Digital imaging of ink spot lentigo: Confocal microscopy and line‐field confocal optical coherence tomography assessment

Abstract

Dear Editor, The reticulated black solar lentigo was initially described by Bolognia et al. in 1992 as a type of solar lentigo. 1 Ink spot lentigo (ISL), as commonly known, clinically presents as a solitary dark pigmented macule with illdefined margins occurring on the back of fair skin individuals. Due to the peculiar appearance and the common association with multiple solar lentigos, ISL may be difficult to differentiate from melanoma. 1,2 Dermoscopy may show criteria similar to those observed in melanocytic lesions as an irregular thick pigment network, angulated lines and rhomboidal structures, and in these cases biopsy should be considered to rule out malignancy. 2,3 The use of noninvasive imaging techniques, like reflectance confocal microscopy (RCM), increases the diagnostic accuracy of equivocal skin lesions, allowing to obtain greater performances than dermoscopy alone. 4,5 A new digital tool, Line-field confocal optical coherence tomography (LC-OCT), is capable to acquire images/videos of skin lesions in multimodal view (vertical and horizontal), creating also immediate 3D cubes. 6 Pivotal studies reported promising preliminary data for the in vivo diagnosis of skin cancers. [6][7][8] We report RCM and LC-OCT morphological features of consecutive ISLs, correlating in vivo imaging to histopathology. Twenty-five histopathologically confirmed ISLs of 24 patients (14 M, 10 F, mean age: 48 years old, range: 19-82 years old) were investigated by RCM and LC-OCT from January 2023 to January 2024. ISLs were located on the trunk (10/25, 40%), on the face (7/25, 28%), on the lower extremities (4/25, 16%) and upper extremities (4/25, 16%). Dermoscopy showed atypical (thick, unevenly distributed) pigment network with sharp margins (23/25, 92%), and angulated lines (5/