Introduction: In the dermatologic surgery practice, Mohs micrographic surgery is of great value in the excision of cutaneous neoplasias. Nevertheless, in certain types of neoplasia, immunohistochemistry can increase diagnostic accuracy.
Objective: To describe the use of Mohs micrographic surgery associated to immunohistochemistry and evaluate their effectiveness regarding traditional methods.
Method: Mohs micrographic surgery was performed in 5 cases of diverse cutaneous neoplasias. Tissue evaluation with hematoxylin-eosin and immunohistochemistry were carried out intraoperatively.
Results: There was greater prevalence of elderly female patients with higher frequency of recurred basal cell carcinomas in the face. In all cases it was possible to perform immunohistochemistry in the frozen specimen. In most cases, primary closure was carried out in the first stage of the Mohs surgery, without postoperative complications.
Conclusion: The combination of the two techniques can increase the procedure's sensitivity, guaranteeing the presence of free margins, leading to fewer recurrences and allowing the preservation of a greater amount of neoplasia-free tissue.

Keywords: MOHS SURGERY, IMMUNOHISTOCHEMISTRY, SKIN NEOPLASMS

The Merkel cell carcinoma is a rare tumor of neuroendocrine and epidermal origin and with poor prognosis. It is classically associated with immunosuppression, exposure to the sunlight and, more recently, with the polyomavirus. It is positive for epithelial and neuroendocrine markers. The combined expression of these markers confirms the diagnosis. Polyomavirus tumors have an unfavorable prognosis. The authors report a case of Merkel cell carcinoma with atypical immunophenotype (CK20 negative) and aggressive behavior. The present report is aimed at highlighting the importance of dermatologists having knowledge of different immunophenotypes that may be associated with the Merkel cell carcinoma.

Keywords: CARCINOMA, MERKEL CELL; IMMUNOHISTOCHEMISTRY; MERKEL CELL POLYOMAVIRUS

Patients with giant congenital melanocytic nevus are at higher risk of developing melanoma. After the first diagnosis of melanoma, there is also a higher incidence of subsequent melanomas in the same patient. However, the ideal therapy for this type of nevus is still controversial. We report the case of a patient with giant congenital nevus associated with multiple synchronous melanomas and the proposed treatment.

Keywords: Melanoma; Nevi and melanomas; Neoplasms