CSF cytology-the ongoing dilemma to distinguish neoplastic and inflammatory lymphocytes

Leptomeningeal Disease (LMD) in Patients with Melanoma Metastases

Leptomeningeal disease (LMD) is a devastating complication caused by seeding malignant cells to the cerebrospinal fluid (CSF) and the leptomeningeal membrane. LMD is diagnosed in 5-15% of patients with systemic malignancy. Management of LMD is challenging due to the biological and metabolic tumor microenvironment of LMD being largely unknown. Patients with LMD can present with a wide variety of signs and/or symptoms that could be multifocal and include headache, nausea, vomiting, diplopia, and weakness, among others. The median survival time for patients with LMD is measured in weeks and up to 3-6 months with aggressive management, and death usually occurs due to progressive neurologic dysfunction. In melanoma, LMD is associated with a suppressive immune microenvironment characterized by a high number of apoptotic and exhausted CD4⁺ T-cells, myeloid-derived suppressor cells, and a low number of CD8⁺ T-cells. Proteomics analysis revealed enrichment of complement cascade, which may disrupt the blood-CSF barrier. Clinical management of melanoma LMD consists primarily of radiation therapy, BRAF/MEK inhibitors as targeted therapy, and immunotherapy with anti-PD-1, anti-CTLA-4, and anti-LAG-3 immune checkpoint inhibitors. This review summarizes the biology and anatomic features of melanoma LMD, as well as the current therapeutic approaches.

Analysing cerebrospinal fluid with explainable deep learning: From diagnostics to insights

AIM

Analysis of cerebrospinal fluid (CSF) is essential for diagnostic workup of patients with neurological diseases and includes differential cell typing. The current gold standard is based on microscopic examination by specialised technicians and neuropathologists, which is time-consuming, labour-intensive and subjective.

METHODS

We, therefore, developed an image analysis approach based on expert annotations of 123,181 digitised CSF objects from 78 patients corresponding to 15 clinically relevant categories and trained a multiclass convolutional neural network (CNN).

RESULTS

The CNN classified the 15 categories with high accuracy (mean AUC 97.3%). By using explainable artificial intelligence (XAI), we demonstrate that the CNN identified meaningful cellular substructures in CSF cells recapitulating human pattern recognition. Based on the evaluation of 511 cells selected from 12 different CSF samples, we validated the CNN by comparing it with seven board-certified neuropathologists blinded for clinical information. Inter-rater agreement between the CNN and the ground truth was non-inferior (Krippendorff's alpha 0.79) compared with the agreement of seven human raters and the ground truth (mean Krippendorff's alpha 0.72, range 0.56-0.81). The CNN assigned the correct diagnostic label (inflammatory, haemorrhagic or neoplastic) in 10 out of 11 clinical samples, compared with 7-11 out of 11 by human raters.

CONCLUSIONS

Our approach provides the basis to overcome current limitations in automated cell classification for routine diagnostics and demonstrates how a visual explanation framework can connect machine decision-making with cell properties and thus provide a novel versatile and quantitative method for investigating CSF manifestations of various neurological diseases.

Flow Cytometric Detection of Malignant Blasts in Cerebrospinal Fluid: A Biomarker of Central Nervous System Involvement in Childhood Acute Lymphoblastic Leukemia

Despite the excellent prognosis for children and adolescents with acute lymphoblastic lymphoma (ALL), the involvement of the central nervous system (CNS) represents a major therapeutic challenge. Patients who develop CNS relapse have a very poor prognosis, and since current methods cannot reliably identify patients with CNS involvement or patients at high risk of CNS relapse, all children with ALL receive CNS-directed treatment. The current golden standard for detecting CNS involvement is the assessment of cytomorphology on cytospin slides of cerebrospinal fluid (CSF). This technique is inadequate due to low sensitivity and reproducibility. Flow cytometric analysis of CSF represent a novel, highly specific and sensitive technique for the detection of leukemic cells in the CNS. In prospective studies, CSF flow cytometry demonstrated two to three times higher rates of CNS involvement at diagnosis of childhood ALL than conventional cytospin, and especially demonstrated superior sensitivity in detecting low-level CNS disease. CNS involvement determined via flow cytometry has been linked to a higher risk of CNS relapse and poor outcomes in several studies. In this review, we discuss the central analytical concepts of CSF flow cytometry and summarize the current evidence supporting the use of flow cytometric detection of malignant blasts as a biomarker of CNS involvement in childhood ALL.

