Tumours of the musculoskeletal system

Nicholas J. Bacon

doi:10.22233/9781910443286.11

British Small Animal Veterinary Association , 154 (2018); https://doi.org/10.22233/9781910443286.11

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Tumours of the musculoskeletal system

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Author: Nicholas J. Bacon
From: BSAVA Manual of Canine and Feline Musculoskeletal Disorders
Item: Chapter 11, pp 154 - 166
DOI: 10.22233/9781910443286.11
Copyright: © 2018 British Small Animal Veterinary Association
Publication Date: November 2018

Abstract

To achieve the optimal outcome in cancer patients, an appreciation of the underlying natural history, biology, response to treatment and prognostic factors is required. Tumours of the musculoskeletal system are predominantly malignant sarcomas. This chapter covers primary tumours of bone, secondary/metastatic tumours of bone and tumours of soft tissues.

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Figures

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11.2

(a) A primary bone tumour of the distal radial metaphysis. Medullary lysis, sclerosis, cortical thinning, periosteal lifting (forming Codman’s triangle) and soft tissue swelling are all apparent. This was confirmed as an osteosarcoma. (b) A permeative lytic pattern of destruction is seen in the proximal humerus with areas of spiculated mineralization extending into the soft tissues. This has hallmarks of being a very aggressive osteosarcoma. © 2018 British Small Animal Veterinary Association

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11.2 (a) A primary bone tumour of the distal radial metaphysis. Medullary lysis, sclerosis, cortical thinning, periosteal lifting (forming Codman’s triangle) and soft tissue swelling are all apparent. This was confirmed as an osteosarcoma. (b) A permeative lytic pattern of destruction is seen in the proximal humerus with areas of spiculated mineralization extending into the soft tissues. This has hallmarks of being a very aggressive osteosarcoma.

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11.3

Pathological fracture of the right tibia in a Greyhound secondary to osteosarcoma. A lytic defect can be seen in the cranial cortex from which the fracture lines are originating. © 2018 British Small Animal Veterinary Association

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11.3 Pathological fracture of the right tibia in a Greyhound secondary to osteosarcoma. A lytic defect can be seen in the cranial cortex from which the fracture lines are originating.

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11.4

Dorsal plane CT image showing an osteosarcoma originating in the seventh rib, with minimal external change, but causing significant clinical signs due to compression of thoracic structures. This mass was successfully removed allowing function to return to normal. A = displaced heart; B = rib mass; C = liver. © 2018 British Small Animal Veterinary Association

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11.4 Dorsal plane CT image showing an osteosarcoma originating in the seventh rib, with minimal external change, but causing significant clinical signs due to compression of thoracic structures. This mass was successfully removed allowing function to return to normal. A = displaced heart; B = rib mass; C = liver.

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11.5

Osteosarcoma of the ischium (arrowed) causing the dog to present with pelvic limb lameness. In this case, a hemipelvectomy was performed including an osteotomy at the mid ilial body, and pubic osteotomies cranial and caudal to mid obturator foramen. © 2018 British Small Animal Veterinary Association

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11.5 Osteosarcoma of the ischium (arrowed) causing the dog to present with pelvic limb lameness. In this case, a hemipelvectomy was performed including an osteotomy at the mid ilial body, and pubic osteotomies cranial and caudal to mid obturator foramen.

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11.6

Osteosarcoma of the left scapula. (a) The cranial–caudal view is the more useful as (b) the lateral view has many superimposed structures, such as the opposite scapula and the cervical/thoracic spine, making determination of the tumour margins difficult. CT will better define the extent of disease and help plan the required osteotomy to remove the proximal scapula if a limb-sparing surgery is intended. © 2018 British Small Animal Veterinary Association

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11.6 Osteosarcoma of the left scapula. (a) The cranial–caudal view is the more useful as (b) the lateral view has many superimposed structures, such as the opposite scapula and the cervical/thoracic spine, making determination of the tumour margins difficult. CT will better define the extent of disease and help plan the required osteotomy to remove the proximal scapula if a limb-sparing surgery is intended.

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11.8

(a) A technetium bone scan in a Greyhound with a distal femoral osteosarcoma which showed unexpected uptake in the right humeral diaphysis (arrowed). (b) A radiograph confirmed the presence of a bone lesion at this site, subsequently confirmed to be osseous metastasis (arrowed). © 2018 British Small Animal Veterinary Association

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11.8 (a) A technetium bone scan in a Greyhound with a distal femoral osteosarcoma which showed unexpected uptake in the right humeral diaphysis (arrowed). (b) A radiograph confirmed the presence of a bone lesion at this site, subsequently confirmed to be osseous metastasis (arrowed).

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11.9

(a) Discrete distal ulnar osteosarcoma. (b) Immediately post partial ulnectomy; approximately the distal 50% of the ulna has been removed (the metal artefacts are skin staples). The limb is supported with a dressing for 10 days. The dog should be walking the day after surgery, with an excellent return to function expected. © 2018 British Small Animal Veterinary Association

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11.9 (a) Discrete distal ulnar osteosarcoma. (b) Immediately post partial ulnectomy; approximately the distal 50% of the ulna has been removed (the metal artefacts are skin staples). The limb is supported with a dressing for 10 days. The dog should be walking the day after surgery, with an excellent return to function expected.

