Surgical Principles

Histologic Diagnosis

A pathologic diagnosis should be secured before the definitive surgical procedure is performed in most patients. Critical indications include cases where lesions of divergent histologies would dictate different first-line treatments, particularly operative versus nonoperative, where lesion histologic assessment would determine the extent of operative procedure and where neoadjuvant therapy is being planned. The goal of the diagnostic biopsy is to obtain sufficient tissue for complete analysis with minimal risk for complications. Although cytologic sampling may be adequate, a histologic diagnosis is usually preferable. A false–negative cytologic result occurs in 10% to 20% of cancer cases, and false–positive cytologic diagnoses is rarely. Biopsies may underestimate the aggressiveness of a lesion (e.g., atypia or carcinoma in situ instead of invasive cancer) because of tumor heterogeneity and associated sampling error.

Approaches to diagnostic tissue sampling include cytologic aspiration/brushing, core-needle/punch biopsy, incisional biopsy, or excisional biopsy. The latter two can be approached endoscopically, thorascopically, or laparoscopically, with laparoscopic exploration providing the added benefit of assessing the intraabdominal organs and peritoneal surface.

Whereas percutaneous fine-needle aspiration (FNA) or core-needle biopsy is suitable if the mass is easily palpable and can be easily accessed and stabilized by the operator, percutaneous radiographically directed FNA or biopsy enables access to image-identified but deeper or nonpalpable lesions. US-guidance is used for more superficial lesions, offers the advantage of real-time imaging and constant monitoring of the needle position, and carries lower cost and no radiation exposure. computed tomography (CT)–guidance is more beneficial for deeper tumors where better spatial resolution is needed. It is not interfered by air or bone, and administration of intravenous contrast can provide an estimate of tumor vascularity. Common clinical examples are provided below.

Percutaneous FNA with or without US guidance is widely used to evaluate solitary thyroid nodules. An aspirate of cellular material or fluid is obtained using a 21-gauge needle and syringe, differentiating between solid and cystic masses. If a cyst does not completely disappear with aspiration, FNA examination of any residual solid component is necessary. The success of FNA depends on the experience of performer and the interpreter. Lesions can be classified using the Bethesda System for Reporting Thyroid Cytopathology. Papillary, medullary, and anaplastic carcinomas have typical cytologic appearances. Cytology cannot differentiate benign from malignant follicular and Hürthle cell neoplasms. A definitive diagnosis for these thyroid neoplasms depends on histologic examination of the entire excised tumor. Routine FNA has dramatically reduced the number of diagnostic surgical operations for benign thyroid masses.

Core biopsies of solid breast masses are commonly performed to obtain sufficient tissue for histologic analysis. This can be performed with stereotactic imaging or ultrasonography for nonpalpable breast lesions. Using local anesthesia, a small (3-mm) incision is made in the skin through which a coring biopsy needle is directed into the center of the lesion. Typically, a 1- × 10- to 20-mm tissue sample is obtained.

Intraabdominal, thoracic, and retroperitoneal tumors are best accessed under radiographic guidance. Core-needle biopsies offer the advantages of a histologic diagnosis and greater accuracy than the FNA, but carries some risk of hemorrhage. Ultrasonography or CT-guidance is appropriate for hepatic, renal, pancreatic, intraabdominal, and retroperitoneal lesions. Adrenal FNA should be avoided if a pheochromocytoma has not been biochemically excluded. If nonresectable cancer is discovered at abdominal exploration, a confirmatory biopsy should be obtained.

Incisional biopsy removes a larger sample of a tumor mass than needle biopsy. A full-thickness biopsy of a larger skin tumor at the thickest portion of the lesion can provide accurate cutaneous tumor staging. An incisional biopsy of a sarcoma is sometimes performed for diagnosis before proceeding with definitive treatment (e.g., amputation, preoperative chemotherapy, or radiation). An incisional biopsy of an extremity tumor is preferably obtained through a longitudinal rather than a transverse incision because the longitudinal incision can be more readily incorporated with a future curative procedure and is less disruptive to superficial lymphatics. Intraoperative incisional biopsies during thoracotomy and laparotomy are rarely indicated, because tumor spillage is more likely than with FNA or core-needle biopsies.

