Histopathologic examination of basal cell epitheliomas reveals collections of cells with dark-staining nuclei and scant cytoplasm. The periphery of the cell masses shows cells in a palisade arrangement resembling the basal layer of the epidermis. Treatment of basal cell epitheliomas consists of complete surgical excision, destruction by curettage and electrodesiccation, or radiation therapy. Cryosurgery has been employed for selected lesions, especially superficial basal cell carcinomas. A margin of seemingly normal tissue should be removed around the tumor to prevent recurrence arising from invasion by strands of tumor cells. The clean margins must be monitored by histopathologic examination.
Recurrent basal cell carcinomas are usually difficult to cure, but Mohs’ microscopic controlled surgery, when it is performed by a specially trained physician, is effective in eradicating the entire tumor. Routine in vivo chemosurgical fixation of the tumor with zinc
chloride paste is no longer required. In the current procedure, fresh tissue is removed after local anesthesia, and frozen sections are examined microscopically. This more efficient method spares a larger amount of normal skin and reduces the discomfort associated with chemical fixation. The tumor is removed layer by layer, and all margins are carefully examined until a tumor-free plane is achieved.
Indications for microscopic controlled excision of skin cancer include recurrent basal cell epitheliomas and squamous cell carcinomas; tumors with indistinct margins, such as sclerosing basal cell epitheliomas; and lesions in such areas as the inner and outer canthus of the eye and the tip of the nose, where maximal preservation of normal skin is desirable. For certain complicated or advanced tumors, the fixed-tissue approach is considered more reliable than the fresh-tissue technique.