Cytological, histopathological, histochemical, and immunohistochemical findings of multiple cutaneous nodules in a bovine

This case study describes the cytological and histopathological findings of cutaneous masses in a bovine, including a peripheral nerve sheath tumor (PNST), vaccine-associated granulomatous inflammation, and eosinophilic inflammation due to parasitosis. A six-year-old undefined cow (SRD) presented with heterogeneous cutaneous lesions including multiple nodules in the left paralumbar fossa, bilaterally at the withers, and scattered along the dorsum, limbs and near the tail; some lesions were associated with ticks. Cytology of these nodules showed benign mesenchymal neoplasia (paralumbar fossa), granulomatous and pyogranulomatous inflammation (withers) and keratin (dorsum). Histopathology, in this order, confirmed PNST. post-vaccination granuloma, and eosinophilic dermatitis. A peripheral nerve sheath tumor was suspected based on the histological findings, showing a well-delineated proliferation of fusiform cells arranged in plexiform structures, which appeared red by Masson's Trichrome stain. The diagnosis was confirmed by immunohistochemistry (anti-S100 antibody). Vaccine reaction often occurs in cattle, and cytological examination is sufficient to determine the inflainmatory process. Eosinophilic dermatitis is usually accompanied by perivascular inflammation and reflects the exfoliative process by the oral apparatus of the parasite.