A diagnostic excisional biopsy is now rarely performed. However, key principles can be illustrated by excisional biopsy of a breast mass, typically used for small localized lesions amenable to complete excision. Skin incision should be circumareolar or situated within the elliptical incision that would be used for a mastectomy ( Fig. 9.1 ). If suspecting malignancy, it should be excised with a 1-cm margin of normal tissue ( Fig. 9.2A ). The specimen should be oriented, typically with two sutures and multiple-colored stains ( Fig. 9.2B ), to permit the pathologist to specify which of the margins, if any, is histologically malignant. If frozen-section evaluation of the margins is available, reexcisions can be performed immediately when necessary. When frozen-section evaluation is unavailable, separate, individually labeled margins may be sent and selective reexcision can be performed at a later date, as long as the main specimen had been appropriately oriented. Surgical clips left at the base of the biopsy cavity facilitate accurate partial breast or boost-field radiation therapy after breast-conservation surgery. Small titanium clips provide accurate localization for the radiation oncologist with minimal interference on future images, including magnetic resonance imaging (MRI). Preoperative consultation with a radiation oncologist who would contemplate proton beam therapy should be requested because some radiopaque clips interfere with radiation dosimetry from proton beams.

Staging

Accurate preoperative staging results in the best treatment planning and prognostication. Clinical staging is determined using combined data from physical examination, a variety of radiologic tests (including plain radiographs, ultrasonography, CT, and MRI), and endoscopic examination. High-quality, contrast-enhanced radiologic imaging studies such as ultrasound/endoscopic ultrasonography (US/EUS), CT, and MRI are instrumental in determining the extent of local and distant disease, and in planning the operative procedure. Positron emission tomography (PET)-CT can be especially helpful in the diagnosis of unsuspected metastatic disease (e.g., esophageal cancer; melanoma) and in evaluating patients with possible recurrent cancer (e.g., locally recurrent rectal cancer). ⁶⁸ Ga-DOTATATE PET-CT scans can accurately diagnose and stage many neuroendocrine tumors. In symptomatic patients, skeletal metastases can also be diagnosed with a radioisotope bone scan or correlative plain radiographs. Clinical and pathologic stages of disease for most cancers have been standardized in the American Joint Committee for Cancer (AJCC) TNM system.

Staging mediastinoscopy, thoracoscopy, and laparoscopy are additional tools for clinical staging. They allow for visualization of intrathoracic or peritoneal surfaces; histologic evaluation of peritoneal, omental, or hepatic masses; sampling of lymph nodes; and collection of ascites or peritoneal washings for cytologic examination. These are commonly used for pulmonary, gastric, pancreatic, and hepatobiliary cancers, because detection of metastatic disease will spare the patients of the morbidity from tumor resection. Concurrent laparoscopic ultrasonography can further stage pancreatic and hepatobiliary malignancies, whereas in other cases concurrent laparoscopic palliative interventions can be performed.

An illustrative clinical example is the use of staging laparoscopy for pancreatic and periampullary carcinomas. Hepatic or peritoneal metastases undetectable by radiographic means occur in up to 30% of patients with tumors believed to be resectable preoperatively. A complete laparoscopic inspection of the abdominal cavity can be undertaken ( Fig. 9.3 ). Inspection of the upper abdomen, looking for small hepatic metastases or drop metastases on the parietal and visceral peritoneum or the greater omentum, can be readily accomplished. Any suspicious lesions should be sampled; dependent areas should be inspected for tumor seeding and for ascites. Evidence of direct local invasion into adjacent organs should be assessed. From the reverse Trendelenburg position, limited visualization of the anterior pancreas may be obtained with a supragastric approach after division of the lesser omentum ( Fig. 9.4A ) or an infragastric approach, entering the lesser sac through the gastrocolic omentum ( Fig. 9.4B ). Laparoscopic ultrasonography can assess visceral vascular involvement and deep hepatic metastases, although EUS provides highly accurate staging in these sites.