Biomarkers of non-infectious inflammatory CNS diseases in dogs - Where are we now? Part I: Meningoencephalitis of unknown origin

Meningoencephalitides of Unknown Origin (MUO) comprises a group of non-infectious inflammatory brain conditions, which frequently cause severe neurological disease and death in dogs. Although multiple diagnostic markers have been investigated, a conclusive diagnosis, at present, essentially relies on postmortem histopathology. However, different groups of biomarkers, e.g. acute phase proteins, antibodies, cytokines, and neuro-imaging markers may prove useful in the diagnostic investigation of dogs with MUO. It appears from the current literature that acute phase proteins such as C-reactive protein are often normal in MUO, but may be useful to rule out steroid responsive meningitis-arteritis as well as other systemic inflammatory conditions. In antibody research, anti-glial fibrillary acidic protein (GFAP) may play a role, but further research is needed to establish this as a consistent marker of particularly Pug dog encephalitis. The proposed diagnostic markers often lack specificity to distinguish between the subtypes of MUO, but an increased expression of interferon-γ (IFN-γ) in necrotizing meningoencephalitis (NME) and interleukin-17 (IL-17) in granulomatous meningoencephalitis (GME) in tissue biopsies may indicate their potential as specific markers of NME and GME, respectively, suggesting further investigations of these in serum and CSF. While neuro-imaging is already an important part of the diagnostic work-up in MUO, further promising results have been shown with Positron Emission Tomography (PET) as well as proton resonance spectroscopy (¹H MRS), which may be able to detect areas of necrosis and granulomas, respectively, with relatively high specificity. This review presents different groups of established and potential diagnostic markers of MUO assessing current results and future potential.

S1 guidelines "lumbar puncture and cerebrospinal fluid analysis" (abridged and translated version)

Introduction

Cerebrospinal fluid (CSF) analysis is important for detecting inflammation of the nervous system and the meninges, bleeding in the area of the subarachnoid space that may not be visualized by imaging, and the spread of malignant diseases to the CSF space. In the diagnosis and differential diagnosis of neurodegenerative diseases, the importance of CSF analysis is increasing. Measuring the opening pressure of CSF in idiopathic intracranial hypertension and at spinal tap in normal pressure hydrocephalus constitute diagnostic examination procedures with therapeutic benefits.Recommendations (most important 3-5 recommendations on a glimpse): The indications and contraindications must be checked before lumbar puncture (LP) is performed, and sampling CSF requires the consent of the patient.Puncture with an atraumatic needle is associated with a lower incidence of postpuncture discomfort. The frequency of postpuncture syndrome correlates inversely with age and body mass index, and it is more common in women and patients with a history of headache. The sharp needle is preferably used in older or obese patients, also in punctures expected to be difficult.In order to avoid repeating LP, a sufficient quantity of CSF (at least 10 ml) should be collected. The CSF sample and the serum sample taken at the same time should be sent to a specialized laboratory immediately so that the emergency and basic CSF analysis program can be carried out within 2 h.The indication for LP in anticoagulant therapy should always be decided on an individual basis. The risk of interrupting anticoagulant therapy must be weighed against the increased bleeding risk of LP with anticoagulant therapy.As a quality assurance measure in CSF analysis, it is recommended that all cytological, clinical-chemical, and microbiological findings are combined in an integrated summary report and evaluated by an expert in CSF analysis.

