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  • A 10-year-old female spayed pit-bull mix presented for progressive left thoracic limb lameness of approximately 2.5 months duration, without known trauma.
  • The patient is currently having difficulty walking, has edema in both front limbs, and has decreased muscle mass.
  • The owners report lethargy and weakness.
  • Gabapentin and carprofen help with perceived pain but not lameness.
  • The patient has no travel history (lives in Oregon) and has no known comorbidities.

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Dorsal CT still image

Imaging Findings:

  • Centered at and causing severe permeative osteolysis of the caudal cortex of the left first rib is a severely large (1.4 x 9.9 x 10.4), lobular, heterogeneously enhancing mass with stippled mineralization.
  • This mass extends both intra and extrathoracic, causing the following: right dorsolateral deviation of trachea, compression of cranial vena cava, right ventrolateral displacement of the left axillary artery, lateral displacement of left axillary lymph node.
  • Adjacent ribs (2nd-4th) have mixed periosteal response and osteolysis (2nd rib only).
  • Left caudal lung lobe has a medium (1.3cm) peripherally well-defined nodule with mild mineralization. Coursing from this nodule craniolaterally along the bronchovascular bundle is a medium soft tissue tubular structure which causes focal widening of the pulmonary vein, mild attenuation of the bronchial lumen, and tapers abruptly.
  • Multiple lymph nodes are bilaterally enlarged, rounded, and heterogeneously enhancing: superficial cervical (2.2cm), axillary (1cm), accessory axillary (0.8cm), and sternal (1.5cm).
  • Ventrally, the subcutaneous fat and thoracic wall musculature has numerous soft tissue wisps causing reduced margin definition of the fascial fat and muscular margins. The left-sided thoracic limb and body wall musculature is moderately small and decreased in attenuation.

Summarized imaging diagnosis:

  • Left thoracic limb lameness is attributed to the extensive left thoracic body wall mass with polyostotic aggressive bone lesions (left 1-4 ribs)
  • A single metastatic pulmonary nodule with pulmonary venous invasion, and moderate regional lymphadenopathy, likely neoplastic.
  • The primary differential is malignant neoplasia (e.g. histiocytic sarcoma, soft tissue sarcoma, or hemangiosarcoma; primary osseous neoplasia is less likely).
  • Moderate, secondary left thoracic limb and body wall muscle atrophy with regional dependent edema (vascular compression, lymphedema) 3.

Conclusions:

  • FNA of the thoracic wall mass was cytologically consistent with sarcoma, with evidence of chronic and ongoing hemorrhage.
    • Pathology comments considered hemangiosarcoma the primary differential due to cellular features in combination with marked evidence of hemorrhage. Lesser considerations were atypical histiocytic sarcoma as well as other sarcomas with secondary hemorrhage.
  • Hemangiosarcoma is an uncommonly described primary bone tumor in dogs.
    • In a retrospective study of 22 dogs with osseous hemangiosarcoma, the most commonly affected bones were proximal humerus and ribs, causing pain, lameness, and soft tissue swelling (Bingel et al 1974).
    • Additionally, hemangiosarcoma has been described in a study of primary rib tumors (3/54; Pirkey-Ehrhart et al 1995) and in small numbers as scapular tumors (n=3; Erdem and Pead 2000) (2/42; Montinaro et al 2013).
    • Additional case reports document hemangiosarcoma in the proximal humerus in Maltese (Hidaka 2006), proximal humerus of a Collie (Childers 1970), proximal tibia in a Doberman (Petterino et al 2013), and in the digit of a Huskie (Moon et al 2020).

References:

  • Bingel et al. Haemangiosarcoma of bone in the dog. JSAP 1974.
  • Pinkey-Ehrhart. Primary rib tumors in 54 dogs. JAAHA 1995.
  • Erdem V, Pead MJ. Haemangiosarcoa of the scapula in three dogs. JSAP 2000.
  • Montinaro et al. Clinical outcome of 42 dogs with scapular tumors treated by scapulectomy: a veterinary society of surgical oncology (VSSO) retrospective study (1995-2010). Vet Surg 2013.
  • Hidaka et al. Primary hemangiosarcoma of the humerus in a Maltese dog. J Vet Med Sci 2006. Childers. What’s your diagnosis. JAVMA 1970.
  • Pettino et al. Primary haemangiosarcoma of the tibia in a dog: clinical and pathological findings. Comp Clin Pathol 2014. Moon et al. Primary bone hemangiosarcoma involving the 4th digit in a Siberian Husky. Vet Record 2020.