Study Antigen targets Methodology Conventional diagnostic methods Diagnostic accuracy metrics Clinical utility Summary of main results Improvements in diagnostic accuracy or clinical decision-making
Nakano et al. [18] Collagen IV α chains Frozen sections of ameloblastoma, oral mucosa, and tooth germ samples stained with specific antibodies Histological examination (H&E staining) Not reported Collagen IV α chain distribution may serve as markers for ameloblastoma cytodifferentiation and progression Ameloblastoma expressed α1(IV), α2(IV), α5(IV), α6(IV) chains intensely around neoplastic epithelium, similar to oral mucosa.
α4(IV) expression was rare, mainly around nests of primitive tumour cells or potentially invasive sites.
Tooth germ showed stage- and position-specific collagen IV α chain distribution 		The study suggests collagen IV α chain distribution may be used as diagnostic markers to distinguish ameloblastoma from other lesions and assess tumour progression, but did not provide specific accuracy metrics.
Kolde et al. [19] Shaggy deposition of fibrinogen along the BMZ and/or IgM-positive cytoid-like bodies Dewaxed and rehydrated histological sections were treated with pronase E for antigen retrieval prior to IF staining Histological diagnosis and classification of OLP were made according to WHO criteria Sensitivity and specificity of IF staining patterns were calculated in comparison to histological diagnosis IF testing on pronase-treated histological sections improved the often controversial histopathological assessment of OLP Typical IF staining patterns of OLP (shaggy fibrinogen deposition, IgM-positive cytoid-like bodies) were found in 17 of the 30 biopsies. Immunofluorescence established the diagnosis of OLP in 6 out of 9 biopsies with histological alterations compatible but not evident for OLP The technique showed high sensitivity and specificity compared to histological diagnosis
Musa et al. [20] Fibrin, immunoglobulins, and C3 Staining of tissue samples for fibrin, immunoglobulins, and C3 and examination by fluorescence microscopy Clinical presentation, histopathology (H&E) Not explicitly reported, but comparison of DIF and histopathology findings DIF is valuable in establishing OLP diagnosis when histology is not conclusive, and in ruling out OLP when it is not present. However, DIF may misdiagnose some cases of dysplasia, carcinoma in situ, and SCC as OLP 75 cases were positive for OLP by both H&E and DIF, 65 cases were positive for OLP by DIF but not H&E, and 36 cases were suggestive of OLP by H&E but ruled out by DIF. Some cases of dysplasia, carcinoma in situ, and SCC were misdiagnosed as OLP by DIF DIF can improve diagnostic accuracy by detecting OLP cases missed by histopathology, and by ruling out OLP when not present. However, DIF has limitations and should be used in combination with histopathology to reach the final diagnosis
Kulthanan et al. [21] Deposits at the DEJ and CBs Frozen skin biopsy sections stained with fluorescein isothiocyanate-conjugated antibodies and examined under a fluorescence microscope Clinical and histologic examination Positive DIF yield in 75% of cases DIF may be helpful in disease differentiation, especially in cases with no specific clinical or histologic characteristics or ambiguous features Deposits at the DEJ and CBs were detected in 53% and 60% of cases, respectively. DEJ +CB deposits were found in 38% of cases. IgM +other immunoreactant deposits, including fibrin at the CBs, were found in 56% of cases. Shaggy fibrin deposition at the DEJ was found in 56% of cases, 44% of cases had immunoreactants other than fibrin deposited along the DEJ, which resembled those of LE DIF may help differentiate LP from other conditions, especially LE, in cases with no specific clinical or histologic characteristics or ambiguous features
Suresh et al. [22] Humoral antigens Gingival biopsy subjected to H&E and IF Conventional H&E microscopy in addition to DIF Conventional H&E microscopy in addition to DIF Clinical-pathologic correlation essential for definitive and differential diagnosis of DG cases Definitive diagnosis in 80% of gingival biopsies.Clinical diagnosis of lichen planus correlated with biopsy findings in 80% of cases, pemphigoid in 60% Negative DIF cases had significant pathology (dysplasia, carcinoma) missed on H&E alone
