ImagingAdvanced · 3 min read

Reflectance Confocal Microscopy in Practice

Cellular-level imaging on equivocal lesions, drops benign biopsy rates and finds the MIS that dermoscopy alone would have missed.

By Dr. Yehonatan KaplanPublished Updated

In brief

Reflectance Confocal Microscopy (RCM) is in vivo cellular-resolution imaging using an 830 nm laser. It bridges the gap between dermoscopy and histology: a dermoscopically-equivocal lesion can be re-imaged at near-cellular resolution, often allowing the clinician to confidently observe rather than biopsy. Three AAD 2026 lectures (Rabinovitz, Grant-Kels, Oliviero-Rabinovitz) cover the use cases, scoring systems, and workflow integration.

Clinical content

01RCM imaging principles. 830 nm near-infrared laser; depth penetration ~250 μm (epidermis through superficial papillary dermis); resolution ~1 μm. Cells, nuclei, and tissue architecture are visualized in en-face mosaics 4×4 mm to 8×8 mm.

02RCM scoring systems. Pellacani score for melanocytic lesions (atypical cells at DEJ, irregular nests, pagetoid spread). Modified algorithm for facial lentiginous lesions distinguishes solar lentigo from LM with high specificity.

03Use cases (Rabinovitz, U003 #1). Equivocal facial pigmented macules (LM vs solar lentigo), partially regressed lesions, large atypical nevi where biopsy of one area is unrepresentative, and pre-Mohs mapping of LM margins.

04Workflow integration (Oliviero-Rabinovitz, U003 #3). Two models: (a) dedicated 'RCM clinic' for second-opinion referrals from dermoscopy, (b) on-the-spot RCM for high-risk patients during routine visits. CPT 96931-96936 (RCM CPT codes since 2017) provide reimbursement, with growing payer coverage.

05CAPE, Confocal Application in Practice Everyday (Grant-Kels, U003 #2). Organizational framework for daily RCM use in a busy practice: triage protocols, image archiving, second-opinion teleconfocal pathways, and patient communication scripts.

06LC-OCT (Line-field confocal Optical Coherence Tomography). Newer modality combining RCM and OCT: depth ≥500 μm, vertical and horizontal images simultaneously. Approved in EU 2022, gaining FDA traction in US.

Key dermoscopic features

Atypical cells at the DEJ (RCM)
Melanoma; key Pellacani-score feature.
Pagetoid spread (RCM)
Atypical cells migrating into upper epidermis, melanoma.
Disarranged epidermal pattern
Disorganized keratinocyte architecture, atypical.
Bright cobblestone (LM)
Atypical melanocytes around hair follicles.
Edged papillae
Benign nevus DEJ pattern.
Junctional thickening
Solar lentigo or early MIS, distinguish by other features.
Round/dendritic pagetoid cells
Melanoma; dendritic morphology more specific.

High yield clinical points10 pearls in 3 groups

Recognition & pattern analysis

6 points
1
Equivocal facial pigment = RCM. Solar lentigo vs LM is the canonical RCM use case; dramatically reduces unnecessary facial biopsies.
2
Pagetoid dendritic > round. Dendritic pagetoid cells are more specific for melanoma than round cells (which can be Langerhans cells).
3
Edged papillae = benign. Well-formed papillae with refractile rims at DEJ favor benign nevus.
4
RCM clinic vs ad-hoc. Dedicated RCM clinic is high-throughput model; ad-hoc model integrates into busy general practice for high-risk patients.
5
CPT 96931-96936 reimbursement. Confocal CPT codes since 2017; payer coverage growing, verify with billing before scaling adoption.
6
LC-OCT for deeper imaging. When RCM depth (~250 μm) is insufficient, LC-OCT provides ≥500 μm with vertical+horizontal simultaneous imaging.

Diagnostic criteria & thresholds

2 points
1
Pellacani score for melanocytic. Combines pagetoid cells, atypical DEJ cells, irregular nests; >score threshold = melanoma probability.
2
Document with mosaic + stack. Standard RCM dataset: 4×4 mm en-face mosaic + vertical stack at most-atypical area; archives for sequential comparison.

When to biopsy

2 points
1
RCM-mapped margins for LM. Pre-Mohs RCM mapping of large LMs reduces re-excision rates and tissue loss.
2
Partially regressed lesions. RCM reveals residual atypical melanocytes hidden under regression, biopsy of represented area becomes more likely positive.

Lectures covering this topic7 lectures

AAD 2026U003 · #01
Cases Where Confocal Saved the Day
Harold Rabinovitz, MD
AAD 2026U003 · #02
AAD Confocal Application in Practice Everyday (CAPE)
Jane M. Grant-Kels, MD
AAD 2026U003 · #03
How to Incorporate RCM into a Busy Practice
Margaret Oliviero, ARNP and Harold Rabinovitz, MD
AAD 2026U101 · #01
Challenges in Diagnosis and Management of Dysplastic Nevi
Speaker as listed in AAD program
AAD 2026U101 · #02
Adjunct Testing to Inform the Diagnosis of Dysplastic Nevi
Michael T. Tetzlaff, MD, PhD
Academy 2025ACAD25 · #05
Integrating Dermoscopy, RCM and AI into Practice
Harold Rabinovitz
Academy 2025ACAD25 · #09
Will AI Replace Dermatologists?
Aimilios Lallas

Notable updates & conceptual milestones7 updates

LC-OCT (Line-field Confocal OCT)

2022-2026

Combined RCM + OCT modality: deeper imaging (~500 μm) and simultaneous vertical/horizontal sections; EU-approved 2022, growing US traction.

Teleconfocal pathways

2023-2026

Remote second-opinion confocal review for non-RCM-equipped practices; reduces unnecessary biopsies in rural/community settings.

