What can we learn from the errors in the frozen section diagnosis of pulmonary carcinoid tumors? An evidence-based approach

Diagnostic challenges of intra-operative frozen consultation for gastrointestinal signet ring cell carcinoma†

AIMS

Signet ring cell carcinoma (SRCC) is challenging to recognise on intra-operative frozen sections, with known high false-negative rates. The objective of this study was to investigate common factors contributing to discrepancies between intra-operative frozen diagnoses and those made upon review of permanent sections, and summarise our experiences gained and lessons learned on minimising errors on intra-operative frozen diagnoses of gastrointestinal SRCC.

METHODS AND RESULTS

We retrospectively examined our pathology database from 25 May 2000 to 1 January 2018 and re-reviewed intra-operative frozen sections and permanent haematoxylin and eosin (H&E) slides for specimens confirmed with SRCC on permanent sections. This study includes 83 specimens taken from 50 patients, with an accuracy of 85.5%. Main common factors causing discordance or deferral in recognising SRCC between intra-operative frozen procedures and permanent sections include: (i) resemblance of clusters of SRCC cells with a myxoid background; (ii) disguise as normal or reactive cells (histiocytes, macrophages, large reactive lymphocytes, plasma cells or adipocytes) due to their relatively clear or depleted cytoplasmic mucin; and (iii) histological sampling errors, leading to misses of small foci of SRCC on frozen section slides.

CONCLUSIONS

An accurate diagnosis of SRCC during intra-operative frozen consultations remains challenging. Based on our experiences and lessons, the most important strategies to reduce diagnostic errors are: (i) understanding the unusual histomorphological features of SRCC cells on frozen sections including, but not limited to, intracellular mucin depletion, absence of desmoplasia and no adjacent pre-cancer changes; and (ii) close attention to abrupt transition from normal architecture (e.g. glandular or submucosal loose connective tissue) to myxoid and/or inflammatory-like appearance, which potentially harbours SRCC.

Neuroendocrine Tumors of the Lung: Updates and Diagnostic Pitfalls

Neuroendocrine tumors of the lung constitute approximately 20% of all primary lung tumors and include typical carcinoid, atypical carcinoid, small cell carcinoma, and large cell neuroendocrine carcinoma. Given their morphologic overlap with diverse mimics, neuroendocrine tumors of the lung can be diagnostically challenging. This review discusses the clinical, histologic, immunophenotypic, and molecular features of pulmonary neuroendocrine tumors, along with common diagnostic pitfalls and strategies for avoidance.

[Surgical Resection and Prognosis of Bronchopulmonary Carcinoid]

BACKGROUND

Bronchopulmonary carcinoid (BPC) is a rare neuroendocrine tumor, the clinical studies on treatment and prognostic factors of BPC are somewhat controversial. Our purpose was to evaluate the clinical efficacy of surgery on BPC, and to analyze the prognostic factors affecting the survival of BPC.

METHODS

We retrospectively collected the clinical data of patients with BPC admitted to the Chinese PLA General Hospital between January 2000 and December 2017. The Kaplan-Meier method was used to calculate the survival rate of patients and to map the survival curve. Then the effects of different factors like pathological classification, gender, age, on prognosis were compared by univariate analysis and multivariate analysis was made by Cox proportional hazard model.

RESULTS

A total of 98 patients had a diagnosis of BPC were included in the study. There were 41 patients with typical carcinoid (TC) and 57 patients with atypical carcinoid (AC). The 1-yr, 5-yr, and 10-yr overall survival rates of BPC were 96.9%, 80.0% and 73.6%, respectively. Univariate analysis showed age (P=0.000,1), smoking history (P=0.005), pathological subtype (P<0.000,1), T stage (P=0.000,2), TNM stage (P<0.000,1) were the prognostic factors. Multivariate analysis showed that age (P=0.005) and tumor stage (P=0.017) were independent prognostic factors.

CONCLUSIONS

BPC occurred more in middle-aged men. Surgery is the main treatment for lung cancer, and the overall prognosis is good. Age and TNM stage were independent risk factors for long-term survival after lung cancer surgery.

