Intramuscular desmoid tumor (musculoaponeurotic fibromatosis) in two horses.

The research article discusses the discovery and study of intramuscular desmoid tumors, a type of fibrosis, in two horses, shedding light on its similarities with human desmoid tumors, and proposing that these tumors may have a traumatic origin, such as injections or ruptures.

Finding of Intramuscular Desmoid Tumors in Horses

• The research starts with the identification of intramuscular desmoid tumors in two young adult horses. The tumor in the first horse was found in the lateral cervical musculature while the one in the second horse occurred in the pectoral musculature.
• The tumors were dissected for further investigation, revealing a single central (in the first horse) or multiple central (in the second horse) fluid-filled cavities with associated sterile inflammation.

Characteristics and Similarities with Human Desmoid Tumors

• The tumors in both horses exhibited similar histopathologic features which included the proliferation of fibroblasts and cells expressing muscle actin (myofibroblasts), with extensive dissecting fibrosis within the muscle.
• These characteristics closely mirror those of human desmoid tumors, especially those also known as musculoaponeurotic fibromatosis.

Hypothesis and Treatment

• The researchers propose that the presence of the fluid-filled cavities in these tumors supports the hypothesis that equine desmoid tumors could be traumatic in origin, such as possibly originating from injection sites or bursal ruptures.
• In terms of treatment, surgical excision of the tumor proved curative in the first horse, however, the extensive nature of the tumor in the second horse made surgical excision unfeasible.

This research contributes to our understanding and knowledge about equine desmoid tumors, potentially influencing treatment plans for horses afflicted by this condition, and further bringing into focus the similarities between certain equine and human conditions.