Ch 31 Thoracic Wall Flashcards
What other condition is reported in some animals with congenital sternal abnormalities?
PPDH
What is pectus carinatum caused by?
Idiopathic overgrowth of costal cartilages
Pectus carinatum can be seen in connection with _______ and/or ________.
Congenital heart disease
Sternal segment absence
Pectus excavatum is largely congenital/acquired, in animals.
Congenital, possibly hereditary, and associated with respiratory and cardiovascular anomalies
What has been reported as an underlying cause of pectus excavatum in a dog and how was this treated?
Laryngeal paralysis > chronic inspiratory dyspnea
Tie-back (arytenoid lateralisation) > resolution of pectus excavatum
Which 3 factors support a diagnosis of rib fractures due to trauma (rather than an aggressive lesion)?
- history of trauma
- overriding rib margins
- involvement of multiple adjacent ribs
You can re-radiograph in 2 weeks; or FNA/biopsy.
What injury causes flail chest?
What kind of thoracic wall movement happens with flail chest?
Paradoxical movement
What is paradoxical movement of the thoracic wall?
Inward displacement during inspiration
Which ribs are most commonly fractures spontaneously in cats?
mid-portion of 9-13th
What is the cause and supporting factor of spontaneous rib fractures in asthmatic cats?
mechanical failure (secondary to chronic dyspnea or coughing)
osteopenia
What are 3 conditions that increase the risk for spontaneous rib fractures?
- disease that cause prolonged respiratory effort
- metabolic disease (renal failure)
- some neoplasms (e.g. metastatic plasma cell tumour)
What is the extrapleural sign?
What sign is this (arrow)?
Extrapleural sign
What direction of x-ray beam is preferential /necessary for an extrapleural sign to be visible?
tangential
What is the most common origin (tissue/organ) of the extrapleural sign?
Rib
If a lung mass is in contact with the thoracic wall, the angle between the mass and the wall will be:
(as opposed to an extrapleural mass)
90’ or less
Rib infection is common/rare.
What might cause a rib periostitis?
What might cause arib osteomyelitis?
Rare
Severe pyothorax
Mycotis septicaemia
Although differentiation between rib neoplasia and infection is not possible, what might hint at a neoplasia?
More soft tissue mass effect
Which is more common - rib neoplasia or rib infection?
Neoplasia
Primary rib tumours are of _____ origin, e.g. ____, ____
mesenchymal; osteosarcoma, chondrosarcoma
Why are primary rib tumours commonly diagnosed late?
Because of intrathoracic extension occuring to a greater extent than peripheral extension i.e. they are not obvious on the outside
What is a common secondary finding of advanced stage rib tumours?
Pleural effusion
If you see pleural effusion, what should you look for?
Rib tumours
Metastatic lesions to the ribs are often proliferative/lytic/
lytic, with varying degrees of periosteal reaction
Can a primary pulmonary tumour metastasise to the ribs?
Yes, rare, but has been reported - described in 2 cats; adenocarcinoma metastasis to ribs via involved pleura.
Sternebral tumours are of _____ origin.
Mesenchymal
Most neoplasias that alter the architecture of the sternebrae are _____
Soft tissue neoplasias of the thoracic wall that invade the bone
Possible origins of infections of the sternebrae
- bite wounds
- migrating foreign body e.g. grass seed > osteomyelitis
- hematogenous > endplate lysis and proliferation (similar to disco)
Soft tissue tumours of the thoracic wall are rare / common
Fairly common
What is the most common soft tissue tumor of the thoracic wall?
Benign lipomas
Fig. 31.32 A, Ventrodorsal (VD) thoracic radiograph of a dog. A large, fat opacity mass (lipoma) is present along the left lateral thoracic wall. This mass is infiltrating the left fifth intercostal musculature, resulting in splaying of the left fifth and sixth ribs.
Right lateral radiograph of a dog with a thoracic wall lipoma ventral to the sternum. Two smaller lipomas are also present in the subcutaneous tissues ventral to the caudal sternum (black arrow).
What type of tumor is associated with vaccination sites?
Fibrosarcoma
What is the most common cause of cellulitis and thoracic wall infection?
Trauma
Migrating grass awns
What is a reported rare complication of the thoracic wall following surgery (especially in GSD)?
Calcinosis circumscripta
Why is CT helpful for vaccine-associated fibrosarcomas?
Post-con CT will show infiltration (neoplastic +/- inflammatory) lesions into tissues that otherwise appear normal on pre-con.
“Postcontrast images often depict tendrils of inflammatory or neoplastic tissue dissecting through otherwise radiographically normal-appearing soft tissues”