Surgical Resection for Pulmonary Carcinoid: Long-Term Results of Multicentric Study-The Importance of Pathological N Status, More Than We Thought

BACKGROUND

Histological subdivision into typical (TC) and atypical (AC) is crucial for treatment and prognosis of lung carcinoids but can be also very challenging, even for experts. In this study, we aimed to strengthen or reduce the prognostic value of several pathological, clinical, or per-operative factors some of which are still controversial.

METHODS

We retrospectively reviewed clinical records related to 195 patients affected by TC (159) or AC (36) surgically treated between 2000 and 2014, in three different centers. Survival and subtypes comparison analyses were performed to identify potential prognostic factors.

RESULTS

TCs showed a lower rate of nodal involvement than ACs (N0 = 94.9%; N1 = 1.9%; N2 = 3.2% in typical and N0 = 63.8%; N1 = 16.6%; N2 = 19.4% in atypical carcinoids, respectively, p < 0.0001). Long-term oncological results of resected carcinoids were significantly better in TCs than ACs with higher 5- and 10-year overall survival rates (97.2 and 88.2% vs. 77.9 and 68.2%, respectively; p = 0.001) and disease-free survival rates (98.2 and 90.3% in typical and 80.8 and 70.7% atypical carcinoids, respectively; p = 0.001). Risk factors analysis revealed that AC subtype [HR 4.33 (95% CI 1.72-8.03), p = 0.002], pathological nodal involvement [HR 3.05 (95% CI 1.77-5.26), p < 0.0001], and higher SUV_max [HR 4.33 (95% CI 1.03-7.18), p = 0.002] were independently and pejoratively associated with overall survival. Factors associated with a higher risk of recurrence were AC subtype [HR 6.13 (95% CI 1.13-18.86), p = 0.002]; nodal involvement [HR 5.48 (95% CI 2.85-10.51), p < 0.0001]; higher Ki67 expression level [HR 1.09 (95% CI 1.01-1.20), p = 0.047]; and SUV_max [HR 1.83 (95% CI 1.04-3.23), p = 0.035].

CONCLUSION

Surgery for lung carcinoids allows satisfactory oncological results which mainly depend on carcinoid subtype dichotomy, pathological nodal status, and SUV_max.

Evidence-based pathology: systematic literature reviews as the basis for guidelines and best practices

CONTEXT

Evidence-based medicine has been proposed as a new paradigm for the identification and evaluation of medical information. Best available evidence or data are identified and used as the basis for the diagnosis and treatment of individual patients. Evidence-based pathology has adapted basic evidence-based medicine concepts to the specific needs of pathology and laboratory medicine.

OBJECTIVES

To briefly review the history and basic concepts of evidence-based medicine and evidence-based pathology, describe how to perform and interpret systematic reviews, and discuss how to integrate best evidence into guidelines.

DATA SOURCES

PubMed (National Library of Medicine, Washington, DC) and Web of Science (Thompson Reuters, New York, New York) were used.

CONCLUSIONS

Evidence-based pathology provides methodology to evaluate the quality of information published in pathology journals and apply it to the diagnosis of tissue samples and other tests from individual patients. Information is gathered through the use of systematic reviews, using a method that is less biased and more comprehensive than ad hoc literature searches. Published data are classified into evidence levels to provide readers with a quick impression about the quality and probable clinical validity of available information. Best available evidence is combined with personal experience for the formulation of evidence-based, rather than opinion-based, guidelines that address specific practice needs.

Pathology and diagnosis of neuroendocrine tumors: lung neuroendocrine

Neuroendocrine (NE) tumors of the lung include a spectrum from low-grade typical carcinoid (TC) and intermediate-grade atypical carcinoid (AC) to high-grade large cell neuroendocrine carcinoma (LCNEC) and small cell lung carcinoma (SCLC). Although NE lung tumors are frequently discussed together, as in this article, carcinoids are very different from high-grade SCLC and LCNEC. SCLC and LCNEC are found in heavy-smoking, older patients, whereas smoking is not strongly associated with carcinoid tumors. On a molecular level, SCLC and LCNEC have extensive genetic abnormalities, but there are few in TC and slightly more in AC.

