Veterinary Surgical Oncology. Группа авторов

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Biopsy

      Excisional Biopsy

      Excisional biopsy involves removal of the skin tumor with a margin of normal tissue in all planes. The potential advantage of an excisional biopsy is that it provides both a diagnosis and definitive treatment in one surgical episode. Excisional biopsy is best suited for small masses with benign or low‐grade features of malignancy on FNA cytology in anatomical locations that allow for wide resection. Inappropriate use of excision biopsy can result in incomplete surgical margins compromising the optimal treatment options for a patient. Bacon et al. (2007) reported on 41 cases of unplanned excisional resection of soft tissue sarcoma skin masses that resulted in incomplete resection. Only 41% of cases in that study had preoperative FNA cytology performed, and 59% percent of cases did not have a presurgical biopsy procedure, highlighting the need for appropriate preoperative diagnostic evaluation.

      Regional Lymph Node Assessment

      All regional lymph nodes should be assessed by palpation to assess size, firmness, and adherence to underlying structures and FNA cytology regardless of size as part of the evaluation of a cutaneous mass. The sensitivity and specificity of FNA cytology for diagnosis of metastatic disease in lymph nodes in solid neoplasms is 91–100% and 91–96%, respectively, compared to histopathology of the entire lymph node (Langenbach et al. 2001; Ku et al. 2017). Factors reported contributing to discrepancies between cytology and histology include focal distribution of metastases and poorly defined criteria for metastatic mast cell tumors (Ku et al. 2017). False‐positives results with cytology were more common with mast cell tumors and melanomas (Ku et al. 2017). Carcinomas are reported to metastasize to regional lymph nodes more frequently than sarcomas (Langenbach et al. 2001). Lymph node size is not predictive for metastatic status. Incisional or excisional biopsy and histologic assessment of the regional lymph node is the optimal approach to lymph node assessment.

      Identification and biopsy of the first draining regional lymph node, the sentinel lymph node (SLN), is important in the prediction of survival for a variety of cancers in human and veterinary oncology (Tuohy et al. 2009; Beer et al. 2018). The anatomically closest regional LN is not necessarily the SLN, so SLN mapping is recommended. The sentinel lymph node can be identified using a variety of techniques including lymphoscintigraphy (Worley 2014), CT lymphography (Brissot and Edery 2017; Grimes et al. 2017; Majeski et al. 2017; Rossi et al. 2018), and methylene blue. SLN mapping and sampling allows identification of microscopic metastatic disease that would otherwise have been undetected. In such circumstances, clinical stage changes and consequently additional therapy is recommended that would have otherwise not been offered. This can lead to an improved oncologic outcome (Worley 2014).

      Preoperative Diagnostic Imaging

      Diagnostic imaging is used to evaluate for evidence of metastatic disease as part of the staging process. Three‐view thoracic radiographs or CT are used most commonly to evaluate for pulmonary metastases and thoracic lymph node involvement, and abdominal ultrasonography or CT for evaluation of abdominal lymph nodes and intraabdominal metastases.

Photo depicts (a, b) nNoncontrast and contrast CT scan imaging of an interscapular vaccine-associated sarcoma in a cat used to plan deep surgical resection margins.

      Radiation therapy can be used as an effective primary local therapy or as an adjunctive treatment in combination with surgery. Squamous cell carcinoma, basal cell carcinoma, cutaneous lymphoma, and mast cell tumors (MCTs) are the most radiation‐sensitive skin tumors.

      Chemotherapy is the preferred treatment option for some of the round cell tumors, such as lymphoma, transmissible venereal tumor, and some mast cell tumors.

      Principles of Surgical Excision

      Surgical instruments, drapes, and gloves should be changed immediately, and intraoperative lavage should be done, if the tumor is entered inadvertently or if an intracapsular resection is done and the change should be performed routinely after malignant tumor excision.

      Postoperative surgical drains should be avoided as they can potentially contaminate the normal tissues through which they pass with tumor cells; however, they should be considered if surgery results in a large dead space or is in a high‐motion anatomical


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