Rapid Preparation of High-Quality Frozen Sections Using a Membrane and Vacuum System Embedding Machine

BACKGROUND A wide variety of embedding techniques have been employed to process frozen sections for Mohs micrographic surgery. Prospective data comparing different techniques are lacking.
OBJECTIVE The purpose of this study was to compare tissue processing times and slide quality using the three embedding techniques.
METHODS Seventy-five consecutive Mohs surgery tissue specimens, measuring 1 cm in diameter, were prospectively randomized to processing with the CryoHist, the Cryocup, or the Miami Special. Tissue preparation times were recorded, and slide quality was evaluated. Tissue specimen preparation was standardized to exclude the use of relaxing incisions or other tissue manipulations. In a separate evaluation, slide quality was retrospectively evaluated for 50 large specimens (>2.5 cm) processed with the CryoHist machine.
RESULTS The mean tissue processing time was 11.4 minutes using the CryoHist, 12.9 minutes using the Cryocup, and 12.6 minutes using the Miami Special. Slide quality, using epidermal edge as a primary end point, was superior with the CryoHist compared to the other methods. For large (>2.5 cm) en bloc Mohs specimens processed using the CryoHist, the slide quality was excellent with 92.3% of epidermal edge obtained.
CONCLUSIONS The fully automated CryoHist embedding machine enables high-quality frozen sections to be processed in less time than the Cryocup or the Miami Special. Slide quality is excellent, even for larger specimens.     

Post–Mohs Micrographic Surgical Margin Tissue Evaluation with Permanent Histopathologic Sections

Background. Incomplete resection of nonmelanoma skin cancer is associated with a relatively high rate of recurrent tumors. Mohs micrographic surgery provides microscopic evaluation of tumor margins to ensure complete excision of nonmelanoma skin cancers at high risk of recurrence.
Objective. This purpose of this study is to confirm the histologic accuracy of Mohs excision of facial skin cancers by evaluating an additional layer of tissue with permanent histopathologic sections after Mohs excision.
Methods. Two hundred ninety-six Mohs cases were identified, which, after excision, were sent to a single plastic surgeon for reconstruction. This plastic surgeon routinely takes an additional layer and sends for permanent histopathologic evaluation at the time of reconstruction. A review of the pathology reports and tissue specimens on these patients provides valuable data on tumor margins and the effectiveness of the Mohs technique for tumor excision.
Results. Two excisions of nodular basal cell cancer were determined by the pathologist to have positive tumor involvement on post-Mohs permanent tissue. On additional review, one specimen was interpreted to be more consistent with follicular epithelium, and the second was verified as a focus of nodular basal cell cancer.
Conclusion. These data support the high reliability of Mohs surgery for margin control.     

The 20-Minute Rapid MART-1 Immunostain for Malignant Melanoma Frozen Sections

BACKGROUND Immunohistochemical staining has been used to help detect malignant melanoma on Mohs surgery frozen sections. Previous investigators have developed protocols for reliable MART-1 immunostaining of frozen sections, but these protocols are time-consuming.
OBJECTIVE The objective was to report a rapid 20-minute MART-1 immunostaining protocol for frozen sections.
METHODS The protocol was utilized on 30 melanomas treated with Mohs micrographic surgery.
RESULTS The stain clearly highlighted normal background melanocytes, as well as melanocytic hyperplasia and malignant melanoma.
CONCLUSIONS The 20-minute protocol provides a rapid and reliable method for immunostaining of malignant melanoma. The availability of more rapid immunostaining methods improves efficiency of the Mohs laboratory and significantly reduces patient and physician waiting time.     

Use of Ex Vivo Confocal Scanning Laser Microscopy during Mohs Surgery for Nonmelanoma Skin Cancers

Background. Ex vivo confocal scanning laser microscopy offers rapid optical reflectance imaging of excised tissue without conventional frozen histopathology that can potentially expedite Mohs surgery.
Objective. The objective was to determine the feasibility of using ex vivo confocal scanning laser microscopy during Mohs surgery for detecting residual basal cell carcinoma and squamous cell carcinoma.
Methods. One-hundred fifteen Stage I Mohs surgery excisions (92 basal cell carcinoma, 23 squamous cell carcinoma) were imaged with acetowhitening and confocal scanning laser microscopy and compared to conventional Mohs frozen histologic sections for normal and tumor features.
Results. Large aggregates of residual tumor such as nodular basal cell carcinoma were easily detected by ex vivo confocal scanning laser microscopy, whereas smaller tumor foci were not consistently identified. Confocal morphology of tumor subtypes is described.
Conclusion. Ex vivo confocal scanning laser microscopy can potentially expedite Mohs surgery in rapidly detecting large nodular basal cell carcinomas without conventional frozen histopathology. Further improvements in instrumentation and image quality are necessary to allow broader application and acceptance of this novel technology in Mohs surgery.     

