Line‐field confocal optical coherence tomography for actinic cheilitis: A descriptive study

Dear Editors,

Actinic cheilitis (AC), also referred to as farmer's lip or sailor's lip, is characterized by confluent actinic keratoses (AK) affecting the lips, most commonly the lower lip. Similar to isolated AK, AC is a premalignant condition resulting from chronic cumulative exposure to ultraviolet (UV) radiation. It predominantly affects older individuals, males, and those with fair skin phototypes. ¹

Clinically, AC is characterized by dryness, scaling, atrophy, indistinct vermilion borders, and erosions ² (Figure 1a). Importantly, squamous cell carcinoma (SCC) arises in approximately 10% to 30% of cases, highlighting the malignant potential of this condition and the need for early recognition and management. ²

FIGURE 1.

(a) Clinical image of actinic cheilitis of the lower lip showing dryness, scaling, atrophy, indistinct vermilion borders, and erosions. (b) Dermoscopy (× 10) revealing scales, white radial lines arranged perpendicularly on a white‐red background, and diffuse dotted and irregular linear vessels. (c) Histological section (hematoxylin‐eosin stain, original magnification × 10) of actinic cheilitis of the lower lip showing epidermal hyperkeratosis (green arrows), acanthosis (yellow bracket), vascular ectasia (red ribbon), dermal elastosis (light blue circle), and pleomorphic keratinocyte nuclei.

Histopathologic examination remains the gold standard for the diagnosis of AC. While the clinical features may strongly suggest the diagnosis, and dermoscopy can provide supportive findings (Figure 1b), a biopsy is essential to confirm the presence and extent of epithelial dysplasia and to rule out early invasive SCC. ³ Histologically, AC is characterized by a variable degree of keratinocyte atypia, ranging from basal layer dysplasia to full‐thickness epithelial involvement (Figure 1c). Additional features include hyperkeratosis, parakeratosis, acanthosis or epidermal atrophy, and loss of normal epithelial maturation. The underlying dermis typically shows marked solar elastosis and a chronic inflammatory infiltrate composed predominantly of lymphocytes. ⁴ Recent classifications, such as the Röwert‐Huber system, emphasize not only the degree and distribution of intraepidermal atypical keratinocytes, but also the assessment of basal proliferation, as quantified by the so‐called PRO score, as relevant histopathological features in AC. ⁵

Line‐field confocal optical coherence tomography (LC‐OCT) is a non‐invasive imaging technique used in dermatology that combines high‐resolution vertical sectioning similar to histological sections, horizontally‐oriented perspective similar to reflectance confocal microscopy (RCM), and innovative three‐dimensional (3D) reconstruction of cutaneous structures up to a depth of approximately 500 µm. ⁶ This multimodal capability positions LC‐OCT as a promising diagnostic tool for both melanocytic and non‐melanocytic malignant neoplasms, as well as inflammatory skin diseases. ⁷ , ⁸ , ⁹ A total of eight patients clinically and/or histological diagnosed with AC were evaluated using LC‐OCT (DeepLive^TM LC‐OCT, DAMAE Medical, Paris, France) to assess in vivo morphological features. LC‐OCT criteria for AC were defined and assessed for their presence across all lesions included in the study.

LC‐OCT provides images closely resembling histological sections, allowing the visualization of hyperkeratosis and acanthosis of a dysplastic epithelium, characterized by high density of keratinocyte nuclei with marked pleomorphism, ectatic blood vessels, and the presence of bright, hyperreflective inflammatory cells (Figure 2).

FIGURE 2.

(a) Vertical section of line‐field confocal optical coherence tomography (LC‐OCT) showing epidermal hyperkeratosis (green arrows), acanthosis (yellow bracket), vascular ectasia (red ribbon), and hyporeflective keratinocyte nuclei with pleomorphic morphology. The dermoepidermal junction appears well demarcated, with hyporeflective areas in the dermis corresponding to elastosis (light blue circle). (b) Horizontal section showing multiple bright monomorphic cells at the dermoepidermal junction, consistent with inflammatory infiltrate, as well as scattered disorganized collagen fibers surrounding blood vessels (red ribbon), reflecting underlying fibrosis (yellow cross).

The dermoepidermal junction (DEJ) appears preserved, ruling out stromal invasion diagnostic of SCC. The dermis shows thickened, disorganized collagen fibers, reflecting the fibrosis and elastosis typically observed in AC.

Our study describes the LC‐OCT features of AC and demonstrates that LC‐OCT can reliably identify key morphological characteristics associated with this premalignant condition. Differentiation from normal lip mucosa appears feasible (Figure 3), as features such as hyperkeratosis, acanthosis, nuclear crowding, nuclear atypia, and dilated vessels were consistently observed in AC lesions.

FIGURE 3.

Vertical section of line‐field confocal optical coherence tomography (LC‐OCT) showing the microstructure of healthy lip tissue. The stratum corneum (green arrow) shows physiological thickness, keratinocytes exhibit homogeneous and monomorphic nuclei, and no acanthosis is observed. The dermoepidermal junction (dashed orange line) is flat and clearly visualized, blood vessels (red ribbon) retain a preserved hook‐like structure, and the dermis appears homogeneous with orderly arranged collagen fibers.

The use of LC‐OCT may be limited in lesions with marked hyperkeratosis, as the thickness of the stratum corneum can impair image quality due to the intrinsic depth limitations of the technique. These findings support the utility of LC‐OCT in the non‐invasive evaluation of AC and suggest potential clinical applications, such as treatment monitoring, as well as its emerging role in the diagnosis and monitoring of AK. ¹⁰ Moreover, recent studies have demonstrated that artificial intelligence approaches, specifically convolutional neural networks, can be applied to LC‐OCT imaging for automated quantification of atypia and basal proliferation in actinic keratoses, known as the PRO score. This advancement supports more objective assessment and monitoring of these lesions. ¹¹

In conclusion non‐invasive monitoring using this technique allows for a reduction in the number of biopsies, which is particularly valuable in aesthetically sensitive areas such as the lips. However, in cases where invasive SCC is suspected, biopsy remains mandatory, as does radical treatment. Nevertheless, further studies with larger sample sizes are warranted to validate and define the role of LC‐OCT within the diagnostic algorithm for this condition.

CONFLICT OF INTEREST STATEMENT

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