Desquamative Gingivitis (DG) comprises heterogeneous clinical manifestations of numerous immune-mediated muco-cutaneous diseases. Optical Coherence Tomography (OCT) has been proposed as a valuable diagnostic support even if, to date, there are no standardized OCT-diagnostic patterns applicable to DGs. A systematic review was performed to detect existing data on in vivo OCT diagnostic patterns of the most common immune-mediated DGs (i.e., pemphigus vulgaris, mucous membrane pemphigoid and oral lichen planus). It has been found that OCT exhibits specific patterns that address the diagnosis of DG by pemphigus vulgaris (i.e., intraepithelial unilocular blister, reduced epithelial thickness, presence of acantholytic cells in the blister) and by mucous membrane pemphigoid (i.e., subepithelial multilocular blister, presence of inflammatory infiltrate), but not by oral lichen planus. These patterns could offer an attractive diagnostic OCT framework to support the clinical preliminary assessment and monitoring of these complex pathological conditions.