Peritumoral Fibrosis in Basal Cell and Squamous Cell Carcinoma Mimicking Perineural Invasion: Potential Pitfall in Mohs Micrographic Surgery

Background. Perineural invasion (PI) in cutaneous basal cell carcinoma (BCC) and squamous cell carcinoma (SCC) is linked to an aggressive course. We describe a histologic mimic for PI that we termed peritumoral fibrosis (PF).
Objective. To describe the morphologic changes associated with PF and to determine the incidence of PF and PI in Mohs frozen sections of BCC and SCC.
Material and Methods. All cases of BCC and SCC that were treated by Mohs micrographic surgery (MMS) at the Skin and Cancer Center, University of Florida College of Medicine, Gainesville, Florida, and the Center for Dermatology and Skin Surgery, Tampa, Florida, during the period from January 1, 2003, to August 1, 2004, were reviewed for the presence of PI and PF. The latter was defined as the presence of concentric layers of fibrous tissue that either surround and/or were surrounded by tumor formations mimicking perineural or intraneural invasion. Seven hundred six cases of BCC and 264 cases of SCC were surveyed. Eleven cases (10 BCC and 1 SCC) with equivocal areas were destained, and immunohistochemical staining with S-100 protein was performed, proving actual PI in all of these cases. Available original hematoxylin-eosin biopsy slides were correlated with the MMS frozen sections.
Results. PF was noticed in 4.5% of SCCs and 5.8% of BCCs. The incidence of unequivocal PI was noted to be 2.6% in SCC and 2.1% in BCC.
Conclusion. We describe a specific pattern of fibrosis noted in BCC and SCC that we called PF. It shows concentric layers of fibrous tissue surrounding and/or surrounded by tumor formations and resembles carcinomatous perineural and/or intraneural invasion. Moreover, PF was found to be a sensitive marker for PI. Mohs micrographic surgeons should be aware of this phenomenon to avoid triggering unnecessary steps in managing these cases, such as irradiation.     

Predictable Tissue Shrinkage During Frozen Section Histopathologic Processing for Mohs Micrographic Surgery

BACKGROUND: When confronted with a histologic specimen that is appreciably smaller than the same tissue specimen immediately after acquisition, the Mohs surgeon is faced with two possibilities, namely that the tissue has either shrunken during laboratory processing or that the histologic specimen is incomplete due to the introduction of technical errors during embedding, cutting, or staining of the skin specimen. Because the entire objective of Mohs micrographic surgery is to precisely examine the entire surgical margin of skin specimens, the surgeon must be able to determine that any size discrepancies introduced during laboratory processing are not related to incomplete surgical specimens. Although there are anecdotal suggestions that skin, like other human tissues, undergoes some degree of shrinkage during routine frozen section processing, the exact nature and magnitude of this phenomenon has not been previously investigated. OBJECTIVE: To quantify the degree of tissue shrinkage in Mohs micrographic surgical specimens processed with routine frozen sections and subsequent hematoxylin and eosin staining. METHODS: A total of 117 Mohs surgery patients (135 cutaneous tumors) were prospectively enrolled. The dimensions of initial stage surgical specimens were determined after removal from the patient, after freezing in a mounting medium, after placement on a glass microscopic slide, and after hematoxylin and eosin staining. Statistical analyses were performed in order to determine the significance of any discrepancies in specimen sizes introduced during laboratory processing. RESULTS: Skin specimens processed by frozen section techniques during Mohs micrographic surgery undergo statistically significant alterations in length. On average the measurements of specimens at the conclusion of histologic processing were 11.6% shorter than the measurements of the same specimens obtained immediately after surgical excision. Tissue specimens obtained from the trunk or extremities showed a greater degree of tissue shrinkage (16.3%) than specimens obtained from the head and neck (10.2%). CONCLUSIONS: Our results support anecdotal suggestions that skin specimens do indeed shrink during frozen section processing. By realizing that frozen section specimens can be expected to show some slight degree of shrinkage, the Mohs surgeon can appreciate situations that might allow greater confidence that a smaller specimen is nonetheless representative of the entire lateral and deep surgical margins.     

