Detection of BRAF mutation in metastatic melanoma utilizing cell-transferred cytological smears

Cytologic diagnosis of metastatic melanoma by FNA: A practical review

Malignant melanoma (MM) is a highly aggressive neoplasm with a growing worldwide incidence. It is not uncommon that the disease is already metastatic at the time of the first diagnosis. Regional lymph nodes and skin are the first and most common metastatic sites, followed by distant visceral sites (lungs, liver, and central nervous system) and bone. In this clinical setting, fine-needle aspiration (FNA) often represents the first diagnostic approach. FNA is a useful tool to obtain a rapid and accurate diagnosis, in conjunction with ancillary techniques and molecular analysis, as recommended by recent guidelines. The aim of this review was to describe the cytomorphology, immunocytochemical tools, and molecular tools used for the diagnosis of MM metastases on FNA.

Predictive Evaluation on Cytological Sample of Metastatic Melanoma: The Role of BRAF Immunocytochemistry in the Molecular Era

BACKGROUND

Cutaneous malignant melanoma is an aggressive neoplasm. In advanced cases, the therapeutic choice depends on the mutational status of BRAF. Fine needle aspiration cytology (FNA) is often applied to the management of patients affected by melanoma, mainly for the diagnosis of metastases. The evaluation of BRAF mutational status by sequencing technique on cytological samples may be inconvenient, as it is a time and biomaterial-consuming technique. Recently, BRAF immunocytochemistry (ICC) was applied for the evaluation of BRAF V600E mutational status. Although it may be useful mainly in cytological samples, data about BRAF ICC on cytological samples are missing.

METHODS

We performed BRAF ICC on a series of 50 FNA samples of metastatic melanoma. BRAF molecular analysis was performed on the same cytological samples or on the corresponding histological samples. Molecular analysis was considered the gold standard.

RESULTS

BRAF ICC results were adequate in 49 out of 50 (98%) cases, positive in 15 out of 50 (30%) cases and negative in 34 out of 50 (68%) of cases. Overall, BRAF ICC sensitivity, specificity, positive predictive value and negative predictive value results were 88.2%, 100%, 100% and 94.1%, respectively. The diagnostic performance of BRAF ICC results was perfect when molecular evaluation was performed on the same cytological samples. Hyperpigmentation represents the main limitation of the technique.

CONCLUSIONS

BRAF ICC is a rapid, cost-effective method for detecting BRAF V600E mutation in melanoma metastases, applicable with high diagnostic performance to cytological samples. It could represent the first step to evaluate BRAF mutational status in cytological samples, mainly in poorly cellular cases.

[Cytologic control of the resection margins of hemispheric gliomas and metastases]

INTRODUCTION

Postoperative MRI is the conventional method for assessing the radicalness of hemispherical tumors excision, but the method has limitations on sensitivity in the assessment of tumor infiltration of the peritumoral zone. The 'gold standard' for detecting tumor cells is the microscopic visualisation.

AIM

To study the possibilities of a cytological study of the excision margins of glial and metastatic tumors for an objective assessment of the radical nature of the operation.

MATERIAL AND METHODS

The study included 35 patients with intracerebral tumors who underwent open surgery at a university clinic of Volga Research Medical University in 2018-2019: 15 patients with metastasis, 13 patients with MRI-contrasting gliomas Grade III-IV and 7 patnents with non-MRI-contrasting gliomas Grade II-III. During the surgery, samples for cytological examination were taken from the following sites: from the tumor, from the nearest perifocal zone, and at a distance of 5-7 mm, along the border of the extended resection. 154 samples were examined: from 2 to 5 for each patient.

RESULTS

The data on the radicalness of the operation, obtained by methods of cytological analysis of the resection margins and postoperative MRI, are not only consistent (p=0.001), but also complement each other, in particular, in some cases, tumor cells were found even in those areas where the tumor tissue was not detected with MRI. In cases of cerebral metastases excision, tumor cells in the nearest perifocal zone were found in 8 out of 28 samples (28.6%), at the extended resection margins - in 3 out of 29 (10.3%). In cases of resection of MRI-contrasting gliomas Grade III-IV, tumor cells in the nearest perifocal zone were found in 22 out of 32 samples (68.8%), at the extended resection margins - in 14 out of 20 (70%). In cases of excision of diffuse gliomas Grade II-III, tumor cells in the nearest perifocal zone were found in 10 out of 17 samples (58.9%), at the extended resection margins - in 4 out of 11 (36.4%).

CONCLUSION

The first data obtained demonstrated sufficient informativeness of the cytologic examination of the peritumoral zone as an additional tool for assessing the radicalness of glioma and metastasis surgery. Cytologic analysis of the perifocal zone shows that the extension of the borders of the removal of Grade III-IV gliomas has no advantages, because tumor cells were found both in the nearest perifocal zone and at the extended resection margins with with approximately the same frequency.

Overview of Molecular Testing of Cytology Specimens

OBJECTIVE

Utilizing cytology specimens for molecular testing has attracted increasing attention in the era of personalized medicine. Cytology specimens are clinically easier to access. The samples can be quickly and completely fixed in a very short time of fixation before tissue degradation occurs, compared to hours or days of fixation in surgical pathology specimens. In addition, cytology specimens can be fixed without formalin, which can significantly damage DNA and RNA. All these factors contribute to the superb quality of DNA and RNA in cytology specimens for molecular tests.

STUDY DESIGN

We summarize the most pertinent information in the literature regarding molecular testing in the field of cytopathology.

RESULTS

The first part focuses on the types of cytological specimens that can be used for molecular testing, including the advantages and limitations. The second section describes the common molecular tests and their clinical application.

CONCLUSION

Various types of cytology specimens are suitable for many molecular tests, which may require additional clinical laboratory validation.

Utilization of Cell-Transfer Technique for Molecular Testing on Hematoxylin-Eosin–Stained Sections: A Viable Option for Small Biopsies That Lack Tumor Tissues in Paraffin Block

Context.—

In some instances the standard method of doing molecular testing from formalin-fixed, paraffin-embedded block is not possible because of limited tissue. Tumor cell–enriched cell-transfer technique has been proven useful for performing immunocytochemistry and molecular testing on cytologic smears.

Objective.—

To establish the cell-transfer technique as a viable option for isolating tumor cells from hematoxylin-eosin (H&E)–stained slides.

Design.—

Molecular testing was performed by using the cell-transfer technique on 97 archived H&E-stained slides from a variety of different tumors. Results were compared to the conventional method of molecular testing.

Results.—

Polymerase chain reaction–based molecular testing via the cell-transfer technique was successfully performed on 82 of 97 samples (85%). This included 39 of 47 cases for EGFR, 10 of 11 cases for BRAF, and 33 of 39 cases for KRAS mutations. Eighty-one of 82 cell-transfer technique samples (99%) showed agreement with previous standard method results, including 4 mutations and 35 wild-type alleles for EGFR, 4 mutations and 6 wild-type alleles for BRAF, and 11 mutations and 21 wild-type alleles for KRAS. There was only 1 discrepancy: a cell-transfer technique with a false-negative >KRAS result (wild type versus G12C).

Conclusions.—

Molecular testing performed on H&E-stained sections via cell-transfer technique is useful when tissue from cell blocks and small surgical biopsy samples is exhausted and the only available material for testing is on H&E-stained slides.