Atypical Cutaneous Fibroma in a Cow

Abstract

Background: Cutaneous fibroma is a benign neoplasm affecting the fibroblasts and collagen matrix that develops in the dermis or subcutaneous tissue. This neoplasm is uncommon in cattle, and few reports have described the treatment and resolution of this neoplasm. Despite its benign character, a veterinarian should consider cutaneous fibroma in the differential diagnosis of skin tumorshis report aims to describe a rare case of large fibroma in the scapular region in a cow, with emphasis on the clinical-surgical and anatomopathological aspects of the condition.

Case: A 3-year-old Girolando 3/4 cow was attended to at a rural property in Lagamar-MG, Brazil. According to the owner, the animal presented with a small mass in the right scapular region that grew progressively over 1 year and 6 months. Clinical examination revealed an exuberant and painless increase in volume on palpation in the proximal region of the right thoracic limb, which, in its vertical axis, extended from the proximal end of the scapula to near the olecranon tuberosity, and, in its horizontal axis, extended from the 6^th intercostal space to the scapulohumeral joint, reaching the dimensions 66 cm and 62 cm, respectively. It presented with multiple nodules that were firm in consistency with extensive areas of ulceration. Neoplasia was suspected, and surgical excision was decided upon. The cow was sedated and restrained in the left lateral decubitus position. Trichotomy and antisepsis of the operative field were performed followed by an infiltrative anesthetic block around the tumor. The tumor was excised maintaining a safety margin of 1 cm. Dermorrhaphy was not possible, and healing by secondary intention was awaited. In the postoperative period, antibiotic therapy with benzathine penicillin, analgesia with meloxicam and dipyrone and daily dressing of the wound were performed. There were no postoperative complications and complete healing occurred approximately 100 days after surgery. One year after the surgical procedure, the owner reported that the cow did not present with recurrence of the neoplasm. The resected tumor weighed 11.2 kg, and, when cut, presented with solid conformation and whitish coloration. Tumor fragments were harvested, fixed in 10% formalin, and sent for histopathological examination, which revealed neoproliferation of remarkable cellular density composed of dense, well vascularized fibrocollagenous connective tissue arranged in multidirectional bundles and undulating pattern. Mild cellular pleomorphism was identified, and no mitosis figures were observed. Alcian blue staining was negative for mucopolysaccharides, differing from Masson's trichrome staining, which widely stained the fibrocollagenous tissue blue. In view of these findings, the diagnosis of cutaneous fibroma was confirmed.

Discussion: Cutaneous fibromas are benign neoplasms of fibrous tissue, and they are uncommon in cattle and may be associated with bovine papillomavirus and/or trauma. Although the origin of cutaneous fibroma is not clear, the present report stands out due to the large size of the tumor mass. The complete healing of the surgical wound, the absence of recurrence one year after surgery and the return of the animal to dairy production demonstrate that the surgical treatment was adequate. The macro- and microscopic characteristics of the cutaneous fibroma in this case corroborate with other cases reported in the literature. Large cutaneous fibroma is uncommon in bovines, and may hinder surgical excision and prolong healing time, as well as the complete recovery of the animal. Moreover, the differential diagnosis with other neoplasms of fibroblastic origin is relevant, especially for those with malignant biological behavior, such as fibrosarcoma and myxosarcoma.

Keywords: bovine, cutaneous tumor, fibroblasts, fibroblastic neoplasm, surgery.

Título: Fibromacutâneo atípico em uma vaca

Descritores: bovino, cirurgia, fibroblastos, neoplasia fibroblástica, tumor cutâneo.