Mixed results seen for imaging skin tumors before Mohs surgery



SAN DIEGO – Dermoscopy was no better than visual clinical inspection for delineating skin tumor margins before Mohs micrographic surgery, based on data from a pooled analysis, according to Dr. Syril Que.

But her review showed that confocal microscopy and optical coherence tomography devices “may be of potential diagnostic value – both for defining BCC [basal cell carcinoma] tumor margins prior to excision and for minimizing the number of stages needed subsequently,” said Dr. Que, a dermatology resident at the University of Connecticut Health Center in Farmington. “Nevertheless, there are limitations to both imaging modalities, and adjustments that need to be made before they are incorporated as a standard of practice in Mohs surgery,” she emphasized.

In a search of PubMed, Dr. Que found 27 original research studies that compared noninvasive imaging devices for delineating skin tumor margins with Mohs histology results. The studies were published between 2004 and 2014; 26 studies included BCC specimens, 3 included squamous cell carcinomas, and only 1 looked at lentigo maligna and melanoma. When broken down by type of imaging device, 17 of the studies focused on confocal microscopy, 5 were of dermoscopy, and 5 were of optical coherence tomography, she added. The number of specimens per study ranged from 2 to 115.

Only one study found an added diagnostic benefit from dermoscopy of skin tumor margins, compared with visual inspection, and that was a report of only two cases, said Dr. Que. The larger studies of 40-60 patients showed no significant difference between clinical inspection and dermoscopy for delineating margins. “Currently available evidence shows that dermoscopy has no advantage over clinical inspection when used prior to Mohs surgery,” she concluded.

Studies of confocal microscopy of BCCs were more promising, Dr. Que noted. These papers reported sensitivities of 73%-100%, and specificities of 89%-99%. “Sensitivity and specificity tended to be lower for micronodular or infiltrative BCCs,” she added. The papers did not report sensitivity or specificity values for squamous cell carcinomas, but did state that it was difficult to use confocal microscopy alone to distinguish between these tumors and actinic keratoses, she said at the annual meeting of the American Society for Dermatologic Surgery. Few studies addressed the use of confocal microscopy for melanoma or lentigo maligna, she added.

Finally, the papers on optical coherence tomography reported that the device “showed excellent correlation with histopathology, and was 84% accurate in predicting surgical margins,” said Dr. Que. “Optical coherence tomography appropriately assessed the subclinical spread of tumor, based on the close proximity of optical coherence tomography margins to the final Mohs defect,” she added.

Dr. Que said she had no relevant financial disclosures.

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