Clinical Case Challenge

Cranial Mediastinal Mass in an Old Dog

History: An 11 year-old, spayed female Labrador retriever presents for polyuria and polydipsia.  The owners report mild lethargy but the dog is otherwise doing well.  Physical examination reveals body condition 4/9 but is otherwise within normal limits for a dog of this age. A complete blood count is within normal limits.  The chemistry profile reveals total calcium 15.4 mg/dl (NR,  9.4-11.8), ionized calcium 1.7 mmol/L (NR, 1.12-1.40), creatinine  2.1 mg/dl (NR, 0.6-2.0), BUN 39 mg/dl (NR, 8-30).  Urinalysis reveals dilute urine with a specific gravity of 1.008.   Thoracic radiographs are taken (Figure 1) and an ultrasound-guided fine needle aspiration is performed..

Figure 1: Lateral thoracic radiograph demonstrating cranial mediastinal mass.

What are the differential diagnoses for this lesion?

Figure 2: Cytology of cranial mediastinal mass. Green arrows point to mast cells.

What is your diagnosis?  How would you treat this dog? Continue reading

At Your Service

Tufts’ Clinical Oncology Team

The clinical oncology service is comprised of veterinary oncologists, residents and technicians that work together as a team.  The oncology service works closely with the surgery service, which has expertise in surgical oncology, as well as with pathology, diagnostic imaging, interventional radiology, and the pain clinic.  Through the collaboration with these and other specialty services throughout the hospital, we are able to offer a broad range of options for owners of companion animals with cancer.

As a member of the National Cancer institute’s Comparative Oncology Trials Consortium, as well as through independent studies and collaboration with other veterinary and biomedical institutions, the oncology service is able to offer investigational therapies in addition to conventional treatment.

The oncology service boasts a 6 MV Siemens linear accelerator with 2-16 MeV electrons, a multileaf collimator, and intensity-modulated radiation therapy (IMRT) capabilities.  In addition, strontium 90 plesiotherapy is offered, allowing for wide breadth of radiation therapy options. Continue reading

Innovation

High-Dose Cyclophosphamide Holds Promise for Dogs with Lymphoma

For decades, the cornerstone of treatment for dogs with lymphoma has been chemotherapy employing five drugs: cyclophosphamide, doxorubicin, vincristine, L-asparaginase and prednisone.  Efforts to optimize these protocols by adjusting the doses and scheduling of drugs have not yielded significant improvement in remission rates or survival times.  In addition, the realization that discontinuous short chemotherapy protocols are as effective as traditional long protocols that include a lengthy maintenance phase has provided the opportunity to search for novel therapies to combat lymphoma before overt chemotherapy resistance develops.

Alternative modalities that have been studied include radiation therapy, chemotherapy agents traditionally reserved for rescue therapy, monoclonal antibodies, dose-intensified chemotherapy and bone marrow transplantation.  These approaches have yielded variable results, and some promising findings are under continued investigation. Continue reading