Subs ecialty Clinics: Dermatology Cutaneous Micrographic Surgery: Mohs Procedure
PAMELA K. MILLER, M.D., * RANDALL K. ROENIGK, M.D., DAVIn G. BRODLAND, M.D., HENRY W. RANDLE, M.D.,t Department of Dermatology
Skin cancer is an increasingly serious public health issue that affects a high percentage of the population. Surgical resection is still standard treatment for skin cancer, but for difficult cases, cutaneous micrographic surgery, originally described by Mohs, is our preferred technique because of the routine methodic accuracy for evaluation of the surgical margin, the high rate of oncologic cure, and the tissue-sparing quality of the procedure. We report the Mayo Clinic experience with cutaneous micrographic surgery from July 29, 1986, through June 30, 1991, which consisted of 3,355 cases (principally basal cell and squamous cell carcinoma). Herein we discuss practical concerns about this procedure: duration of the technique, reconstruction, cure rates, tumors best treated by cutaneous micrographic surgery, and cost. In addition, we review the Mayo Clinic multidisciplinary management of difficult skin cancers.
Skin cancer is the most common type of cancer in humans; more than 600,000 new cases are treated annually in the United States. I Most basal cell (BCC) and squamous cell carcinomas (SCC) are managed successfully by surgical excision.>' electrodesiccation and curettage.v' cryosurgery,"? and, occasionally, irradiation.I''!' For high-risk recurrent tumors (for example, ones that have been treated previously, are histologically aggressive, or are located in high-risk sites), cutaneous micrographic surgery (MS), originally de" scribed by Mohs, is the procedure of choice. This technique offers the highest cure rates, while maximizing the preservation of normal tissue to simplify reconstruction of the defeet.":" The historical background and method of performing MS have been reviewed in detail elsewhere.14.18-22 The purpose of this article is to report the Mayo Clinic experience
with MS. Cost comparison and practical concerns are also discussed, as is the Mayo Clinic multidisciplinary management of difficult skin cancers.
it 'tEVIEW OF PRACTICE We reviewed the surgical records of all patients who underwent MS and fresh-frozen tissue analysis, originally described by Mohs, 126.96.36.199 at the Mayo Clinic between July 29, 1986, and June 30, 1991. All diagnoses were confirmed by examination of biopsy specimens of skin and reviewed by a dermatopathologist. Patients.-During the study period, 2,265 patients (1,245 men and 1,020 women) with 3,355 skin tumors underwent MS. The ages of the patients ranged from 22 to 101 years (Table 1). Most patients (2,049 [90.5%]) were 60 years of age or older. In comparison, a total of 7,566 BCCs and 3,355 SCCs were managed by all surgical methods during the same period at the Mayo Clinic. Therefore, of 10,921 BCCs and *Current address: Pariser Dermatology Specialists, Ltd., Norfolk, SCCs, 30.7% were treated by MS. Virginia. Tumors Treated.- The 3,355 skin tumors treated by MS tMayo Clinic Jacksonville, Jacksonville, Florida. included BCCs, SCCs, Merkel cell carcinomas, Address reprint requests to Dr. R. K. Roenigk, Department of dermatofibrosarcoma protuberans, and other tumors (Table 2). Most were BCCs, followed by SCCs. Dermatology, Mayo Clinic, Rochester, MN 55905. Mayo Clin Proc 67:971-980, 1992
Mayo Clin Proc, October 1992, Vol 67
Table l.-Age* of Patients Who Underwent Cutaneous Micrographic Surgery at the Mayo Clinic Between July 29, 1986, and June 30, 1991
Table 2.-Skin Tumors Treated by Cutaneous Micrographic Surgery at the Mayo Clinic Between July 29, 1986, and June 30, 1991
No. of patients
50-59 60-69 70-79 80-89 ~90
16 136 197 411
376 424 47
*At time of initial assessment.
