Table 2.
Reflectance Confocal Microscopy (RCM) Findings in Actinic Keratosis and Squamous Cell Carcinoma and Their Histopathological Correlations [9,15]
| Level/Features | Description | Histopathological Correlation |
|---|---|---|
| Stratum corneum | ||
| Scale | White refractile amorphous material | Increase of thickness of stratum corneum |
| Parakeratosis | Individual highly refractile round cells with a hyporefractile visible nucleus | Parakeratotic cells |
| Epidermis spinous stratum | ||
| Atypical honeycomb pattern | Irregular size and shape of cells with variable thickness and brightness of the lines | Abnormal pattern of the spinous layers |
| Targetoid cells | Cells with a refractile nucleus, hyporefractile periphery, and refractile membrane (target-like) | Apoptotic large cells |
| Epidermis spinous-granular layers | ||
| Disarranged and disrupted epidermal pattern | Severe architectural disarray in which the honeycomb pattern is no longer visible | Epidermis spinous-granular layers |
| Epidermis (full thickness) | ||
| Atypical honeycomb pattern | Irregular honeycomb also affecting the stratum granulosum | Cellular atypia affecting the complete epidermal layers |
| Dermoepidermal junction | ||
| Thickened papillae | Enhanced honeycomb surrounding the dermal papillae | Atypical hyperplasia of the basal epidermal layer surrounding the dermal papilla |
| Dermis | ||
| Dermal elastosis | Curled and clumped fibers in upper dermis and slightly small dilated vessels | Dermal elastosis |
| Round blood vessels | Dilated blood vessels within the dermal papillae that run perpendicular to the horizontal RCM plane of imaging (S-shaped vessels) | Neovascularization |
| Irregular and hairpin vessels | Atypical and marked dilated loop vessels surrounding refractile tumor nests | Neovascularization |