Significance: Sentinel lymph node (SLN) biopsy is an important method for metastasis staging in, e.g., patients with malignant melanoma. Tools enabling prompt histopathological analysis are expected to facilitate diagnostics; optical technologies are explored for this purpose. Aim: The objective of this exploratory study was to investigate the potential of adopting multiphoton laser scanning microscopy (MPM) together with fluorescence lifetime analysis (FLIM) for the examination of lymph node (LN) tissue ex vivo. Approach: Five LN tissue samples (three metastasis positive and two negative) were acquired from a biobank comprising tissues from melanoma patients. Tissues were deparaffinized and subjected to MPM-FLIM using an experimental MPM setup equipped with a time correlated single photon counting module enabling FLIM. Results: The data confirm that morphological features similar to conventional histology were observed. In addition, FLIM analysis revealed elevated morphological contrast, particularly for discriminating between metastatic cells, lymphocytes, and erythrocytes. Conclusions: Taken together, the results from this investigation show promise for adopting MPM-FLIM in the context of SLN diagnostics and encourage further translational studies on fresh tissue samples.

The diagnosis of genital lichen sclerosus (LS) is often confirmed by obtaining a skin biopsy, which can lead to unwanted complications and is uncomfortable in the sensitive genital area. Thus, there is a need of finding novel, non-invasive techniques that can rapidly and accurately diagnose LS. The present study investigated the potential for reflectance confocal microscopy (RCM) to diagnose LS compared with healthy penile skin and other common penile skin disorders in males. A total of 30 male patients, including patients with LS, nonspecific balanoposthitis, plasma cell balanitis and psoriasis, and healthy individuals were included and were subject to non-invasive RCM investigation. Prominent fiber-like structures, representing hyaline sclerosis, were observed in the RCM images for almost half of the patients. Differences between healthy penile skin and LS were confirmed by identifying the edged papillae on healthy skin and their absence or obscureness in patients with LS. Notably, RCM could detect the atypical honeycomb pattern referring to dysplasia in 1 patient with LS with penile intraepithelial neoplasia. In conclusion, the present study demonstrated that RCM can detect sclerosis in penile LS. RCM can potentially become a valuable tool for monitoring patients with LS for dysplasia providing a useful non-invasive diagnostic tool for genital disorders.

A descriptive study exploring the potential of multiphoton microscopy for sentinel lymph node diagnostics in melanoma, which reveals cell morphology characteristics in tissue from lymph node metastasis. Future studies are encouraged to promote translational implementation.

Development of non-invasive techniques for early stage diagnostics of melanoma metastasis is great importance to improve survival rates. Multiphoton microscopy together with fluorescence lifetime imaging is here explored for finding metastasis in lymph node tissues.

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