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11.10

(a) The distal radius including the tumour is removed en bloc with the intimately attached distal ulna. The osteotomy is made 3 cm proximal to the radiographically and visibly abnormal bone. (b) The large tissue defect is evident between the ostectomized ends of the radius and ulna (left) and the proximal row of carpal bones (right). (c) A metal endoprosthesis is inserted into the defect and held in position with screws into the radius and third metacarpal bone. This effectively fuses the carpus in position, although a true arthrodesis is not expected to form as the carpal cartilage is not debrided, and a bone graft is not placed. © 2018 British Small Animal Veterinary Association

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11.10 (a) The distal radius including the tumour is removed en bloc with the intimately attached distal ulna. The osteotomy is made 3 cm proximal to the radiographically and visibly abnormal bone. (b) The large tissue defect is evident between the ostectomized ends of the radius and ulna (left) and the proximal row of carpal bones (right). (c) A metal endoprosthesis is inserted into the defect and held in position with screws into the radius and third metacarpal bone. This effectively fuses the carpus in position, although a true arthrodesis is not expected to form as the carpal cartilage is not debrided, and a bone graft is not placed.

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11.11

This Mastiff has undergone stereotactic radiosurgery for a distal radius osteosarcoma to sterilize the tumour. A bone plate has been applied to minimize the risks of post-radiation pathological fracture. The lytic bone in the radius and pre-existing ulnar pathological fracture can be seen beneath the bone plate. © 2018 British Small Animal Veterinary Association

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11.11 This Mastiff has undergone stereotactic radiosurgery for a distal radius osteosarcoma to sterilize the tumour. A bone plate has been applied to minimize the risks of post-radiation pathological fracture. The lytic bone in the radius and pre-existing ulnar pathological fracture can be seen beneath the bone plate.

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11.12

The pink sessile fleshy mass just rostral to the second right premolar (arrowed) is tumour recurrence following incomplete excision of a mandibular osteosarcoma. © 2018 British Small Animal Veterinary Association

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11.12 The pink sessile fleshy mass just rostral to the second right premolar (arrowed) is tumour recurrence following incomplete excision of a mandibular osteosarcoma.

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11.13

An intraoperative view of a chest wall resection for a rib osteosarcoma (A). Caudal is to the left; ventral at the top. The internal thoracic vessels can be seen running from caudal to cranial along the length of the surgical field (arrowed). © 2018 British Small Animal Veterinary Association

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11.13 An intraoperative view of a chest wall resection for a rib osteosarcoma (A). Caudal is to the left; ventral at the top. The internal thoracic vessels can be seen running from caudal to cranial along the length of the surgical field (arrowed).

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11.14

Osteosarcoma of the seventh lumbar vertebra in a dog assumed to have hindlimb weakness and stiffness due to non-neoplastic degenerative orthopaedic and neurological disease. Note the patchy ill defined lysis of the vertebral body of L7, with irregular poorly defined new bone along the ventral aspect and caudal endplate. © 2018 British Small Animal Veterinary Association

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11.14 Osteosarcoma of the seventh lumbar vertebra in a dog assumed to have hindlimb weakness and stiffness due to non-neoplastic degenerative orthopaedic and neurological disease. Note the patchy ill defined lysis of the vertebral body of L7, with irregular poorly defined new bone along the ventral aspect and caudal endplate.

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11.15

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11.15 Pathological fracture of the femur secondary to diffuse bone lysis evident throughout the bone in a dog with multiple myeloma.

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11.16

Dorsal plane post-contrast CT image of an appendicular haemangiosarcoma in the proximal femur of a German Shepherd Dog, with the soft tissue vascular component expanding along the ilium and into the obturator foramen (arrowed). This dog was treated with a hemipelvectomy, disarticulating the sacro-iliac joint and performing a midline pubic osteotomy. © 2018 British Small Animal Veterinary Association

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11.16 Dorsal plane post-contrast CT image of an appendicular haemangiosarcoma in the proximal femur of a German Shepherd Dog, with the soft tissue vascular component expanding along the ilium and into the obturator foramen (arrowed). This dog was treated with a hemipelvectomy, disarticulating the sacro-iliac joint and performing a midline pubic osteotomy.

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11.17

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11.17 Classic appearance of a fixed multilobular tumour of bone on the calvarium of a dog.

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11.18

Radiograph showing a predominantly proliferative bone disease in the distal femoral diaphysis. Ultrasound-guided fine-needle aspirates from the area yielded malignant epithelial cells, later confirmed to be metastatic transitional cell carcinoma from the prostate. © 2018 British Small Animal Veterinary Association

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11.18 Radiograph showing a predominantly proliferative bone disease in the distal femoral diaphysis. Ultrasound-guided fine-needle aspirates from the area yielded malignant epithelial cells, later confirmed to be metastatic transitional cell carcinoma from the prostate.

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11.19

This dog presented with non-specific head pain and left-sided temporal swelling. Radiographs confirmed this was soft tissue swelling with no osseous reaction, later confirmed to be an intramuscular haemangiosarcoma of the temporal muscle. © 2018 British Small Animal Veterinary Association

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11.19 This dog presented with non-specific head pain and left-sided temporal swelling. Radiographs confirmed this was soft tissue swelling with no osseous reaction, later confirmed to be an intramuscular haemangiosarcoma of the temporal muscle.