Mohs Tissue Mapping and Processing: A Survey Study

BACKGROUND: Mohs micrographic surgery (MMS) is the most reliable, conservative, and tissue-sparing approach to the management of cutaneous malignancies. The concept of MMS is simple, but its technique, which involves a series of suboperations, is complex. OBJECTIVE: To define which techniques of Mohs tissue mapping and processing are presently employed by members of the American College of Mohs Micrographic Surgery and Cutaneous Oncology. METHODS: Five hundred eighty surveys of eight questions regarding different techniques used in Mohs tissue mapping and processing were mailed out to Mohs micrographic surgeons registered with the American College of Mohs Micrographic Surgery and Cutaneous Oncology. A total of 310 responses (53%) were collected between October and December 2002. The results were tabulated and analyzed. RESULTS: Most Mohs micrographic surgeons personally prepare the map of the tissue in relationship to the patient (66.5%). A hand-drawn picture with standard orientations is most frequently used to map and orient a tissue specimen (69.4%). Histotechnicians usually prepare the tissue specimen for cryostat processing (63.5%). A heat extractor and/or tissue cuts or "slits" are the preferred methods used to flatten tissue by 52.9% of respondents. Hematoxylin and eosin is the stain that is most commonly used (82.6%). Approximately 50% of Mohs micrographic surgeons cut the excised specimen from the first stage into two separate pieces. Each tissue piece is then commonly processed into three to six representative serial sections per glass slide (68.1%). These sections are most commonly cut at 5 to 6 microm (53.9%) and less frequently at 4 microm (21.9%). CONCLUSION: There is variability in mapping and processing techniques employed Mohs micrographic surgeons and their histotechnicians. As long as the integrity of each step of Mohs tissue mapping and processing is preserved, the high cure rate of the technique should be maintained.     

Mohs Micrographic Surgery for the Eradication of Phaeohyphomycosis of the Hand

Background. PHAEOHYPHOMYCOSIS is a rare mycotic infection that is caused by dematiaceous fungi requiring surgical excision or long-term use of oral antifungal agents for treatment.
Objective. To report a case of phaeohyphomycosis of the dorsal hand successfully cleared with Mohs micrographic surgery.
Methods. We performed Mohs micrographic surgery on phaeohyphomycosis of the dorsal hand. The fungus was cleared in three stages of surgery. Permanent processing and special stains of the final stage confirmed eradication of the infection.
Results. The patient remained free of the phaeohyphomycosis, without complications, at the 6-month follow-up.
Conclusion. Mohs micrographic surgery is an effective, tissue-sparing technique for the eradication of phaeohyphomycosis, potentially eliminating the need for costly long-term antifungal therapy.     

Presurgical Curettage Appropriately Reduces the Number of Mohs Stages by Better Delineating the Subclinical Extensions of Tumor Margins

Background. Whether presurgical curettage (PC), light curettage performed before Mohs surgery to delineate tumor margin, is appropriate or causes unnecessary removal of normal tissue has not been well established.
Objective. We aim to determine histologically whether PC appropriately increases the size of the stage I specimen or causes unnecessary removal of healthy tissue.
Methods. Before a surgical margin guided by PC was taken, a hypothetical margin determined by visual and tactile assessment alone (no curettage [NC]) was marked outside the clinically defined tumor. Histologic analysis at the NC and the PC margins revealed whether the increase in the stage I specimen as a result of PC was appropriate.
Results. PC appropriately increased the stage I specimen in 21 cases and unnecessarily removed normal tissue in only 1 case. The estimation of tumor margins with PC was 15 times more accurate than with NC (p value = .0012).
Conclusion. For basal cell and squamous cell carcinomas at least 4 mm in diameter, light curettage performed prior to Mohs surgery could better delineate subclinical extensions of the tumor margin and appropriately increase the size of the stage I specimen.     

Novel Technique for Use of Cyanoacrylate in Mohs Surgery

BACKGROUND: Many Mohs procedures involve the handling and manipulating of thin, fragile skin tissue, particularly eyelid skin. After excision of such tissue, proper handling of the tissue becomes critical for tissue orientation and histologic processing. OBJECTIVE: The authors present a novel way to handle thin, friable tissue after excision in Mohs surgery with the direct application of cyanoacrylate onto freshly excised tissue. METHODS: Nonsterile generic cyanoacrylate can be applied along the epidermal surface edge to excised thin tissue sections before inking the margins, sectioning, and processing. CONCLUSIONS: The superglue increases tissue rigidity and provides for easier handling while staining and orienting the tissues. The added glue does not alter tissue integrity and shows minimal artifact upon histologic examination. This technique furthermore is inexpensive and adds little time to the Mohs procedure. Clinical photographs and histologic pictures are presented.     

