Intraoperative Consultations During Skin Surgery

Introduction

Frozen section is rarely used for primary diagnosis in dermatopathology but is often requested for management of skin cancer. The principal treatment for most skin malignancies consists of primary excision with negative margins. The operative procedure may include use of flaps or grafts following margin clearance, depending on the size of the defect needed to clear margins. Accordingly, a false positive result may potentially lead to a larger excision that requires a more complex procedure; and a false negative result may leave tumor present underlying a flap or graft, often in a cosmetically sensitive location. Application of frozen section in skin excisions may be used for margin evaluation either in a conventional fashion or as part of Mohs micrographic surgery, the latter of which is beyond the scope of this chapter. Traditional frozen section examination of margins in dermatopathology is most commonly applied to epithelial neoplasms, typically for basal cell carcinoma and less commonly for squamous cell carcinoma excisions. Adnexal carcinomas are rarely encountered. Frozen section in diagnosis and management of melanocytic lesions is controversial and usually not indicated ( Table 5-1 ).

Indications and Contraindications for Frozen Sections

Margin assessment, most commonly for basal cell and squamous cell carcinomas, is routinely requested. Depth of invasion in large squamous cell and basal cell carcinomas is an uncommon request. Staging of such carcinomas is recommended for all tumors greater than 2 cm, and although depth of invasion may change the pathologic stage, it does not in our experience alter intraoperative management. Furthermore, it cannot be reliably measured on frozen section.

Any skin excision may be subject to a request for frozen section; however, in some instances it is contraindicated and should not be performed ( Table 5-2 ). Primary diagnosis of a small (1.5 cm or less) skin lesion is of limited value in most situations and frequently leads to limited or incomplete diagnosis and a lack of sufficient lesional tissue on which to make a definitive diagnosis on permanent sections. This includes both common basal cell and squamous cell carcinomas, other less common cutaneous adnexal and Merkel cell carcinomas, and mesenchymal lesions of the skin, such as dermatofibromas, and superficial soft tissue tumors, such as dermatofibrosarcoma protuberans.

Primary diagnosis of cutaneous melanocytic lesions is the subject of considerable debate in the literature. Except in the very unusual scenario of large, bulky tumors at presentation, we regard frozen section diagnosis for primary diagnosis of melanocytic lesions as contraindicated, having a detrimental effect on the pathologist’s ability to render a final diagnosis and/or to assess margin status, staging and prognostic factors. Although margin assessment may be requested for melanocytic lesions, we regard this practice as controversial and potentially harmful for clinical practice, and we do not routinely perform it.

As with all body sites, sampling of tumor deposits in the skin may be requested for tumor banking and ancillary studies, with confirmation by intraoperative pathology examination requested. This is more likely to be requested in the setting of cutaneous metastases from other sites.

Rarely are debridement specimens for infectious processes subjected to requests for intraoperative consultation. However, the case can be made for frozen section in order to triage tissue for microbiologic cultures and other assays to test for specific microorganisms.

An infrequent but important indication for intraoperative examination is to confirm the presence of toxic epidermal necrolysis or distinguish it from staphylococcal skin syndrome. This indication should be considered a true “dermatopathologic emergency” requiring after-hours intraoperative evaluation if requested.

Rarely, cutaneous lymphomas or lymphoproliferative disorders secondarily involving the skin may be subjected to frozen section requests. Though we discourage this practice, a legitimate case can be made for the purpose of establishing the presence of diagnostic tissue and triaging tissue for flow cytometry and/or molecular studies.