A Study of Microscopic Interpretation of Feozen Sections in Mohs Micrographic Surgery for Basal Cell Carcinoma

Jung, Sung Moon; Lee, Min Soo; Kim, Ki Ho; Huh, Ki Young; Hong, Sook Hee; Joe, Gwang Yeol

Abstract

BACKGROUND: Mohs micrographic surgery (MMS) achieves higher cure rates for cutaneous squamous cell and basal cell carcinomas than any other therapeutic modality. For a unifocal tumor, a 100% cure rate after MMS should theoretically be possible, however for primary basal cell carcinoma, 98-99% 5-year disease-free rates have been achieved.
OBJECTIVE
Our purpose was to investigate the pitfalls in microscopic Interpretation of frozen sections in Mohs micrographic surgery for basal cell carcinoma which decrease the cure rate after surgery.
METHODS
From March 1991 to February 1998, fifty-nine patients were diagnosed with basal cell carcinoma at our department. All the tumors were removed with Mohs micrographic surgery and frozen section specimens were stained with hematoxylin-eosin. The microscopic evaluation was done by Mohs surgeon and pathologist.
RESULTS
We can summarize the matters that demand special attention during microscopic Interpretation of frozen sections in Mohs surgery as two groups. First, as false negative interpretation, there are 1) small nests of tumor scattered within areas of heavy inflammation 2) tumor present along the hair follicle, 3) tumor present along a cut edge, 4) empty space in a tissue section, 5) hair follicle-like structure of the tumor, 6) gland-like structure of the tumor, and 7) infiltrative BCC-like inflammatory cells. Second, as a false positive interpretation, there are 1) foreign body reactions or scar containing trapped pilosebaceous structures, 2) horizontal and tangential cuts through the pilosebaceous apparatus, 3) some epidermal neoplasms including solar lentigines, seborrheic keratoses, and acantholytic actinic keratoses, and 4) contamination of the tumor tissue.
CONCLUSION
With careful attention to the examples which can affect the interpretation as mentioned above, it may be possible to detect complete removal of tumor mass and achieve higher cure rate. We could achieve a 100% of cure rate for primary basal cell carcinoma and 95 % of cure rate for recurrent basal cell carcinoma after Mohs Micrographic surgery in our hospital from March 1991 to February 1998.