This 89 year old FS dog presented with a firm, nonpainful superficial ovoid mass of two weeks duration.
Physical Exam: subcutaneous vs within superficial muscle — left proximal, medial brachium (just distal to axilla).
This 89 year old FS dog presented with a firm, nonpainful superficial ovoid mass of two weeks duration.
Physical Exam: subcutaneous vs within superficial muscle — left proximal, medial brachium (just distal to axilla).
CT of the front limbs, plain and post contrast-
A well-delineated ovoid soft tissue mass of approximately 3.5 x 2 cm is seen within the
left armpit between the superficial pectoralis muscle and the brachial & biceps
muscles. The mass is superficial to the brachial artery and vein and distal to the
axillary nerve and vessel plexus. The axillary lymph node is seen and within normal
limits.
The mass is similar in attenuation and enhancement behaviour to the surrounding
musculature with a slightly hypoattenuating and non-enhancing center. An
inflammatory pattern is not noted.
A specific origin of the soft tissue mass cannot be determined. Mast cell tumor,
histiocytoma/histiocytic sarcoma/cutaneous lymphoma, fibroma, sarcoma (such as
fibrosarcoma, rhabdomyosarcoma, myxosarcoma, hemangiosarcoma), and other
neoplasias should be considered. An origin from a supernumerous lymph node or from
within the peripheral branches of the brachial plexus nerves cannot be ruled out but is
unlikely with the findings here. The findings are neither typical for an abscess nor for
lipoma/liposarcoma.
Depending on the results of the biopsy full tumor staging with 3 view chest
radiographs and ultrasound of the abdomen plus/minus cursory echocardiographic
examination to rule out pericardial effusion and/or heart base masses is recommended
prior to surgery. Critical structures to consider during potential surgery are the brachial plexus branches as well as the brachial artery & vein.