Conclusions

In view of the importance and developments in CSF analysis, the S1 guideline "Lumbar puncture and cerebrospinal fluid analysis" was recently prepared by the German Society for CSF analysis and clinical neurochemistry (DGLN) and published in German in accordance with the guidelines of the AWMF (https://www.awmf.org). /uploads/tx_szleitlinien/030-141l_S1_Lumbalpunktion_und_Liquordiagnostik_2019-08.pdf). The present article is an abridged translation of the above cited guideline. The guideline has been jointly edited by the DGLN and DGN.

Leptomeningeal Metastasis: The Role of Cerebrospinal Fluid Diagnostics

Background: Metastatic spread into the cerebrospinal fluid (CSF) represents a severe complication of malignant disease with poor prognosis. Although early diagnosis is crucial, broad spectrums of clinical manifestations, and pitfalls of magnetic resonance imaging (MRI) and CSF diagnostics can be challenging. Data are limited how CSF parameters and MRI findings relate to each other in patients with leptomeningeal metastasis.

Methods: Patients with malignant cells in CSF cytology examination diagnosed between 1998 and 2016 at the Department of Neurology in the Hannover Medical School were included in this study. Clinical records, MRI findings and CSF parameters were retrospectively analyzed.

Results: One hundred thirteen patients with leptomeningeal metastasis were identified. Seventy-six patients (67%) suffered from a solid malignancy while a hematological malignancy was found in 37 patients (33%). Cerebral signs and symptoms were most frequently found (78% in solid vs. 49% in hematological malignancies) followed by cranial nerve impairment (26% in solid vs. 46% in hematological malignancies) and spinal symptoms (26% in solid vs. 27% in hematological malignancies). In patients with malignant cells in CSF MRI detected signs of leptomeningeal metastasis in 62% of patients with solid and in only 33% of patients with hematological malignancies. Investigations of standard CSF parameters revealed a normal CSF cell count in 21% of patients with solid malignancies and in 8% of patients with hematological malignancies. Blood-CSF-barrier dysfunction was found in most patients (80% in solid vs. 92% in hematological malignancies). Elevated CSF lactate levels occurred in 68% of patients in solid and in 48% of patients with hematological malignancies. A high number of patients (30% in solid vs. 26% in hematological malignancies) exhibited oligoclonal bands in CSF. Significant correlations between the presence of leptomeningeal enhancement demonstrated by MRI and CSF parameters (cell count, lactate levels, and CSF/Serum albumin quotient) were not found in both malignancy groups.

Conclusion: CSF examination is helpful to detect leptomeningeal metastasis since the diagnosis can be challenging especially when MRI is negative. CSF cytological investigation is mandatory whenever leptomeningeal metastasis is suspected, even when CSF cell count is normal.

Assisting the neurologist in diagnosis of CNS malignancies - Current Possibilities and Limits of Cerebrospinal Fluid Cytology and Immunocytochemistry

OBJECTIVES

In tumorous impairment of CNS, cytological identification of the neoplastic cells in CSF frequently requires the use of ancillary techniques. Our methods are focused on identifying algorithms that increase the probability of identifying CSF malignant cells.

MATERIALS AND METHODS

A total of 1.272 CSF samples from patients with tumorous infiltration of CNS of nonhematologic origin along with 721 samples from patients with hematologic malignancies were analyzed in a complex setting including cytological and immunocytochemical investigations.

RESULTS AND DISCUSSION

In CSF diagnostics we are aware of the limited amount of sample combined frequently with neoplastic oligocytosis. Provided atypical, potentially malignant cells in CSF are found, further investigation(s) should maximize the probability of their identification-an appropriate cytological staining and immunocytochemical panel is to be applied. (i) In cases of known recent malignancy: immunoprofile of the recent neoplasm has been considered in immunocytochemical panel. (ii) In patients with a history of malignancy: The propensity to develop a new different malignancy must be taken into account. (iii) Atypical cells found in the CSF of a patient with a negative history of malignancy: Considering the most frequent clinically silent malignancies, stepwise immunocytochemistry is employed. Three milliliter of initial CSF sample represents the absolute minimum to start with.

