Reflectance Confocal Microscopy Characteristics
Reflectance confocal microscopy (RCM) images show a well-defined,
hyper-refractile lesion at the center of the image (Figure 2 ).
Honeycomb pattern and small bright cells and large bright dendritic
cells can be seen in the epidermis. Edged papillae at the level of the
dermal epidermal junction can be seen surrounding a central, homogeneous
area. A lobule of polygonal, interconnected cells, likely epithelial
cells distinct from surrounding keratinocytes, can be seen in the dermis
at the inferior margin of the lesion. Superior margin shows polycyclic
rings representing dermal epidermal junction, surrounding and overlying
a homogenous refractile area (Figure 2C ). The RCM features are
suggestive of a metastatic tumor, as it lacks features of a squamous
cell carcinoma, basal cell carcinoma, melanocytic tumor and other
epithelial infiltrates. Other epithelial infiltrates such as
sarcoidosis, foreign body granulomas and lymphomas can also be excluded.
For example, sarcoidosis will have large macrophages which will be
visualized under RCM which this case lacks. Foreign body granuloma can
be excluded as there is no evidence of foamy/multinucleated giant cells
surrounded by fibrous response. Lymphoma can be excluded as there is no
evidence of lymphocytes that are visible as hyperreflective bright cells
with high density.