illustrate relevant surgical anatomy given the lobe's central location within the thorax.…”

“…Surgical approaches to cranial and caudal lung lobes in dogs are well described in surgery textbooks and the veterinary literature; however, no specific description exists for the accessory lung lobe. [5][6][7][8][9] Studies have shown that pathologies can be limited to this lung lobe, [10][11][12][13] so specific anatomical considerations that affect access to this lung lobe need to be considered. Of the few reported cases of accessory lung lobectomy in the literature, both median sternotomy and lateral thoracotomy approaches have been described.…”

“…Studies have shown that pathologies can be limited to this lung lobe, 10–13 so specific anatomical considerations that affect access to this lung lobe need to be considered. Of the few reported cases of accessory lung lobectomy in the literature, both median sternotomy and lateral thoracotomy approaches have been described 10–12 . To the authors' knowledge, access via left lateral thoracotomy has not been reported or performed.…”

Caval foramen hernia in a dog: Preoperative diagnosis and surgical treatment

“…However, some authors suggest non-imperative surgery because benign diagnoses have recently become more common owing to an increase in incidentally found ELs [3,12]. As the herniated liver tissue in a CFH is part of the continued liver but just displaced, 4) it always appears in contact with the diaphragm, while intrathoracic ELs could be found elsewhere in the thoracic cavity as a mediastinal, pleural, intrapericardial, or intrapulmonary mass [1,7,10,12]. In this case, hepatic tissue was herniated through a caval foramen ventral to the CVC, maintaining its definitive running vessels inside.…”