Equine Health Update Issue 1 Volume 16 - Page 26

Diagnostic Imaging Quiz Question: A 5-year-old horse is presented with a granulating wound on the palmarolateral aspect of the proximal LF metacarpus, with a draining sinus tract. Evaluate the accompanying radiograph. a) b) c) d) Name the radiographic view. Which additional ONE radiographic view should next be taken to add more information? List the radiological changes present. What is the diagnosis? Answer on page 27 biopsy should include both the neoplastic tissue and its interface with normal appearing skin (Fig 4). Local lymph nodes should be assessed clinically (including iliac lymph nodes, which can be palpated per rectum) and if lymph node involvement is suspected, fine needle aspirates and/or biopsies should be performed when possible to assess metastasis. Secondary spread to regional lymph nodes may support a poor prognosis and may influence the decision to initiate treatment. In man, several variations of SCC grading have been described (Chaux et al. 2009; Sobin et al. 2010). Equine MC-SCC have been evaluated and grouped by differentiation grade, following histopathological characteristics used in human medicine (Chaux et al. 2009). This criteria defines G1 (grade 1) lesions as well-differentiated tumours, with neoplastic cells nearly identical to normal or hyperplastic squamous cells. In contrast, G3 (grade 3) lesions are considered poorly differentiated with anaplastic squamous cells that contain high nuclear : cytoplasmic ratio, numerous mitotic figures, clumped chromatin and prominent nucleoli. Grade 2 (G2) tumours describe moderately differentiated squamous cells and do not fit into criteria described for either G1 or G3 lesions. In a recent study, 81 equine MC-SCC were grouped by differentiation grade based on histopathology; metastasis was confirmed in 44% of tumours graded as G3, compared to 25% forG2and only 3% for G1. Eighty percent of the G3 tumours had an unsuccessful outcome (i.e. tumour recurrence or euthanasia; van den Top et al. 2011). Taken together, these data suggest that the G1–G3 grading scale may be beneficial in characterising equine MC-SCC and predicting outcome in affected horses. Treatment Several modalities have been recommended for treatment of equine MC-SCC; these are most successful when treatment is initiated early in the course of disease. Surgical management, cryotherapy, hyperthermia, radiotherapy, chemotherapy and photodynamic therapy are used with degrees of success relative to the accessibility and invasiveness of the tumour. Conventional excision Ann Carstens, BVSc, MS, MMedVet(Large Animal Surgery), MMedVet (Diagnostic Imaging), DTE, PhD 26 Surgical excision is typically performed on tumours in which a satisfactory surgical margin of 0.5–1.0 cm can be achieved; however, higher rates of recurrence have been reported with excision of ocular MC-SCC without concomitant use of adjunctive therapy (King et al. 1991; Mosunic et al. 2004). Therefore, adjunctive treatments are often used following surgical debulking of MC-SCC. Depending on size and location of male genital MC-SCC, surgical • Equine Health Update •