Whole Body Computed Tomographic Characteristics of Skeletal and Cardiac Muscular Metastatic Neoplasia in Dogs and Cats

Abstract

Muscular metastatic neoplasia has been reported to be rare in domestic animals, however previous studies were based primarily on necropsy findings. The purpose of this retrospective study was to describe whole body computed tomography (CT) characteristics of confirmed muscular metastases in a cohort of dogs and cats presented for oncology evaluation. Medical records of 1201 oncology patients were reviewed. Included animals underwent pre and postcontrast whole body CT, and CT-guided tru-cut biopsy or fine needle aspiration of one or more metastatic lesions. Twenty-one dogs and six cats met inclusion criteria, representing 2.08% of all canine oncology patients and 3.1% of all feline oncology patients. Mean age was 9.6 years. Postcontrast CT characteristics included well-demarcated, oval-to-round lesions with varying enhancement patterns: ring enhancing (n = 16), heterogeneously enhancing (n = 8), or homogeneously enhancing (n = 5). Five animals showed concurrent and varying nodular patterns. In seven cases (five dogs and two cats), one single muscular nodule was observed. In 20 cases, two or more lesions were observed. In two cases, cardiac hypodense nodules were observed in the postcontrast CT, while appearing isodense in the precontrast study. Necropsy confirmed neoplasia in both of them. Locations of muscular metastases included epaxial/paraspinal muscles of the cervical, thoracic, and lumbar spine (n = 18), superficial muscles of the thoracic wall (n = 13), scapular/shoulder region (n = 3), hind limb (n = 3), and abdominal wall muscles (n = 1). Findings supported the use of pre and postcontrast whole body CT for oncologic staging in dogs and cats, especially for primary tumors characterized by a high metastatic rate.

Imaging Diagnosis—ultrasonographic Appearance of Skeletal Muscle Metastases in a Dog With Hemangiosarcoma

“…Ultrasonographic patterns of skeletal muscle metastases should be further explored, as this information may carry important prognostic information for the patient. Metastases to the muscle seem to be a late manifestation of advanced disease, in people as well as in animals . In small animals, the median survival time for patients with muscular metastases has been reported in a study to be 15 days for dogs and 14 days for cats …”

“…Skeletal muscle metastases are considered a rare event, in both people and animals . In veterinary patients, muscular metastases have been mainly diagnosed based on necropsy, biopsy, or CT, but reports describing ultrasonographic features of these lesions are lacking.…”

“…Skeletal muscle metastases are considered a rare event, in both people and animals . In veterinary patients, muscular metastases have been mainly diagnosed based on necropsy, biopsy, or CT, but reports describing ultrasonographic features of these lesions are lacking. Primary tumors associated with muscular metastasis include carcinoma (pulmonary, mammary, and prostatic), lymphoma, and mast cell tumors .…”

“…Primary tumors associated with muscular metastasis include carcinoma (pulmonary, mammary, and prostatic), lymphoma, and mast cell tumors . Sarcomas were highly represented in a cohort of dogs and cats in a recent study, HSA being the most common subtype . Locations of muscle metastases include epaxial/paraspinal muscles of the spine, limb muscles, superficial muscles of the thoracic and abdominal walls and scapular/shoulder region muscles …”

“…Although the use of the whole body CT is highly recommended in the staging of oncologic veterinary patients, conventional radiology and ultrasonography remain the most common imaging modalities used in routine clinical practice in veterinary medicine . Muscle ultrasound is particularly demanding, as high‐frequency transducers and accurate placement of the transducers are needed to obtain diagnostic images.…”