Pancreatic Tumors. Группа авторов

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СКАЧАТЬ atypical demonstrate cytologic and architectural alterations that are greater than reactive atypia, but less than that of suspicious for malignancy. It is not trivial to repeat pancreatic FNAs diagnosed as atypical as there are a number of individuals involved and use of expensive equipment makes the resource utilization and costs of operative biopsy even greater. The appropriate course of action is dependent on a multidisciplinary review, the functional status of the patient, and the wishes of the patient after clinical consultation [30]. An atypical interpretation on cytology may require additional diagnostic tests such as loss of immunohistochemical staining for the Dpc4/SMAD4 suppressor gene and detection of mutant KRAS that may contribute to management decisions when imaging is suspicious for adenocarcinoma. Ancillary tests such as fluorescent in situ hybridization (FISH) and next-generation sequencing have shown promise in improving diagnostic sensitivity for the detection of malignancy [39, 40]. The related malignancy risk of the atypical category for EUS-FNAs of solid pancreatic masses is 25–100% (mean 58%) [41–43].

      Neoplastic: Benign

      The major lesion in this category is serous cystic neoplasm (SCN), which can either be observed or treated by resection. If imaging, cytology, and cyst fluid biochemistry (CEA and amylase) support an interpretation of an SCN, the patient can be conservatively managed with observation. However, if the patient is symptomatic and there is evidence of significant growth, which increases the risk of hemorrhage and rupture, it is resected.

      Neoplastic: Other

      Pancreatic Neuroendocrine Tumor. PanNETs can either be managed conservatively by observation or by surgery, depending upon the clinical scenario. Very small (close to 1 cm), incidentally discovered PanNETs in elderly patients with multiple comorbid conditions may be managed conservatively. PanNETs may grow very slowly for prolonged periods. Although the majority (50–60%) exhibit malignant behavior, surgical intervention may not be the best option, especially for elderly patients with multiple comorbidities. Hence, PSC has placed PanNETs in the “neoplastic: other” rather than in the “malignant” category so that patients can have more conservative management options as well. Genetic testing for germline mutations may be performed in cases where family or personal history is suggestive of MEN1 or VHL disease. Medical management of functioning PanNETs is available with multiple drugs, especially in non-resectable cases. For patients with metastatic disease, if the disease is restricted to the liver, resection (including the possibility of hepatectomy and transplantation) is warranted for both functioning and non-functioning tumors with the aim of curative resection or debulking/palliative treatment depending on the size and location of the tumor [30]. Radiofrequency ablation or embolization may be considered with or without chemotherapy for liver metastases.

      Solid-Pseudopapillary Neoplasm. Surgical resection is the treatment of choice for SPN.

      Mucinous Cystic Neoplasm. MCNs are mostly benign, with 18% of cases undergoing malignant transformation. Hence, due to the expense and anxiety associated with life-long surveillance, these neoplasms are removed surgically regardless of their grade. However, patients with small cysts and without high-risk imaging features can be managed with observation.

      Intraductal Papillary Mucinous Neoplasms. IPMNs are treated with either surgical resection or observation depending upon the location. IPMNs that involve the main pancreatic duct are treated with resection. IPMNs that involve only branch ducts can be treated by either of the two options. The decision to operate depends upon the presence of worrisome imaging features such as a large cyst size (>3 cm) or a non-enhancing mural nodule. IPMNs with cytological presence of high-grade dysplasia and adenocarcinoma are surgically resected. Figure 1 shows the Fukuoka revised guidelines for the management of MCNs and IPMNs.

      Gastrointestinal Stromal Tumor. Surgical resection is the treatment of choice for localized gastrointestinal stromal tumors (GISTs). For advanced or metastatic c-Kit-positive GISTs, tyrosine kinase inhibitor (TKI) imatinib is used. Patients who develop resistance to TKI are treated with chemotherapy.

      Suspicious

      Suspicious findings on cytology are generally correlated with the clinical and imaging findings, and if radiology favors a malignant neoplasm the patient may be worked up and staged. Biochemical and molecular analytical markers may increase the sensitivity and specificity of the interpretation [26]. If the cytological findings are suspicious whereas imaging findings are benign, then a repeat sampling of the lesion should be considered.

      Positive/Malignant

      Adenocarcinoma of the Pancreas. For adenocarcinomas of the pancreas, if resectable, surgery is the initial option (Whipple’s procedure for tumors in the head or uncinate process and distal pancreatectomy and splenectomy for tumors in the body and tail) with adjuvant chemotherapy. In cases of non-resectable disease or metastatic disease patients are treated with chemotherapy.

      Acinar Cell Carcinoma. Treatment of ACC is similar to that of PDAC.

High-Grade Neuroendocrine Carcinoma (Small Cell and Large Cell Type). These tumors are treated with chemotherapy regimens that are similar to small cell carcinomas of the lung [44].

      Pancreatoblastoma. Surgical resection with adjuvant or neoadjuvant chemotherapy is the preferred treatment for pancreatoblastomas.

      Lymphoma. Lymphomas are medically managed depending upon the specific type, including histologic morphology, flow cytometry, and cytogenetic findings.

      Metastases. Diagnosis of metastasis generally indicates a widespread malignancy that is managed according to its specific subtype.

For further details, strategies provided by surgical and gastrointestinal specialty organizations, including the British Society of Gastroenterology, the Pancreatic Society of Great Britain, the Royal College of Pathology, the Japan Pancreas Society, the International Association of Pancreatology [45, 46], and the National Comprehensive Cancer Network (NCCN) [47], can be referred to.

      Utilization of Ancillary Studies in the Cytologic Diagnosis of Pancreatic Lesions

Ancillary techniques that help in refining the cytological diagnosis are invaluable. A good cell block containing ample material is required. Ancillary tests include biochemical and molecular tests and immunohistochemical and special stains. These tests have diagnostic and prognostic implications. The PSC made recommendations on the utilization of ancillary studies [29]. These are further expanded upon in subsequent chapters of this monograph. Indications for ancillary testing in the pancreas include the following scenarios: differentiation of benign from malignant ductal lesions, diagnosis of primary and metastatic neoplasms, work-up of suspected hematopoietic lesions, and preoperative work-up of pancreatic cysts.

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