Pulmonary neuroendocrine tumors: study of 90 cases focusing on clinicopathological characteristics, immunophenotype, preoperative biopsy, and frozen section diagnoses

BACKGROUND AND OBJECTIVES

Pulmonary neuroendocrine tumors have a prognostic spectrum including typical carcinoid (TC), atypical carcinoid (AC), small cell carcinoma (SCLC), and large cell neuroendocrine carcinoma (LCNEC). We conducted a retrospective study to compare their clinicopathological characteristics, immunophenotype, preoperative biopsy and frozen section diagnoses, and prognosis.

METHODS

Ninety cases of surgically treated pulmonary neuroendocrine tumors were studied. Immunohistochemical studies were performed using antibodies to chromogranin A, synaptophysin, and CD56. The preoperative biopsy and frozen section diagnoses were reviewed.

RESULTS

The 5-year survival rates for TC, AC, SCLC, and LCNEC were 96.6%, 66.7%, 42.4%, and 38.0%, respectively. T stage and pleural status correlated with outcome of SCLC and LCNEC, but N-stage and overall TNM stage did not. In preoperative biopsy, accurate diagnosis was achieved in 5 of 11 TC, 2 of 4 AC, 6 of 15 SCLC, and 0 of 5 LCNEC cases. Using frozen sections, accurate diagnosis was achieved in 8 of 12 TC, 2 of 11 SCLC, and 0 of 11 LCNEC cases.

CONCLUSIONS

LCNEC was the most difficult to diagnose using either preoperative biopsy or frozen sections. T stage and pleural status can predict outcome of SCLC and LCNEC.

Root cause analysis of problems in the frozen section diagnosis of in situ, minimally invasive, and invasive adenocarcinoma of the lung

CONTEXT

Frozen sections can help determine the extent of surgery by distinguishing in situ, minimally invasive, and invasive adenocarcinoma of the lung.

OBJECTIVE

To evaluate our experience with the frozen section diagnosis of these lesions using root-cause analysis.

DESIGN

Frozen sections from 224 consecutive primary pulmonary adenocarcinomas (in situ, 27 [12.1%]; minimally invasive, 46 [20.5%]; invasive, 151 [67.4%]) were reviewed. Features that could have contributed to frozen section errors and deferrals were evaluated.

RESULTS

There were no false-positive diagnoses of malignancy. Frozen section errors and deferrals were identified in 12.1% (27 of 224) and 6.3% (14 of 224) of the cases, respectively. Significantly more errors occurred in the diagnosis of in situ and minimally invasive adenocarcinoma than in the diagnosis of invasive adenocarcinoma (P < .001). Frozen section errors and deferrals were twice as frequent in lesions smaller than 1.0 cm (P = .09). Features significantly associated with errors and deferrals included intraoperative consultation by more than one pathologist (P = .003) and more than one sample of frozen lung section (P = .001). Inflammation with reactive atypia, fibrosis/scar, sampling problems, and suboptimal quality sections were identified in 51.2% (21 of 41), 36.6% (15 of 41), 26.8% (11 of 41), and 9.8% (4 of 41) of the errors and deferrals, respectively (more than one of these factors was identified in some cases). Frozen section errors and deferrals had significant clinical impact in only 4 patients (1.8%); each had to undergo completion video-assisted thoracoscopic lobectomy less than 90 days after the initial surgery.

CONCLUSIONS

The distinction of in situ from minimally invasive adenocarcinoma is difficult in both frozen and permanent sections. We identified several technical and interpretive features that likely contributed to frozen section errors and deferrals and suggest practice modifications that are likely to improve diagnostic accuracy.

Evidence-Based Principles in Pathology: Existing Problem Areas and the Development of “Quality” Practice Patterns

Context.—Contrary to the intuitive impressions of many pathologists, several areas exist in laboratory medicine where evidence-based medicine (EBM) principles are not applied. These include aspects of both anatomic and clinical pathology. Some non-EBM practices are perpetuated by clinical “consumers” of laboratory services because of inadequate education, habit, or overreliance on empirical factors. Other faulty procedures are driven by pathologists themselves.

