Non-Invasive Diagnosis of a Facial Tumor Using Dermoscopy and Successful Treatment with 595 nm Pulsed Dye Laser

Clear cell acanthoma (CCA) usually appears as a shiny, red-colored papule or nodule, ranging in size from 3 to 20 mm. It may be covered with a thin crust and surrounded by a collarette of ‘wafer-like’ scales. Invasive removal have been preferred such as excision, curettage, electrofulguration, cryotherapy, and CO₂ laser ablation1.

When such dermatosis occurs on the face, the patient is likely to be apprehensive about the invasive procedures, like biopsy or an operative removal, which may result in irreversible scarring. Therefore, non-invasive methods for both the diagnostic and treatment processes are especially valuable in such cases. In this report, we describe a patient with CCA who was presumptively diagnosed and treated using the non-invasive modalities of dermoscopy and pulsed dye laser (PDL), respectively.

A 40-year-old Asian male presented at our clinic with a slowly growing nodule on the left side of his face. The nodule was well-demarcated, 5-mm sized in diameter, shiny erythematous-to-brown colored, and flattened with minimal scaling (Fig. 1A). Since he refused to undergo a biopsy for cosmetic concern, dermoscopy was applied for detailed examination. On applying slight pressure during the dermoscopic examination, the background blanched to a pinkish-color, and its prominent vascular puncta were defined more clearly, revealing fine red dots with a reticular arrangement (‘pearl necklace’ or ‘string of pearls’ pattern) (Fig. 1B). Based on these findings, the lesion was presumptively identified as a CCA.

Fig. 1
(A) Clinical photograph of the lesion during initial visit. (B) Dermoscopic image of the lesion showing the typical ‘string of pearls’ vascular pattern, indicating a diagnosis of clear cell acanthoma.

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Considering the patient's concerns about iatrogenic scarring, 595-nm wavelength PDL (Vbeam perfecta®; Syneron Inc., San Francisco, CA, USA) was chosen as a treatment modality. The parameters were suitably modulated from initial setting (13 J/cm² energy, 20 ms duration), until a mild purpuric response was observed (10 J/cm² energy, 3 ms duration) (Fig. 2A). The bright-red colored vascular puncta turned violaceous following PDL therapy (Fig. 2B).

Fig. 2
(A) Clinical photograph taken immediately following the pulsed dye laser treatment. (B) Dermoscopic image showing purpuric changes in vascular puncta of the clear cell acanthoma lesion.

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The lesion regressed markedly, and the patient was satisfied with the cosmetic outcome. There was no evidence of recurrence during routine follow-up at 8 and at 26 months after treatment (Fig. 3).

Fig. 3
Clinical photograph on routine follow-up. At 8 months (A) and at 26 months (B) after pulsed dye laser treatment.

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The characteristic dermoscopic findings of CCA include red dots, globules, and glomeruloid vessels arranged in a linear or serpiginous manner. In fully developed lesions, these vessels coalesce to form a symmetrical reticular pattern resembling a ‘pearl necklace’2 or a ‘string of pearls’3. The “string of pearls” appearance differs from the appearance of psoriasis wherein vessels are homogeneously and regularly distributed and are not in a line4. Although this pattern is highly specific to CCA, it has also been reported in non-CCA lesions, including lichen-planus-like keratosis (LPLK) and seborrheic keratosis4, 5. Although biopsy is considered the gold standard method for diagnosing skin lesions, it is invasive and can result in a permanent scar. Hence, confirmatory biopsy might be avoided in patients who are young or for those who have concerns about permanent scarring, especially in the facial area. Our patient refused all invasive procedures and sought a non-surgical approach for both diagnosis and treatment. Dermatologists should thus provide alternative non-invasive methods for diagnosis and treatment of skin lesions. In this regard, dermoscopy can be a useful supplemental tool6, 7. Given that the lesion was a solitary, erythematous, and brown shiny papule, clinical examination favored a diagnosis of CCA. Moreover, considering the patient's young age, we could rule out other diseases with dermoscopic features similar to CCA, such as LPLK and seborrheic keratosis. Hence, we presumptively diagnosed the lesion as CCA. Moreover, the detection of the dilated blood vessels through a dermoscope indicates that it is possible for the external laser beam to reach the enhanced superficial microvasculature. The favorable clinical efficacy of PDL for CCA substantiates the findings of a previous clinical study that demonstrated the efficacy of PDL for psoriasis8. It was based on the evidence that microvascular changes occur before T-cell infiltration and epidermal hyperplasia in psoriatic plaque formation9, 10, 11. Like psoriasis, CCA have been suggested as a localized form of psoriasiform dermatitis1 due to its histopathologic similarity3 with same cytokeratin expression profile to psoriatic plaques12, 13. Therefore, we could surmise that a selective destruction of the dilated dermal microvasculature led to the regression of the CCA lesion.

A limitation of this study is that we did not describe both patterns, i.e., patterns obtained with and without the application of pressure. When pressure is applied during dermoscopic examination, the vascular structures may disappear14. Therefore, dermoscopy should be performed carefully to avoid the loss of the vessel structures; the use of ultrasound gel for immersion will be encouraged in the future.

In the present case, dermoscopy was a useful tool for diagnosing CCA in a non-invasive manner, while providing information for the selection of the non-invasive modality. Moreover, the successful treatment of lesions presumptively diagnosed as CCA using PDL could be utilized in other such cases to achieve optimal aesthetic outcomes. To our knowledge, this is the first report describing a patient with presumed CCA who was successfully treated with PDL. We share our experience with the expectation that the present case may provide dermatologists with fresh insights into the practical applications of various non-invasive techniques.