de Freitas Silva et al. [23] Twist, E-cadherin Immunohistochemistry, Western blotting, double-IF Histological grading of oral dysplasia based on WHO criteria Not reported Possible value of Twist and E-cadherin in predicting the risk of oral epithelium malignant transformation Significant differences in Twist and E-cadherin immunoexpression were observed between normal oral mucosa and OL, with an inverse relation since the earliest stages of oral dysplasia. Downregulation of E-cadherin was found to occur in a Twist-dependent manner in OSCC Twist and E-cadherin could be used as potential markers to predict the risk of malignant transformation in oral epithelium, but does not provide specific data on diagnostic accuracy
Rameshkumar et al. [24] Not specified Review of clinical features and histopathology (H&E) of 70 subjects; Histopathology (H&E) and DIF performed on biopsy specimens from 12 subjects Clinical features, histopathology Consistency between histopathology and DIF in the prospective analysis (66% cases) DIF can improve diagnostic efficiency of oral mucocutaneous lesions when used in addition to clinical and histopathological evaluation Retrospective analysis showed similar findings to previous studies except for some differences; prospective analysis, histopathology and DIF were consistent in 66% cases DIF can enhance diagnostic accuracy when used along with clinical and histopathological evaluation for oral mucocutaneous lesions
Hashimoto et al. [25] C3 deposition in BMZ Oral mucosal biopsy, immunoserological tests (IIF, immunoblotting, ELISA) Clinical, histopathological assessments Not reported Granular C3 deposition in oral BMZ may be a characteristic feature of severe OLP 10 out of 12 cases showed granular C3 deposition in oral BMZ on DIF. The 10 cases showed no positive reactivity for IgG or IgA antibodies DIF for C3 deposition may provide additional diagnostic information for severe cases of OLP
Montague et al. [26] Fibrinogen Diagnostic codes, recorded age, gender, diagnosis, DIF findings, and biopsy location; re-examined H&E slides to confirm diagnosis Clinical and histopathologic examination Characterizing fibrinogen positivity in premalignant and malignant oral lesions Fibrinogen positivity on DIF may contribute to diagnostic confusion, especially in cases with mild or reactive premalignant features 68 out of 164 cases showed fibrinogen positivity. Low-grade dysplasia and verrucous lesions made up the majority of fibrinogen positive cases. A lichenoid distribution of the inflammatory infiltrate significantly predicted fibrinogen positivity Fibrinogen positivity may be seen in premalignant and malignant oral lesions, increasing the risk of misdiagnosis
Lee [27] Fibrinogen deposition at the mucosal-submucosal interface Modified WHO diagnostic criteria for OLP and OLL, and criteria proposed by AAOMP. DIF results were evaluated for deposition intensity or pattern of fibrinogen and classified as positive, possibly positive or negative Clinical and histologic assessment Not provided Final diagnosis of OLP could be different depending on the type of diagnostic criteria used. There was no statistical difference in DIF findings between OLP and OLL Patients diagnosed as OLP were slightly more when using the modified WHO criteria compared to the AAOMP criteria. There was no statistical difference in DIF between OLP and OLL when applying either the modified WHO or AAOMP criteria Highlights the potential for variability in the final diagnosis of OLP and OLL depending on the diagnostic criteria used, and suggests that DIF may not provide additional diagnostic value in differentiating between these two conditions

ACIF = anticomplement immunofluorescence; ANA = antinuclear antibody; BMZ = basement membrane zone; C3 = complement component 3; CB = cytoid bodies; DIF = direct immunofluorescence; DG = desquamative gingivitis; Dsg1 = desmoglein 1; Dsg3 = desmoglein 3; H&E = hematoxylin and eosin; HGD = high-grade dysplasia; IIF = indirect immunofluorescence; IgG = immunoglobulin G; IgA = immunoglobulin A; IgM = immunoglobulin M; LE = lupus erythematosus; LGD = low-grade dysplasia; MMP = mucous membrane pemphigoid; MMO = maximum mouth opening; OLDR = oral lichenoid dysplasia; OLL = oral lichenoid lesions; OLP = oral lichen planus; OMLP = oral mucosal lichen planus; OSCC = oral squamous cell carcinoma; OSF = oral submucous fibrosis; PV = pemphigus vulgaris; RAS = recurrent aphthous stomatitis; T1 = tumour size classification (smallest); T4 = tumour size classification (largest); ELISA = enzyme-linked immunosorbent assay; HCV = hepatitis C virus; SCC = squamous cell carcinoma; IF = immunofluorescence.