Written by Sofia Carvalho, DVM, MVetMed, DipACVIM (Oncology), MRCVS. and Francesco Rogato, DVM, MRCVS.
Winnie, a five-year old domestic shorthair cat presented to our practice in mid-March 2019 for further investigations of progressive onset of lethargy and breathing difficulties. Thoracic radiographs performed at her referring veterinary practice had revealed the presence of a large mediastinal mass (see radiograph below).
The right lateral thoracic view at time of diagnosis.
On presentation Winnie was dull but responsive. Her heart rate was 180 beats per minute, with muffled cardiac and pulmonary sounds and her respiratory rate was 60 breaths per minute. No other significant abnormalities were identified on clinical examination.
Haematology and biochemistry profile showed no significant abnormalities, and retroviral testing for FIV and FeLV were negative.
Thoracic ultrasound revealed a large mediastinal mass and a mild to moderate amount of pleural effusion. A therapeutic pleurocentesis was performed and 30ml of serosanguineous fluid were drained. An echocardiography revealed a normal cardiac structure and function.
Ultrasound-guided fine needle aspirates of the mediastinal mass were performed. Cytology results revealed a dominant population of monomorphic intermediate sized lymphocytes, consistent with lymphoma. Flow cytometry results were consistent with a T-cell lymphoma.
Further staging procedures with advanced thoracic and abdominal imaging, and fine needle aspirates for staging purposes were not carried out at that time based on owner’s wishes, and as further procedures were unlikely to change Winnie’s treatment options and overall prognosis.
The decision was made to start Winnie’s treatment with a COP protocol. This consisted in weekly administrations of intravenous vincristine treatments for six weeks, alongside cyclophosphamide treatments to be given on weeks 2 and 4 of the protocol, and prednisolone.
One week following the start of the COP protocol Winnie had improved greatly, and her respiratory rate and effort had returned to almost normal. Winnie seemed to tolerate the chemotherapy treatments well, and during the following few weeks of the protocol Winnie was reported to be experiencing an excellent quality of life, and her owner didn’t have any concerns.
At the end of the six weeks of protocol staging was recommended to assess the progression of Winnie’s disease. At this time a more complete staging of Winnie’s lymphoma was performed.
Three view thoracic radiographs revealed a mid-ventral mediastinal mass (see radiograph below), which was markedly reduced in comparison with previous study at time of diagnosis of mediastinal lymphoma. This lesion was confirmed with thoracic ultrasound, which also revealed the presence of a minimal amount of pleural effusion. Unfortunately both of these lesions were deemed too small to be sampled, although we believe that most likely the mediastinal lesion and small amount of pleural effusion represent residual lymphoproliferative disease. Fine needle aspirates of liver and spleen were performed, and cytology results revealed no obvious evidence of lymphoma infiltration in these organs.
The left lateral thoracic view at the end of the six weeks COP protocol.
We were very pleased to note that Winnie’s staging results were overall consistent with a good partial remission of her lymphoma. Due to the likely presence of residual disease the COP protocol is currently being continued for three more weeks, and we are aiming to repeat thoracic imaging then to assess response to treatment, and plan continuation of Winnie’s treatment. We are hoping the continuation of the COP protocol will induce a complete remission of Winnie’s lymphoma, and Winnie will start receiving maintenance chemotherapy treatment soon.
Winnie’s owner is really pleased with Winnie’s overall progress, and reported that Winnie is behaving like a kitten again. Winnie is loving the start of the Spring and keeps enjoying her brother’s company.