Intraoperative dermoscopy features of subungual squamous cell carcinoma: a study of 53 cases.

BACKGROUND: Subungual squamous cell carcinoma (SU-SCC) is the most common malignant tumour of the nail unit. Intraoperative nail dermoscopy has been described only for pigmented tumours, onychomatricoma and glomus tumours. AIM: To establish a description of intraoperative dermoscopic features of SU-SCC. METHODS: A single-centre retrospective cohort of 53 SU-SCC cases over a 5-year period was reviewed by six examiners who individually scored 31 intraoperative dermoscopic features as present or absent. For each feature, the frequency and interobserver agreement was evaluated, then the data were compared and a consensus was reached. RESULTS: No feature had perfect or substantial interobserver agreement. Regarding anatomy and architecture, most tumours involved both the nail bed and nail matrix (n = 34, 64.2%) and had nonparallel lateral side edges (n = 36, 67.9%). Regarding vascular features, several different patterns were found: dotted vessels (n = 49, 92.5%), irregular vessels (n = 47, 88.7%), curved vessels (n = 46, 86.8%), sagittal vessels (n = 45, 84.9%), milky-red areas (n = 42, 79.2%), linear and regular vessels (n = 30, 56.6%), coiled and hairpin vessels (n = 23, 43.4%), and arborizing vessels (n = 16, 30.2%). Pigmented dermoscopy structures included dotted purpura, grey granulation and splinter haemorrhages, which were found in 49 (20.8%), 9 (17%) and 9 (17%) cases, respectively. Other dermoscopic signs were pink background, translucent structureless area, whitish scaly areas, distal plug, yellowish scales and dots, and 'digitiform' proximal edge, which were found in 49 (84.9%), 49 (84.9%), 43 (81.1%), 37 (69.8%), 28 (52.8%) and 22 (41.5%) cases, respectively. CONCLUSION: Analysis of this first large series of SU-SCC studied by intraoperative dermoscopy suggests that it gives useful information to better approach the diagnosis and to target biopsies.

Intraoperative dermoscopic features of onychomatricoma: a review of 10 cases.

BACKGROUND: Amelanotic nail tumours are difficult to diagnose. Dermoscopy is an accessible tool successfully used in diagnosis of amelanotic or melanotic skin tumours. We have previously shown the usefulness of dermoscopy in the preoperative diagnosis of onychomatricoma (OM). In this study, we completed this work by identifying additional intraoperative criteria to better establish the initial diagnosis of this tumour. AIMS: Evaluation of intraoperative dermoscopy in a small series of OM cases in order to define relevant diagnostic criteria. METHODS: In total, 10 patients with OM diagnosed in our centre were enrolled in the study. Six trained dermoscopists individually evaluated each criterion, then the data were compared and a consensus reached after discussion between the observers. For each criterion, we analysed its frequency and its interobserver accordance. We defined three architectural criteria (the 'Sagrada Familia' sign, digitations and the 'mirror sign'), and three vascular criteria (sagittal vessels, dotted vessels and irregular vessels). RESULTS: The Sagrada Familia sign, digitations and mirror sign were found in 100%, 90% and 70% of the cases, respectively, with high interobserver agreement. The vascular criteria were less regularly observed: sagittal, dotted and irregular vessels were respectively found in 80%, 70% and 50% of the OM cases, and were more difficult to assess, as shown by the lower interobserver agreement rates. CONCLUSION: Intraoperative dermoscopy of the nail matrix and bed offers useful information for the diagnosis and management of OM. Larger comparative studies should be performed to evaluate the true benefit of this approach.