Role of Multiple Scouting Biopsies before Mohs Micrographic Surgery for Extramammary Paget's Disease

Background. Extramammary Paget's disease (EMPD) frequently extends subclinically, resulting in high recurrence rates after surgical excision. Mohs micrographic surgery (MMS) improves cure rates but may require time-consuming reexcision of subclinical extension. A mechanism to estimate the location and extent of subclinical extension would be helpful.
Objective. To describe and evaluate a technique for multiple scouting biopsies before MMS for EMPD.
Method. A retrospective review of patients at Mayo Clinic who had multiple scouting biopsies before MMS for EMPD without dermal invasion.
Technique. The clinical extent of EMPD is identified. The scouting biopsy sites are determined and documented with photographs. The scouting biopsy specimens are sent for permanent sections. The results of the scouting biopsies help guide the extent of the initial Mohs layer. The tumor is cleared with MMS. An additional 1 mm peripheral margin of tissue is usually submitted for permanent sections.
Results. Multiple scouting biopsies were done in five patients. Four of the five patients had at least one true-positive result. At least one true-negative result was obtained in all five patients. Two patients had at least one false-negative result.
Conclusion. Multiple scouting biopsies before MMS for EMPD without dermal invasion can be a beneficial adjuvant technique.
DAVID L. APPERT, MD, CLARK C. OTLEY, MD, P. KIM PHILLIPS, MD, AND RANDALL K. ROENIGK, MD, HAVE INDICATED NO SIGNIFICANT INTEREST WITH COMMERCIAL SUPPORTERS.     

Mohs Surgical Extirpation of a Basal Cell Carcinoma in a Patient with Familial Multiple Trichoepitheliomas

Background. The success of Mohs surgery relies on the ability to histologically differentiate tumor from the normal background tissue of the patient. In most cases of basal cell carcinoma and nonmelanoma skin cancer, this is a relatively straightforward process. However, in distinction, when only subtle histopathologic features differentiate the background tissue from the tumor of interest, the determination of a tumor-free margin becomes more challenging.
Objective. Our objective is to highlight the histopathologic features that we used to differentiate our patient's near-confluent background of trichoepitheliomas from the basal cell carcinoma that we were extirpating.
Methods. Case report.
Results. A 41-year-old white female with a history of familial multiple facial trichoepitheliomas presented for removal of a basal cell carcinoma on her right lower cutaneous lip. Mohs surgery was used to remove the tumor. The characteristic features of basal cell carcinoma and trichoepithelioma were used to differentiate the basal cell carcinoma that we were removing from the surrounding trichoepitheliomatous neoplasia.
Conclusion. Mohs surgical extirpation of a basal cell carcinoma in a patient with multiple familial trichoepitheliomas requires a clear understanding of the histopathologic features that differentiate a trichoepithelioma from a basal cell carcinoma.
GALEN H. FISHER MD, JOAN MONES, DO, MELISSA GILL, MD, JULIDE TOK CELEBI, MD, AND ROY G. GERONEMUS, MD, HAVE INDICATED NO SIGNIFICANT INTEREST WITH COMMERCIAL SUPPORTERS.     

Microcystic Adnexal Carcinoma Involving a Large Portion of the Face: When Is Surgery Not Reasonable?

Background. We report a case of microcystic adnexal carcinoma (MAC) involving a large portion of the face, one of the largest of any MAC reported thus far in this area, and review the literature regarding the nature of the tumor and available treatments. We also review all of the reported cases of metastases and the possible role of radiation in the etiopathogenesis of this tumor.
Objective. To review the literature about what is known about therapy for MAC and what options are available to patients who have this disease.
Materials and Methods. Case report and review of the literature.
Results. Of the 274 cases of MAC thus far reported, there are 6 cases of metastases, only 1 of which resulted in death.
Conclusion. Mohs surgery should be the treatment of choice for this tumor; however, when extirpation entails sufficiently large morbidity, given the low rate of metastases and mortality, observation is a reasonable alternative.
DANIEL BRIAN EISEN, MD, AND DAVID ZLOTY, MD, HAVE INDICATED NO SIGNIFICANT INTEREST WITH COMMERCIAL SUPPORTERS.     

Characteristics of Mohs Practices in the United States: A Recall Survey of ACMS Surgeons

OBJECTIVE The purpose of this study is to better characterize the typical Mohs practice in the United States and to generate data that may be useful in future practice models.
METHODS A survey was mailed in 2004 to all 599 members of the American College of Mohs Surgery with United States addresses listed in the 2003 directory.
RESULTS Most respondents were part of a single speciality group, in a suburban or urban setting, performed between 501–1,000 cases per year, and had been in practice from 0–5 years. The vast majority of Mohs excisions are for basal cell cancers and squamous cell cancers, followed by melanoma. Primary closure is the most common method of repair, followed by the use of flaps. Only 6% of cases were referred to other specialties for closure. Many surgeons augment their practice with non-Mohs cosmetic procedures.
CONCLUSION The characteristics of current Mohs surgery practices in the United States provides useful data for training programs, potential trainees, workforce issues, statistical modeling systems, and Mohs surgeons in the evaluation of their own practices.     

