Mohs micrographic surgery is indicated for tumors that occur in high-risk
areas
Tumors located around the eyes, ears, nose, and lips have higher recurrence
rates than do those in other parts of the body because they occur within
embryonic fusion planes. This results in tumors invading more deeply
and aggressively than would otherwise be expected.
Other indications for Mohs surgery are recurrent tumors, tumors greater
than 2 cm in diameter, and incompletely excised carcinomas. Tumors that
do not meet these criteria but are indications for Mohs surgery regardless
of their location include cutaneous malignancies with ill-defined tumor
borders and with aggressive histology. Morpheaform and metatypical basal
cell carcinomas also should be treated with the Mohs technique to trace
out all extensions of tumor. It is not uncommon to encounter perineural
spread
of tumor, which can track much farther than anticipated from the center
of the tumor mass. This can result in tumor invasion into bone or brain.
