Case Of the Month

Histiocytic sarcoma diagnosed by Tru-cut biopsy of thoracic mass in a 7-year-old FS Bernese Mountain Dog: Our Case Of the Month April 2015

A 7-year-old Bernese Mountain Dog (BMD) was presented for a history of persistent weight loss. The only abnormality on physical examination was a thin body condition. CBC and blood chemistry showed monocytosis, elevated creatinine, hypercalcemia, and mild hyperamylasemia. Survey thoracic radiographs showed a 4cm diameter spherical soft tissue opacity mass arising at the ventral tip of the lung to the right of the cardiac apex within the right middle lung lobe. There was also a 14cm x 6cm x 8cm mass infiltrating the ventral portion of the caudal subsegment of the left cranial lung lobe.

DX

Thoracic histiocytic sarcoma.

Outcome

Consultation with an oncologist was recommended but declined by the owner. The patient clinically declined and was humanely euthanized.

Comments

Core biopsy of lung masses is a safe procedure as long as the sonographer has a solid window to sample and is able to follow the needle in a clear direct path into the pathology with adequate distance for the need to discharge wihtin the lesion as we see here in this case. Post procedural pain meds are recommended since intercostal approaches tend to be more painful to the patient but very useful for the sonographer. Common etiologies of hypercalcemia include humoral hypercalcemia of malignancy (HHM), hypoadrenocorticism, chronic kidney disease, hypervitaminosis D, and primary hyperparathyroidism. Less common etiologies include bone neoplasia, osteomyelitis, hypertrophic osteodystrophy, granulomatous disease, calcium supplementation, and oral phosphate binders.

Clinical Differential Diagnosis

Malignant histiocytic sarcoma, metastatic pulmonary neoplasia, fungal granulomas, granulomatous disease.

Sampling

US-guided Tru-cut biopsy of the thoracic mass.

Sonographic Differential Diagnosis

This study shows lung consolidation and a mass with lack of detail. Primary lung neoplasia is likely. Sarcoma is most likely due to uniform hypoechoic presentation, but carcinoma or secondary lung metastasis are also possible. Lung necrosis with or without lung lobe torsion is considered less likely.

Image Interpretation

A uniformly marginated and consolidated lung mass is evident. The thin curvilinear hyperechoic line is consistent with pleura containing the lung pathology. Complete loss of lung infrastructure is noted. The hyperechoic linear focus represents the 16-gauge core biopsy needle.