Assessment of tumor thickness in melanocytic skin lesions: comparison of optical coherence tomography, 20-MHz ultrasound and histopathology.

ABSTRACT

BACKGROUND: Accurate assessment of vertical tumor size is important for surgical treatment planning of melanocytic skin lesions. High-frequency ultrasound (HFUS) is frequently used for this purpose, but overestimation of tumor thickness is known as a problem especially in thin melanocytic lesions. Optical coherence tomography (OCT) as a new imaging technique might be a promising alternative. OBJECTIVE: To evaluate the ability of OCT to accurately determine the vertical tumor thickness of melanocytic skin lesions and to compare it with HFUS and histopathology in order to improve surgical planning. METHODS: In this single-center study, 26 melanocytic lesions were imaged by OCT and HFUS. Vertical lesion dimensions of both methods were compared with histopathological measurements. RESULTS: Bland-Altman plots for OCT and histopathology as well as for HFUS and histopathology revealed better agreement for OCT and histopathology concerning tumor thickness measurements. Tumor thickness values for the melanocytic lesions measured by OCT presented a median tumor thickness of 0.31 mm (range 0.10-0.77) compared to a median tumor thickness of 0.25 mm (range 0.06-1.5) measured by histopathology. The median tumor thickness of HFUS was 0.44 mm (range 0.23-1.1). A Spearman correlation procedure including the correlation coefficient (r) showed a stronger relationship between OCT and histopathology (r = 0.734) compared to HFUS and histopathology (r = 0.390). CONCLUSIONS: On the basis of this smaller study cohort, OCT seems to be more exact than HFUS as far as thickness determination of thin melanocytic skin lesions is concerned.