Dermoscopy Holds Limited Potential to Differentiate BCC From Benign Tumors

A new study examined the potential of using dermoscopy to distinguish basal cell carcinoma (BCC) from benign skin tumors and found that despite some differences in the frequency of dermoscopic features between the conditions, dermoscopy alone is not sufficient for a reliable diagnosis.

The article, published in Cancers, noted that although most cases of BCC can be diagnosed based on clinical and dermoscopic assessment, some presentations can overlap with benign adnexal skin tumors such as trichoblastic tumors (TT). The study authors noted that histopathological assessment is currently the gold standard for a differential diagnosis of TT and BCC, but they aimed to investigate whether dermoscopy could be used in clinical practice instead. Dermoscopy, a noninvasive technique using a handheld dermatoscope, is less time-consuming than excising and performing a histopathological assessment on a potential tumor.

Using medical records from the dermatology department at the Medical University of Gdańsk in Poland, the authors analyzed 502 cases of BCC and 61 cases of TT that were excised and histopathologically examined between May 2016 and August 2021. Two investigators who were blinded to the histopathological diagnosis graded clinical and dermoscopic pictures of the tumors according to predefined criteria. The clinical data included patient age and gender, as well as tumor location, size, visible pigmentation and ulceration, and lesion morphology.

Patients with BCC tended to be older than those with TT (mean age, 71.4 vs 64.4 years, respectively; P = .0152), and women made up a higher proportion of the BCC group, although the difference was not statistically significant (52.0% vs 44.3%; P = .279). The BCC group had larger tumor size than the TT group (mean, 11.0 vs 8.2 mm; P = .001) and more often featured clinically visible ulceration (59.4% vs 19.7%; P < .001).

The analysis of dermoscopic variables revealed some characteristics associated with the different diagnoses: Dermoscopically visible ulceration was more common in the BCC group than the TT group (52.2% vs 14.8%; P < .0001) whereas pigmented structures (brown dots and brown globules), cloudy/starry milia-like cysts, and yellow globules were less common in the BCC group (all P < .05).

The study authors also created a binary classification algorithm that was tested and validated on the samples to distinguish BCC from benign tumors. It achieved an area under the curve of 79.23% (95% CI, 69.69%-88.76%), which the authors deemed insufficient for use in clinical practice, as very high sensitivity is needed when diagnosing malignant vs benign tumors given the serious consequences of false negatives.

The literature contains mixed evidence on the epidemiological and dermoscopic characteristics of TT, the authors noted, and their results contrast with some prior studies that had revealed differences in clinically observable pigmentation between BCC and TT cases.

The current study’s limitations included its retrospective and single-center design, as well as that the included patients had lighter skin phototypes.

The authors concluded that “despite differences in frequency of clinical and dermoscopic features between BCC and TT in the studied group, differential diagnosis based on these variables is not reliable based on the developed algorithm, as the overlap of the analyzed features was observed in both tumor types.” They recommended that histopathological examination remain the gold standard for diagnostic use in distinguishing BCC from TT.

Reference

Sławińska M, Płaszczyńska A, LakomyJ, et al. Significance of dermoscopy in association with clinical features in differentiation of basal cell carcinoma and benign trichoblastic tumours. Cancers (Basel). Published online August 17, 2022. doi:10.3390/cancers14163964