Diagnostic utility and pitfalls of intraoperative pulmonary imprint cytology based on final pathological diagnoses

Abstract

Objective: This study aimed to determine the reliability of imprint cytology (IC) for intraoperative diagnosis of pulmonary lesions. Methods:We reviewed 113 cases of pulmonary lesion resection for which a scratch imprint was made intraoperatively. We divided the specimens into two groups (benign and malignant) and compared the scratch IC-based diagnoses against the final histopathological diagnoses in each group for concordance. We also analysed those cases in which the scratch IC preparation was classified as inadequate. Results:The sensitivity, specificity, positive and negative predictive values, and accuracy of IC diagnoses among the patient cohort were 87.7% (72/82), 100% (7/7), 100% (72/72), 41.2% (7/17) and 88.8% (79/89), respectively. IC yielded some falsenegative results in terms of malignancy, although most of these imprints were of early cancer or cancer with mild cytological atypia. Five (41.6%) of 12 lesions for which the imprint was deemed inadequate were diagnosed histologically as granulomas with caseous necrosis. Conclusion: IC-based diagnoses of pulmonary lesions as malignant correspondedwell with the final histopathological diagnoses, but IC-based diagnoses of negative (ie, without malignant cells) were not as reliable. Thus, pathologists should recognise the limitations of IC, especially for identifying malignant lesions. Also, the possibility of latent bacterial infection in a granuloma with caseous necrosis indicates that an IC preparation deemed inadequate for diagnosis should not be ignored. K E Y W O R D Sgranuloma with caseous necrosis, imprint cytology, intraoperative diagnosis, pulmonary lesion

A biosafety algorithm for the protection of pathology staff during intraoperative examinations of pulmonary lesions

“…Thirteen (81%) of the 16 lesions for which the imprint was classified as ‘inadequate’ turned out to be benign, either inflammatory lesions or intrapulmonary lymph nodes. Diagnosis of such lesions is not dependent on the epithelial component, and in the case of caseous necrosis, for example, the sample may consist only of solid material without an epithelial component, despite the fact that the target lesion is scratched . As shown in Table , we reconfirmed seven of eight cases (88%) with caseous necrosis including coagulative necrosis classified as inadequate (group D).…”

“…Thus, the pathologist should ask the surgeon during surgery whether tuberculous infection is a possibility when the scratch imprint is ‘inadequate’ or when caseous necrosis or abscess is seen macroscopically, and then decide whether to continue the examination by making a frozen section. Also, a majority of cases determined histologically to be cases of granuloma with caseous necrosis are associated with pulmonary nontuberculous mycobacteria or Cryptococcus and not Mycobacterium tuberculosis , as documented in our previous study . Thus, it is essential to perform PCR testing to determine whether M. tuberculosis is present before a permanent formalin‐fixed section is made.…”

“…To test and compare the diagnostic sensitivity, specificity, positive and negative predictive value (NPV), and accuracy of intraoperative scratch‐IC and frozen sectioning, we compared the final pathological diagnoses with those obtained intraoperatively. When discordance between the scratch‐IC diagnosis and the final pathological diagnosis or between the frozen section diagnosis and the final pathological diagnosis was found, we determined the pitfalls and limitations of these two procedures, as described in our previous study . Category II/group B (indefinite for neoplasia) and group D (inadequate) samples were excluded from the analysis of diagnostic sensitivity, specificity, PPV or NPV, and accuracy; however, we did assess the samples judged to be equivocal or inadequate, whether by scratch‐IC or by frozen sectioning, in terms of the final pathological diagnoses.…”

“…In a previously reported study, we examined whether and in what circumstances scratch‐imprint cytology (IC) can be relied upon in lieu of frozen sectioning for rapid intraoperative diagnoses of pulmonary lesions. In that study, we showed a strong association between a scratch‐IC diagnosis of malignancy and the final pathological diagnosis, although no such relationship was found with a scratch‐IC diagnosis of benign lesion or tumor without malignant cells.…”

“…Regardless of of the cryotome/cryostat use and design, biosafety remains an issue because in cases of tuberculosis infection, for example, bacteria can be released into the room air from a pulmonary specimen that has not been sterilized. [7][8][9] In a previously reported study, 10 we examined whether and in what circumstances scratch-imprint cytology (IC) can be relied upon in lieu of frozen sectioning for rapid intraoperative diagnoses of pulmonary lesions. In that study, we showed a strong association between a scratch-IC diagnosis of malignancy and the final pathological diagnosis, although no such relationship was found with a scratch-IC diagnosis of benign lesion or tumor without malignant cells.…”