Multiple masses in a horse’s tongue resulting from an atypical perineurial cell proliferative disorder.

The research focuses on an unusual case of proliferative disorder involving perineurial cells in a National show horse, leading to multiple soft masses on the tongue.

Research Context

• The subject of the research was a 5-year-old National Show horse mare that had a soft mass growing on its tongue primarily on the left dorsolateral aspect. Over the next two years, the horse developed several interconnected masses that extended to the tip of the tongue.
• The study was initiated to determine the cause and nature of these unusual proliferations.

Microscopic Examination

• Upon microscopic examination, the researchers discovered that the basis of these masses was thin, spindle-shaped mesenchymal cells that formed dense whorls around both myelinated and unmyelinated nerves.
• The researchers noted that these cells reacted to antibodies directed against vimentin, a type I intermediate filament protein, but did not react to S-100, a family of low molecular weight protein found in vertebrates characterized by two calcium binding sites.

Ultrastructural Examination

• At the ultrastructural level, the study found multiple, concentrically arranged, long and slender cell processes with discontinuous external laminae and many pinocytotic vesicles, tiny vesicles that ‘drink’ extracellular fluid, assisting in phenotyping the proliferative element accurately.
• This detailed examination provided specific insights into the nature of the proliferative disorder affecting the perineurial cells in the horse’s tongue.

Implications and Conjecture

• The results of the study indicated an atypical perineurial cell proliferative disorder, but its classification as a neoplastic (cancerous) growth remained unconfirmed.
• The distinction between a benign proliferative disorder and a malignant neoplastic growth has significant implications for prognosis and potential treatment options, but the study was unable to definitively discern between these possibilities.