CONCLUSIONS

The steps of the laboratory activity targeted on malignancy in the CSF detection can be expected as follows: (i) The sample will be divided for both nonmorphology and cytopathology investigations. (ii) Basic stainings will triage the samples into those with no suspicion of malignancy and the remaining ones. (iii) Special stainings and stepwise immunocytochemistry will be performed in parallel with the nonmorphology investigations.

Accuracy of flow cytometry and cytomorphology for the diagnosis of meningeal involvement in lymphoid neoplasms: A systematic review

Central nervous system (CNS) involvement by lymphoid neoplasms is a relatively infrequent event that demands accurate identification. The purpose of this article is to review studies comparing diagnostic accuracy of flow cytometry (FCM) and cytomorphology (CM) for meningeal involvement from lymphoid neoplasms. Primary publications from the last 26 years were identified searching MedLine, Scopus, and Web of Science and systematically scanning bibliographies of identified articles. Only studies reporting complete results were included. We assessed study quality using the QUADAS-2 tool. For each study, we extracted informations regarding study population, technical details about sample preparation, data analysis, and results. Twenty-seven studies were included. A great heterogeneity regarding study populations and analytical procedures was observed among studies. Percentages of samples giving a positive result with both FCM and CM range from 0.3% to 42.9% among studies, whereas double negative samples go from 0% to 96.3%. Samples with positive FCM but negative CM are reported by 89% (24/27) of the studies with rates ranging from 3.5% to 61.5% of total specimens. On the contrary, samples with positive CM and negative FCM are found in 48% (13/27) of the studies with percentages ranging from 0.5% to 10%. Despite all the differences observed among studies, almost all of them state that employing flow cytometry along with conventional cytology increases the number of positive CSF samples for lymphoma involvement, although a few cases remain in whom only morphology can correctly identify malignant cells. Diagn. Cytopathol. 2016;44:841-856. © 2016 Wiley Periodicals, Inc.

Role of Epstein-Barr virus status and immunophenotypic studies in the evaluation of exfoliative cytology specimens from patients with post-transplant lymphoproliferative disorders

BACKGROUND

Post-transplant lymphoproliferative disorders (PTLDs) are well characterized in tissue sections, but their evaluation in exfoliative cytology specimens is limited. This study reports a 25-year experience with PTLDs in exfoliative cytology specimens.

METHODS

All solid organ or allogeneic stem cell transplant recipients with PTLDs and exfoliative cytology specimens from 1987 to 2011 were identified. The cytomorphology, Epstein-Barr virus (EBV) status, flow cytometry, immunohistochemistry, and molecular studies were reviewed from all exfoliative cytology specimens previously diagnosed as atypical lymphoid proliferations or PTLDs.

RESULTS

A total of 55 patients (age range, 1-72 years) with PTLDs had 434 exfoliative cytology specimens. Thirty-six of the 55 patients (65%) had 54 specimens with abnormal lymphoid proliferations (12% of the specimens), and 26 of these patients had 37 specimens available for review (15 cerebrospinal fluid specimens, 12 peritoneal fluid specimens, 9 pleural fluid specimens, and 1 bronchoalveolar lavage fluid specimen). Thirty percent of the reviewed cytology specimens were diagnostic of PTLDs, including 8 cases of monomorphic post-transplant lymphoproliferative disorder (M-PTLD) with abnormal B/T-cell populations identified with flow cytometry/immunohistochemistry and 3 EBV-positive specimens with a differential diagnosis of polymorphic PTLD versus M-PTLD. All cases diagnostic of a PTLD had 1 to 3 ancillary studies performed. Forty percent of the cytology specimens (15 of 37) were suspicious for a PTLD, but ancillary studies were performed for only a third of them, and they did not support a definitive diagnosis of a PTLD. Thirty percent of the cytology specimens (11 of 37) appeared reactive, but they lacked sufficient ancillary studies to exclude a PTLD.

