Root cause analysis of indeterminate diagnoses in serous fluids cytopathology

Abstract

Introduction The International System for Reporting Serous Fluid Cytopathology proposed five diagnostic categories: Nondiagnostic (ND), Negative for Malignancy (NFM), Atypia of Undetermined Significance (AUS), Suspicious for Malignancy (SFM) and Malignant (MAL) (Primary or Metastatic). The indeterminate (AUS/SFM) categories are challenging for management. The goal of this study is to reveal the root causes contributing to indeterminate diagnoses (ID). Materials and Methods We searched our archives between 1 January 2017 and 30 June 2019, and performed a root cause analysis (RCA) using the “5 whys” method to determine the contributing factors of ID. Results Nine hundred eleven specimens were evaluated and diagnosed: ND (9, 1%), NFM (667, 73.2%), AUS (51, 5.6%), SFM (27, 3%) and MAL (157, 17.2%). More than one factor contributed to 38/78 ID. Low volume (<50 cc), and low cellularity were identified in 31 and 51 cases, respectively. Three cases were simply deferred to concurrent biopsy. Eleven cases were called atypical, favor reactive mesothelium despite confirmatory IHC. Atypical lymphoid population was reported in seven cases. Cellblocks (CB) were low in cellularity despite volume >1000 mL in 13 cases. Two mesotheliomas were underdiagnosed as suspicious. Conclusions Low cellularity and low volume were the most common contributing factors, highlighting the importance of adequate sample collection. Adequate volume specimens with low cellularity may benefit from a close inspection and a second CB. Some IDs can be switched to NFM or MAL with careful consideration of clinical, radiologic findings and ancillary testing, and concurrent surgical pathology correlation when available.

A retrospective analysis of pleural effusion specimens based on the newly proposed International System for Reporting Serous Fluid Cytopathology

“…A total of 2454 patients were included, among which 30 (1.2%), 1670 (68.1%), 549 (22.4%), 151 (6.2%) and 54 (2.2%) in patients were classified into ND, NFM, AUS, SFM and MAL groups, respectively. Overall, most of the pleural effusion specimens (90.4%, n = 2219/2454) were diagnosed as “benign” or “malignant,” and the remaining (8.4%) were diagnosed as “AUS” or “SFM.” These results were similar to those reported in previous studies 7,9,12,13 …”

“…The benign and malignant specimens with qualitative or quantitative cytologic components were diagnosed as “AUS.” 1,5,9 Among the 151 AUS cytology samples, male patients were slightly more than female patients (n = 84 vs. 67, 55.6% vs. 44.4%), with a mean age of 71 years (Table 1). Most of the patients in AUS group had a prior malignancy history ( n = 85, 56.2%), including 2 (2.4%) with sarcoma, 8 (9.4%) with hematologic malignancy and 75 (88.2%) with carcinoma (Table 3).…”

“…ROM was estimated according to the previously described methods 8,9,12 . Performance evaluation was conducted by measuring diagnostic accuracy, sensitivity, specificity, positive and negative predictive values for each pleural effusion sample 7,13 .…”

“…At present, only a limited number of studies have supported the use of a particular terminology for serous fluid cytology 6‐11 . In this study, we applied TIS recommendations for reporting the cytological diagnosis of pleural effusion.…”

Serous fluid cytopathology: Past, present, and future

“…Recognizing the need to minimize indeterminate diagnosis, Gokozan et al performed a root cause analysis of the diagnoses of atypia or suspicious for malignancy. Among the root causes that emerged, several were related to specimen volume and cell block processing 20 …”