Correlation between reflectance confocal microscopy features and horizontal histopathology in cutaneous squamous cell carcinoma in situ: A case series

Correlation Between In Vivo Reflectance Confocal Microscopy and Horizontal Histopathology in Skin Cancer: A Review

“…The detection of “red dots”, representing glomerular vessels in the superficial dermis, is the most typical dermoscopic finding of SCCis ( 18 ). In addition, RCM has been also validated as useful diagnostic tool and its application in the dermatological practice has been supported by the perfect matching with HHS found by our research group ( 14 ). SCCis shows the following RCM features ( 14 ) ( Figures 1A, C ): i) at the level of stratum corneum, highly refractive amorphous structures and sporadically polygonal, nucleated cells; ii) at the level of the stratum granulosum/spinosum, marked architectural disarray, consisting of keratinocytes highly variable in size, shape, and nuclear morphology; scattered bright dendritic cells may also be found; iii) at the level of the dermoepidermal junction, large rounded dark areas, corresponding to enlarged dermal papillae.…”

“…Squamous cell carcinoma in situ (SCCis) represents the earliest and non-invasive form of squamous cell carcinoma, in which, by definition, the neoplastic cells do not infiltrate the basement membrane and therefore lack distant metastatic potential ( 14 ). SCCis mainly affects photoexposed skin of elderly, and the head and neck are the most commonly affected sites ( 14 ).…”

“…Squamous cell carcinoma in situ (SCCis) represents the earliest and non-invasive form of squamous cell carcinoma, in which, by definition, the neoplastic cells do not infiltrate the basement membrane and therefore lack distant metastatic potential ( 14 ). SCCis mainly affects photoexposed skin of elderly, and the head and neck are the most commonly affected sites ( 14 ). Clinically, SCCis arises in the form of flat/raised, reddish/brownish in color, often scaly, papules or plaques; due to the low specificity of the clinical presentation, further non-invasive diagnostic tools, such as dermoscopy and RCM, are often required to enhance the diagnostic accuracy of SCCis ( 14 , 18 ).…”

“…SCCis mainly affects photoexposed skin of elderly, and the head and neck are the most commonly affected sites ( 14 ). Clinically, SCCis arises in the form of flat/raised, reddish/brownish in color, often scaly, papules or plaques; due to the low specificity of the clinical presentation, further non-invasive diagnostic tools, such as dermoscopy and RCM, are often required to enhance the diagnostic accuracy of SCCis ( 14 , 18 ). The detection of “red dots”, representing glomerular vessels in the superficial dermis, is the most typical dermoscopic finding of SCCis ( 18 ).…”

“…SCCis shows the following RCM features ( 14 ) ( Figures 1A, C ): i) at the level of stratum corneum, highly refractive amorphous structures and sporadically polygonal, nucleated cells; ii) at the level of the stratum granulosum/spinosum, marked architectural disarray, consisting of keratinocytes highly variable in size, shape, and nuclear morphology; scattered bright dendritic cells may also be found; iii) at the level of the dermoepidermal junction, large rounded dark areas, corresponding to enlarged dermal papillae. Horizontal histopathology perfectly matches with the previous reported RCM findings ( 14 ) ( Figures 1B, D ): hyperkeratosis and parakeratosis are the histopathological causes of the refractive amorphous structures and the nucleated cells observed in the stratum corneum at RCM; the loss of architectural array visible in the stratum granulosum/spinosum at RCM reflects the presence of atypical keratinocytes with nuclei of variable size and shape along the entire thickness of epidermis; some S-100 positive, CD1a negative and Melan-A negative dendritic cells may be occasionally found scattered among the neoplastic cells; lastly, at the dermoepidermal junction, HHSs show enlarged dermal papillae containing glomeruloid capillary vessels, corresponding both to the rounded dark areas and to the “red dots” observed at RCM and dermoscopy, respectively. Since the horizontal histopathology does not allow to evaluate the possible presence of dermal invasion, the concept that its use is only for the purpose of comparing it with the RCM findings, in order to further validate the diagnostic use of RCM, must be emphasized.…”