CONCLUSIONS

Atypical lymphoid proliferations are common in exfoliative cytology specimens from patients with PTLDs, and they require ancillary studies at least including immunophenotyping and EBV evaluations for a definitive diagnosis. Cancer Cytopathol 2016;124:425-35. © 2016 American Cancer Society.

Cytopathology of Vitreous Humor Samples in Routine Practice

OBJECTIVE

To describe findings in vitreous fluid samples in routine cytology practice.

STUDY DESIGN

The pathology archives from 1988 to 2008 at our institution were searched for vitreous samples. The slides were reviewed and clinical and follow-up information was obtained.

RESULTS

One hundred and eighty-two vitreous fluid samples from 166 patients were analyzed. Most of the samples had been collected for vitreous hemorrhage (75 cases). The second reason for vitreous sample cytological evaluation was an intraocular inflammatory process (55 cases). A specific cause of inflammation was found by combining clinical, microbiological and cytopathological findings in 19 cases, i.e. infection in 7, sarcoidosis in 3, retinal necrosis in 3, lens-induced endophthalmitis in 2, uveitis associated with systemic disease in 2, retrobulbar neuritis in 1 and sympathetic ophthalmia in 1. Among the 19 samples from 16 patients collected to rule out malignancy, 8 had a confirmed intraocular malignancy. Malignant cells were observed in 5 cases (3 lymphomas, 1 melanoma and 1 carcinoma). Undiagnosed malignancies included 2 lymphomas and 1 choroidal melanoma. Other samples were collected during surgery for retinal detachment and cataracts.

CONCLUSIONS

In routine practice, cytology of the vitreous fluid is performed in many and varied situations that are most often nonneoplastic. In nonneoplastic cases, cytology is a useful adjunct to vitrectomy, in spite of its limitations.

Modern cerebrospinal fluid analyses for the diagnosis of diffuse large B-cell lymphoma of the CNS

CNS lymphomas represent rare and aggressive variants of extranodal non-Hodgkin's lymphomas, which may present with diverse neurological symptoms and are often diagnostically challenging. Primary CNS lymphomas develop within the CNS and characteristically involve the brain, leptomeninges, eyes and, in rare cases, spinal cord. Secondary CNS lymphomas are characterized by expansion of systemic lymphomas to the CNS. Multimodal investigation of cerebrospinal fluid (CSF) comprises an important component of the diagnostic work-up for patients with suspected CNS lymphomas. Cytopathological examination of the CSF is still regarded as the 'gold standard' for the diagnosis of leptomeningeal malignant disease. However, cytopathology has only a low sensitivity in detecting leptomeningeal lymphoma involvement. Modern technologies including proteochemical and immunophenotypic studies by flow cytometry, and molecular genetic analyses of CSF may increase sensitivity and specificity, therefore, facilitating the diagnosis of CNS lymphomas. This review gives an overview and discussion of the current aspects of CSF analyses in CNS lymphomas.

Neoplastic meningitis: How MRI and CSF cytology are influenced by CSF cell count and tumor type

Background. Although CSF cytology and MRI are standard methods to diagnose neoplastic meningitis (NM), this complication of neoplastic disease remains difficult to detect. We therefore reevaluated the sensitivity of gadolinium (GD)-enhanced MRI and cerebrospinal-fluid (CSF)-cytology and the relevance of tumor type and CSF cell count. Methods. We retrospectively identified 111 cases of NM diagnosed in our CSF laboratory since 1990 with complete documentation of both MRI and CSF cytology. 37 had haematological and 74 solid neoplasms. CSF cell counts were increased in 74 and normal in 37 patients. Results. In hematological neoplasms, MRI was positive in 49% and CSF cytology in 97%. In solid tumors, the sensitivity of MRI was 80% and of cytology 78%. With normal CSF cell counts, MRI was positive in 59% (50% hematological, 72% solid malignancies) and CSF cytology in 76% (92% in hematological, 68% in solid neoplasms). In cases of elevated cell counts, the sensitivity of MRI was 72% (50% for hematological, 83% for solid malignancies) and of CSF cytology 91% (100% for haematological and 85% for solid neoplasms). 91% of cytologically positive cases were diagnosed at first and another 7% at second lumbar puncture. Routine protein analyses had a low sensitivity in detecting NM. Conclusions. The high overall sensitivity of MRI was only confirmed for NM from solid tumors and for elevated CSF cell counts. With normal cell counts and haematological neoplasms, CSF-cytology was superior to MRI. None of the analysed routine CSF proteins had an acceptable sensitivity and specificity in detecting leptomeningeal disease.