Size of Tumors.-Of all the treated tumors for which a size was recorded, 8.5% (271) were 1 em or smaller in diameter (Table 3). The number of lesions between 1.0 and 1.9 em in diameter (1,443 [45.2%]) was almost equivalent to those that were 2 em or larger in diameter (1,478 [46.3%]). In our series, the largest lesion was a 20.5-cm by 15.3-cm BCC that involved the cheek, temple, left ear, and scalp. Stages of Excision.-After two specimens (layers or stages) of tissue were excised, 87.4% of tumors had histologically clear margins (Table 4). Only 32 patients required five or more stages of excision; one patient required eight stages. Site of Tumor.-Of all the tumors treated, 96.6% (3,241) were located on the head or neck (Table 5). Most lesions on the arms, hands, and feet were SCCs. Reconstruction.-Approximately a third of the wounds (1,137 [33.9%]) were allowed to heal by second intention (Table 6). Of the remaining defects, 1,914 (57.0%) were repaired in the Department of Dermatology, and 304 (9.1%) were referred to other surgical specialists for repair. Types of closure performed in the Department of Dermatology included primary closure, local flap, and skin graft. Basal Cell Carcinoma.-In our series, 1,842 patients underwent MS for 2,614 BCCs or 34.5% of all BCCs treated at the Mayo Clinic during the study period (Table 2). The ratio of men to women was 1.06:1. Ofthe 2,614 BCCs, 588 (22.5%) recurred after previous therapy, usually surgical. Among patients with BCC, the men ranged in age from 25 to 95 years old and the women from 22 to 101 years old. As in the overall group, most patients with BCC were 60 years of age or older (81.4% of men and 91.2% of women). The largest number of men were 70 to 79 years old (347), and the largest number of women were 80 to 89 years old (347). Almost half of the BCCs (47.1%) in our series were 2 em or larger in diameter (Table 3). The lesions that were 1 em or smaller were located on the eyelids and nose, areas where tissue sparing is important.
Type of tumor Basal cell carcinoma Squamous cell carcinoma Otherst
Tumors No. %
2,614 711 30
77.9 21.2 0.9
No. recurrent after previous therapy (not MS)* 588
*MS =cutaneous micrographic surgery. t Atypical fibroxanthoma, basaloid hamartoma, dermatofibrosarcoma protuberans, desmoplastic trichoepithelioma, eccrine adenocarcinoma, keratoacanthoma, lentigo maligna melanoma, malignant hidradenoma, Merkel cell carcinoma, microcystic adnexal carcinoma, sebaceous carcinoma, sebaceous epithelioma, sweat gland carcinoma, trichoadenoma, trichoepithelioma, verrucous carcinoma.
Histologically tumor-free margins were obtained for 85.7% of BCCs after one ortwo specimens (layers or stages) of tissue were removed (Table 4). Almost half of the tumors (48.9%) had clear margins after one stage of excision. Squamous Cell Carcinoma.-Of the 3,355 tumors treated by MS, 711 (21.2%) were SCCs (Table 2). Coincidentally, these 711 SCCs also represent 21.2% of all cutaneous SCCs treated at the Mayo Clinic during the study period. These cancers occurred in 531 patients (328 men [61.8%] and 203 women [38.2%]), and 90 (12.7%) were recurrent lesions after previous surgical treatment. Most patients with SCC (71.2%) were 70 years of age or older. The largest group of patients (36.5%) was between 80 and 89 years old. Of the SCCs for which data were available, more than half (376 [55.4%]) were 1.9 em or smaller in diameter (Table 3), and 635 of the tumors (93.5%) had histologically tumorfree margins after two or fewer specimens (layers or stages) of tissue were removed (Table 4). Other Tumors.- Tumors other than BCC and SCC that were treated during our study are listed in Table 2. Unusual cutaneous tumors that have contiguous growth patterns are considered for management with MS. Cure Rates and Recurrences After MS.-The 1- to 6year follow-up is too short to compare the cure-rate statistics of our series of patients with those of series published in the literature, in which 5-year follow-up is standard. To date, our group has an overall cure rate of 99.01 %; however, this figure is likely to decrease slightly. By type of tumor, the cure rate was 99.12% and 98.59% for BCC and SCC, respectively. Of the 3,355 tumors treated in our study, only 33 recurred after MS. In the group of 33 skin tumors that recurred after MS, 70% were BCC (of these, 74% were morpheaform) and 30%
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Table 3.-Sizes of Tumors Treated by Cutaneous Micrographic Surgery at the Mayo Clinic Between July 29, 1986, and June 30, 1991* Size
All tumor types
Basal cell carcinoma
Squamous cell carcinoma