Comparison of morphologic criteria for actinic keratosis and squamous cell carcinoma using in vivo multiphoton tomography.

The routine diagnostic procedure of actinic keratosis (AK) and invasive squamous cell carcinoma (SCC) is a histological examination after taking a biopsy. In the past decades, non-invasive optical methods for skin examination have been developed. Patients with clinical diagnosis of AK or SCC were examined. The morphological criteria were determined for healthy, AK and SCC skin and compared for statistically significant differences. In this study, the applicability of multiphoton tomography (MPT) as an in vivo diagnostic tool for AK and SCC was evaluated. Changes in the morphology of the keratinocytes such as broadened epidermis, large intercellular spaces, enlarged nucleus and a large variance in cell shape could easily be recognized. The cell nuclei of AK and SCC were significantly larger compared to healthy skin cells in all cell layers. The nucleus-cytoplasm ratio was also significantly higher for AK and SCC than for the healthy skin cells. It was even higher in SCC compared to spinous and basal cell layer of AK. The cell density in AK and SCC was significantly lower than in the basal and spinous cell layers of healthy skin. In SCC, the cell density was significantly lower than in AK. Concerning the intercellular spaces, significant differences were found for AK and healthy skin in spinous and basal cell layer and for SCC compared to AK and healthy skin. In this study, MPT proved to be a valuable non-invasive imaging method for in vivo detection and discrimination of AK and SCC from healthy skin.

In vivo detection of basal cell carcinoma: comparison of a reflectance confocal microscope and a multiphoton tomograph.

The standard diagnostic procedure for basal cell carcinoma (BCC) is invasive tissue biopsy with time-consuming histological examination. To reduce the number of biopsies, noninvasive optical methods have been developed providing high-resolution skin examination. We present direct comparison of a reflectance confocal microscope (RLSM) and a multiphoton tomograph (MPT) for BCC diagnosis. Both systems are applied to nine patients prior to surgery, and the results are analyzed, including histological results. Both systems prove suitable for detecting typical characteristics of BCC in various stages. The RLSM allows large horizontal overview images to be obtained, enabling the investigator to find the regions of interest quickly, e.g., BCC nests. Elongated cells and palisading structures are easily recognized using both methods. Due to the higher resolution, changes in nucleus diameter or cytoplasm could be visualized with the MPT. Therefore, the nucleus diameter, nucleus/cytoplasm ratio, and cell density are estimated for normal and BCC cells using the MPT. The nucleus of elongated BCC cells is significantly longer than other measured normal skin cells, whereas the cell density and nucleus/cytoplasm ratio of BCC cannot be significantly distinguished from granular cells.