A systematic approach to the diagnosis of suspected central nervous system lymphoma

Central nervous system (CNS) lymphoma can present a diagnostic challenge. Currently, there is no consensus regarding what presurgical evaluation is warranted or how to proceed when lesions are not surgically accessible. We conducted a review of the literature on CNS lymphoma diagnosis (1966 to October 2011) to determine whether a common diagnostic algorithm can be generated. We extracted data regarding the usefulness of brain and body imaging, serum and cerebrospinal fluid (CSF) studies, ophthalmologic examination, and tissue biopsy in the diagnosis of CNS lymphoma. Contrast enhancement on imaging is highly sensitive at the time of diagnosis: 98.9% in immunocompetent lymphoma and 96.1% in human immunodeficiency virus-related CNS lymphoma. The sensitivity of CSF cytology is low (2%-32%) but increases when combined with flow cytometry. Cerebrospinal fluid lactate dehydrogenase isozyme 5, β2-microglobulin, and immunoglobulin heavy chain rearrangement studies have improved sensitivity over CSF cytology (58%-85%) but have only moderate specificity (85%). New techniques of proteomics and microRNA analysis have more than 95% specificity in the diagnosis of CNS lymphoma. Positive CSF cytology, vitreous biopsy, or brain/leptomeningeal biopsy remain the current standard for diagnosis. A combined stepwise systematic approach outlined here may facilitate an expeditious, comprehensive presurgical evaluation for cases of suspected CNS lymphoma.

Diagnosis of acute leukemia in cerebrospinal fluid (CSF-acute leukemia)

Cerebrospinal fluid-acute leukemia (CSF-acute leukemia) is a frequent and serious complication in patients with acute leukemia. One of the major problems of this complication is the diagnosis process itself. CSF cytology is currently considered the gold standard for establishing the diagnosis, a technique which presents various processing limitations, seriously impacting the predictive values. In the last 11 years, studies of CSF flow cytometry analysis done in patients with acute leukemia have demonstrated superiority in comparison with CSF cytology. Although comparative studies between these two techniques have been reported since 2001, no new consensus or formal changes to the gold standard have been established for the CSF acute leukemia diagnosis. The evidence suggests that positive flow cytometry cases, considered as indeterminate cases, will behave like disease in the central nervous system (CNS). Nevertheless, we think there are some variables and considerations that must be first evaluated under research protocols before CNS relapse can be established with only one positive flow cytometry analysis in the setting of indeterminate CSF samples. This paper proposes a diagnostic algorithm and complementary strategies.

Diagnostic strategies to investigate cerebrospinal fluid involvement in haematological malignancies

Central nervous system (CNS) involvement is a fatal complication of certain haematological malignancies with an incidence as high as 25% in specific leukaemia/lymphoma subtypes. It is often accompanied by 'occult' cerebrospinal fluid (CSF) involvement at diagnosis, which is frequently missed by conventional cytology examination. Unfortunately, a diagnostic gold standard is yet unavailable since CSF morphology may be negative for malignant cells in up to 45% of patients with suspected meningeal involvement. New technologies such as flow cytometry, molecular genetics and newer biomarkers may improve sensitivity and specificity facilitating the diagnosis of CNS involvement as well as effective prophylaxis and successful treatment.