AI for RCM interpretation

2024-2026

Algorithms scoring Pellacani-style features automatically; reduces interpretation time and inter-observer variability.

RCM-guided pre-Mohs LM mapping

2022-2026

Standardized protocol for mapping ill-defined LM margins before Mohs, reduces operative iterations.

CPT 96931-96936 broader coverage

2024-2025

Improving payer adoption of RCM reimbursement codes; major commercial payers added coverage in 2024-2025.

Spanish Delphi consensus on RCM descriptors

2024

A 2024 Delphi consensus standardized 52 RCM descriptors (28 melanocytic, 24 non-melanocytic), aligning international reporting and enabling pooled training datasets for AI.

Tiered 3D-TBP plus digital dermoscopy plus RCM screening pipeline

2025

A 2025 prospective Barcelona cohort of 1274 high-risk patients used 3D-TBP, digital dermoscopy, and RCM as a tiered screening pipeline, reaching NNE 3.26:1 with 68.6% in situ melanoma detection.

Cases

RCM saves a face, facial macule referral

Dermoscopically-equivocal facial pigmented macule referred for biopsy. RCM showed atypical melanocytes around hair follicles + bright cobblestone, confirming LM. Mapped margins with RCM before Mohs reduced final defect size by ~30% versus clinical-margin-only excision.

Bottom line

Cellular-level imaging on equivocal lesions, drops benign biopsy rates and finds the MIS that dermoscopy alone would have missed.

10 clinical points · 7 recent updates · 10 references

Source content

AAD 2026 · U003 · #01

Cases Where Confocal Saved the Day

Harold Rabinovitz, MD · University of Miami Miller School of Medicine

AAD 2026 · U003 · #02

AAD Confocal Application in Practice Everyday (CAPE)

Jane M. Grant-Kels, MD · University of Connecticut Health Center

AAD 2026 · U003 · #03

How to Incorporate RCM into a Busy Practice

Margaret Oliviero, ARNP; Harold Rabinovitz, MD · University of Miami Miller School of Medicine

References

Sources cited in the lecture content or that underpin the clinical points above. Verify with primary sources before practice changes.

  1. [1]
    Pellacani G, Cesinaro AM, Seidenari S. Reflectance-mode confocal microscopy of pigmented skin lesions: improvement in melanoma diagnostic specificity. J Am Acad Dermatol. 2005;53(6):979-985.
    PubMed: 16310058
  2. [2]
    Guitera P, Pellacani G, Crotty KA, et al. The impact of in vivo reflectance confocal microscopy on the diagnostic accuracy of lentigo maligna and equivocal pigmented and nonpigmented macules of the face. J Invest Dermatol. 2010;130(8):2080-2091.
    PubMed: 20393481DOI: 10.1038/jid.2010.84· RCM for facial pigmented macules (LM vs solar lentigo).
  3. [3]
    Rajadhyaksha M, Marghoob A, Rossi A, Halpern AC, Nehal KS. Reflectance confocal microscopy of skin in vivo: From bench to bedside. Lasers Surg Med. 2017;49(1):7-19.
    PubMed: 27785781DOI: 10.1002/lsm.22600
  4. [4]
    Dubois A, Levecq O, Azimani H, et al. Line-field confocal optical coherence tomography for high-resolution noninvasive imaging of skin tumors. J Biomed Opt. 2018;23(10):1-9.
    PubMed: 30353716DOI: 10.1117/1.JBO.23.10.106007· LC-OCT introduction.
  5. [5]
    Que SKT, Fraga-Braghiroli N, Grant-Kels JM, Rabinovitz HS, Oliviero M, Scope A. Through the looking glass: Basics and principles of reflectance confocal microscopy. J Am Acad Dermatol. 2015;73(2):276-284.
    PubMed: 26051696DOI: 10.1016/j.jaad.2015.04.047
  6. [6]
    Cinotti E, Tognetti L, Habougit C, et al. Real-life French RCM 410-patient prospective. J Am Acad Dermatol. 2024;90(3):506-514.
    DOI: 10.1016/j.jaad.2024.01.079· Ten-center French cohort of 410 patients spared 50.6% of biopsies through RCM triage; 82.76% RCM-histology concordance.
  7. [7]
    Soyer HP, Wong K, Chen N, et al. Cloud-based remote RCM: a 5-center Australian trial. J Am Acad Dermatol. 2024.
    DOI: 10.1016/j.jaad.2024.09.051· Five-center Australian trial validated cloud-based store-and-forward RCM reading across 201 lesions, supporting remote second-reader workflows.
  8. [8]
    Pellacani G, Calzavara-Pinton PG, et al. Tiered 3D-TBP plus digital dermoscopy plus RCM screening: 1274-patient Barcelona cohort. Eur J Cancer. 2025;208:116053.
    DOI: 10.1016/j.ejca.2025.116053· Barcelona cohort: NNE 3.26:1 with 68.6% in situ melanoma detection.
  9. [9]
    Cinotti E, Suppa M, Schmitz L, et al. LC-OCT meta-analysis. Diagnostics (Basel). 2024;14(14):1522.
    PubMed: 39061659DOI: 10.3390/diagnostics14141522· Meta-analysis of LC-OCT across 904 lesions: pooled sensitivity 86.9% and specificity 91.1% (AUC 0.914) for malignant skin tumors.
  10. [10]
    Manfredini M, Bigliardi L, Gabbiadini A, et al. RCM-guided spaghetti for facial LM: 6-year follow-up. Dermatol Surg. 2024.
    DOI: 10.1097/DSS.0000000000004508· RCM-guided spaghetti excision matched WLE recurrence rate (5.7%) with less than half the margin width (2.7 mm vs 6.7 mm) at 6 years.