Summary Background Frozen histological sections are used for intraoperative margin assessment during Mohs surgery. Fluorescence confocal microscopy (FCM) is a new tool that offers a promising and faster alternative to frozen histology. Objectives To evaluate prospectively in a clinical setting the accuracy of FCM vs. frozen sections in margin assessment of basal cell carcinoma (BCC). Methods Patients with BCC scheduled for Mohs surgery were prospectively enrolled. Freshly excised surgical specimens were examined by FCM and then frozen sections were evaluated. Permanent sections were obtained, in order to validate the sample technique. A blind re‐evaluation was also performed for discordant cases. Sensitivity and specificity levels, as well as positive and negative predictive values (PPV and NPV, respectively), were calculated and receiver–operating characteristic curves generated. Results We enrolled 127 BCCs in as many patients (40·2% females). Seven hundred and fifty‐three sections were examined. All BCCs were located in the head and neck area. In evaluating the performance of FCM vs. frozen sections, sensitivity was 79·8%, specificity was 95·8%, PPV was 80·5% and NPV was 95·7% [area under the curve 0·88, 95% confidence interval 0·84–0·92 (P < 0·001)]. Forty‐nine discordant cases were re‐evaluated; 24 were false positive and 25 false negative. The performance of FCM and frozen sections was also evaluated according to the final histopathological assessment. Conclusions We found high levels of accuracy for FCM vs. frozen section evaluation in intraoperative BCC margin assessment during Mohs surgery. Some technical issues prevent the wide use of this technique, but new devices promise to overcome these limitations.

The use of confocal microscopy is possible using two different modalities: first, at patient's bedside for a rapid in vivo diagnosis of basal cell carcinoma and second, in the operating room directly on freshly excised specimen for a fast ex vivo margin-controlled surgery. In the current review, we report the main application of confocal microscopy for basal cell carcinoma diagnosis and management in both modalities.

The clinical and dermoscopic features of the vast majority of uncommon variants of cutaneous melanoma have been rarely reported, leading to difficulty in making accurate diagnoses.OBJECTIVE To define the main clinical and dermoscopic features of the most frequently reported but uncommon histologic variants of cutaneous melanoma.EVIDENCE REVIEW A 2-step systematic review of the literature was performed (from inception to November 2018) using PubMed, Embase, and Cochrane Central Register of Controlled Trials databases. The first step identified those uncommon variants of melanoma for which at least 1 case reporting dermoscopy was described in the literature. The keywords searched were melanoma, uncommon, rare, dermoscopy, and dermatoscopy. In the second step, each previously identified uncommon variant was searched for in the same databases by combining the following terms with melanoma, dermoscopy, and dermatoscopy: amelanotic, hypopigmented, animal, melanocytoma, balloon, desmoplastic, follicular, nested, nevoid, dermal, spitz*, spindle, and verrucous. The institution's database was also searched from January 2012 to September 2019 for histopathologically confirmed cases of the same melanoma variants. Each reviewer also assessed the quality of reporting in the included articles based on previously described guidelines.FINDINGS In total, 62 articles met the inclusion criteria, reporting 433 melanoma cases. An additional 56 cases of uncommon melanoma variants were retrieved from the institution's database for a total of 489 cases: 283 cases of amelanotic superficial spreading melanoma, 18 cases of animal-type and pigmented epithelioid melanocytoma, 7 cases of balloon cell melanoma, 71 cases of desmoplastic melanoma, 3 cases of follicular melanoma, 10 cases of nested melanoma, 33 cases of nevoid melanoma, 2 cases of primary dermal melanoma, 57 cases of spitzoid melanoma, and 5 cases of verrucous melanoma. These variants of melanoma occurred more frequently in women than men (147 cases vs 132 cases). Clinically, these tumors were mainly palpable (162 of 217 [74.7%]) or amelanotic (283 of 489 [57.9%]) lesions that could resemble other benign or malignant skin conditions; dermoscopy typically revealed a homogeneous pinkish background, white structures, and polymorphic vessels. The mean age of all included was 58 years (range, 1-89 years).CONCLUSIONS AND RELEVANCE Uncommon melanoma variants may resemble both inflammatory disorders and other cutaneous neoplasms, representing a diagnostic pitfall even for the most experienced dermatologist. The purpose of this systematic review was to provide an extensive and detailed overview of specific clinical and dermoscopic features of each uncommon melanoma variant, highlighting the main criteria for differentiating these variants from other benign or malignant skin lesions.