Objectives.—To consider (1) several selected problem areas representing non-EBM practices in laboratory medicine; such examples include ideas and techniques that concern metastatic malignancies, “targeted” oncologic therapy, general laboratory testing and data utilization, evaluation of selected coagulation defects, administration of blood products, and analysis of hepatic iron-overload syndromes; and (2) EBM principles as methods for remediation of deficiencies in hospital pathology, and implements for the construction of “quality” practices in our specialty.

Data Sources.—Current English literature relating to evidence-based principles in pathology and laboratory medicine, as well as the authors' experience.

Conclusions.—Evidence-based medicine holds the promise of optimizing laboratory services to produce “quality” practices in pathology. It will also be a key to restraining the overall cost of health care.

Evidence-based evaluation of the risks of malignancy predicted by thyroid fine-needle aspiration biopsies

A National Cancer Institute (NCI) "Thyroid Fine-Needle Aspiration (FNA) State of the Science Conference" recently proposed standardized nomenclature and "risks of malignancies" associated with various diagnostic categories. We evaluated the evidence levels of the data used by NCI to predict malignancy risks and whether those estimates had clinical validity in our patient population.Eight hundred seventy-nine patients underwent thyroid FNA during 2006. FNA diagnoses were translated into NCI diagnostic categories, and 2-year follow-up retrospective information was obtained. Four percentages of malignancies were calculated for each diagnostic category using follow-up information from FNA, thyroidectomy, both, and all patients as denominators. 95% confidence intervals (CI) were estimated for all proportions, and results were analyzed with chi-square statistics. "Relative risk" calculations were performed using the percentage of malignancies in the entire population under study as a denominator.Most of the studies cited by the NCI provided incomplete and variable level III evidence based mainly on surgical follow-up. Among our patients, the percentages of malignancies calculated with follow-up data from all patients as the denominator were similar to the "risk estimates" proposed by the NCI, but estimates based on surgical follow-up overestimated the probability of thyroid malignancy for patients with FNA diagnosis of "benign" and "follicular lesions of undetermined significance" (FLUS). Relative risk and 95% CI calculations suggested that the NCI classification could be simplified into three categories: "benign," "FLUS + neoplasm," and "suspicious + malignant."

Pulmonary Neuroendocrine Tumors

Pulmonary neuroendocrine tumors are frequently encountered as small biopsy and resection specimens. Although the World Health Organization (WHO) classification is used as a diagnostic framework globally and in daily practice, it is not without controversy and practical difficulties. The WHO criteria for pulmonary neuroendocrine tumors are reviewed with the recognition that the definitions are based on resected specimens, which are often not the usual clinical circumstances. A practical approach is emphasized, and the differential diagnosis is discussed with particular attention to the context in which diagnostic difficulties are most frequently encountered, such as small biopsies and frozen sections.

Diagnosis of Metastatic Neoplasms: A Clinicopathologic and Morphologic Approach

Context.—The diagnosis of the site of origin of metastatic neoplasms often poses a challenge to practicing pathologists. A variety of immunohistochemical and molecular tests have been proposed for the identification of tumor site of origin, but these methods are no substitute for careful attention to the pathologic features of tumors and their correlation with imaging findings and other clinical data. The current trend in anatomic pathology is to overly rely on immunohistochemical and molecular tests to identify the site of origin of metastatic neoplasms, but this “shotgun approach” is often costly and can result in contradictory and even erroneous conclusions about the site of origin of a metastatic neoplasm.

Objective.—To describe the use of a systematic approach to the evaluation of metastatic neoplasms.

Data Sources.—Literature review and personal experience.

Conclusions.—A systematic approach can frequently help to narrow down differential diagnoses for a patient to a few likely tumor sites of origin that can be confirmed or excluded with the use of selected immunohistochemistry and/or molecular tests. This approach involves the qualitative evaluation of the “pretest and posttest probabilities” of various diagnoses before the immunohistochemical and molecular tests are ordered. Pretest probabilities are qualitatively estimated for each individual by taking into consideration the patient's age, sex, clinical history, imaging findings, and location of the metastases. This estimate is further narrowed by qualitatively evaluating, through careful observation of a variety of gross pathology and histopathologic features, the posttest probabilities of the most likely tumor sites of origin. Multiple examples of the use of this systematic approach for the evaluation of metastatic lesions are discussed.