Primary pulmonary histiocytic sarcoma with nodal and esophageal metastasis in a dog—imaging and anatomopathological aspects

Abstract

BackgroundThis report presents a case of esophageal and nodal metastasis in a primary pulmonary histiocytic sarcoma in a dog. Histiocytic sarcoma is a malignant neoplasm originating from histiocytic cells, characterized by its aggressive nature, high metastatic potential and high mortality rate. Pulmonary involvement occasionally results in pleural effusion and regional lymph node involvement, such as the tracheobronchial, sternal, and mediastinal lymph nodes. Thoracic radiography is the preferred complementary diagnostic test when respiratory disorders are suspected, as it can identify pulmonary masses and associated complications, such as pleural effusion. Similarly, ultrasonography can be used when pulmonary conditions are suspected, helping to differentiate lesions.Case presentationA one-year-old, intact male mixed-breed dog weighing 18 kg was referred for emergency clinical care due to severe inspiratory dyspnea. Thoracic radiography and ultrasonography revealed a large intrathoracic mass located in the mediastinum, displacing adjacent structures, along with associated pleural effusion. The primary diagnostic hypothesis was a neoplasm of cranial mediastinal origin. During the thoracocentesis procedure, the animal decompensated and died. Necropsy revealed a large, multilobulated tumor mass in the mediastinum, showing direct extension into the esophagus, as well as another nodule similar to the mediastinal mass in the left caudal lung lobe. Histopathological analysis supported the diagnosis of pulmonary histiocytic sarcoma with esophageal and nodal metastasis, confirmed through an immunohistochemical panel.ConclusionsThe involvement of cranial mediastinal and tracheobronchial lymph nodes, as well as the presence of pleural effusion, are common features associated with HS. However, the occurrence of esophageal metastases is considered uncommon, highlighting the uniqueness of this case, as well as supporting the potential for its occurrence. Thoracic radiography and ultrasonography played a crucial role in the initial suspicion of neoplasia, emphasizing their importance in early diagnostic approaches.