Margin Involvement after the Excision of Melanoma In Situ: The Need for Complete En Face Examination of the Surgical Margins

BACKGROUND The standard treatment for cutaneous melanoma in situ is surgical excision followed by standard pathologic evaluation. Serial cross-sectioning (bread-loafing) may result in false negative margin examination and higher local recurrence rates than Mohs micrographic surgery, which histologically evaluates the entire surgical margin.
OBJECTIVE To estimate the sensitivity of bread-loafing in detecting residual melanoma in situ at surgical margins.
METHODS A retrospective study was performed including 36 cases of melanoma in situ treated with Mohs surgery with positive margins after initial excision with 5 mm margins. The length of the margin involved with melanoma was measured. The ability of bread-loafing to detect residual tumor was calculated.
RESULTS The average linear extent of tumor at the surgical margin was 1.4 mm. Bread-loafing at 1, 2, 4, and 10 mm intervals would have a 58, 37, 19, and 7% chance of detecting positive margins, respectively. In order to detect 100% of positive margins, bread-loafing would have to be performed every 0.1 mm.
CONCLUSION Bread-loaf cross-sections through excised melanoma specimens are inherently unreliable for detecting residual melanoma at the surgical margins. We recommend complete histologic margin control of the entire surgical margin using en-face tissue orientation (Mohs technique) to reduce the risk of recurrence.     

Linear Basal Cell Carcinoma: Report of Seventeen Cases and Review of the Presentation and Treatment

Background. Linear basal cell carcinoma was first described as a distinct clinical morphologic variant in 1985. Subsequently, twelve cases were reported.
Objective. To review and identify cases of linear basal cell carcinoma in our institutions and determine optimal treatment based on review of our cases and those in the literature.
Methods. Primary basal cell carcinomas treated at the three campuses of Mayo Clinic and the University of Montreal were reviewed retrospectively, as were the twelve cases in the literature.
Results. Seventeen cases of linear basal cell carcinoma were identified. The age and sex ratios were similar to those of patients with standard basal cell carcinomas. Based on the review of the few reported cases of linear basal cell carcinoma (29), the percentage of aggressive histologic subtypes (38%) was increased compared with that in a general population. The average number of Mohs layers required for treatment was higher than that reported for standard basal cell carcinoma, an indication of increased subclinical spread.
Conclusion. Linear basal cell carcinoma is an uncommonly recognized morphologic variant. Based on the small number of cases, these tumors have more aggressive histologic subtypes. Because of the possibility for increased subclinical spread, Mohs micrographic surgery can be considered for treatment. Further studies are needed to confirm these findings.     

Eyelid Sebaceous Carcinoma Masquerading as In Situ Squamous Cell Carcinoma

Background. Sebaceous carcinoma (SC) accounts for 1% to 5.5% of all eyelid malignancies. Diagnosis is often delayed because of its ability to masquerade as other periocular lesions both clinically and histologically.
Objective. To promote a high index of suspicion among Mohs surgeons for SC when managing biopsy-proven in situ squamous cell carcinoma (SCC) of the eyelid, particularly the upper eyelid.
Methods. This is a retrospective case review.
Results. A 77-year-old woman and a 71-year-old man were referred for Mohs micrographic surgery with a diagnosis of upper eyelid in situ SCC on biopsy. Intraoperatively, the presence of clear cell differentiation, in addition to extensive conjunctival involvement, leads to the correct diagnosis of SC. One case was subsequently found to have Muir Torre syndrome.
Conclusion. Early diagnosis of eyelid SC leads to a better outcome and a higher survival rate. Hence, when managing in situ SCC of the eyelids, particularly the upper eyelid, Mohs surgeons should be aware of the possibility of SC and actively look for sebaceous cell differentiation or extensive conjunctival spread.     

Post-Mohs micrographic surgical margin tissue evaluation with permanent histopathologic sections.

BACKGROUND: Incomplete resection of nonmelanoma skin cancer is associated with a relatively high rate of recurrent tumors. Mohs micrographic surgery provides microscopic evaluation of tumor margins to ensure complete excision of nonmelanoma skin cancers at high risk of recurrence. OBJECTIVE: This purpose of this study is to confirm the histologic accuracy of Mohs excision of facial skin cancers by evaluating an additional layer of tissue with permanent histopathologic sections after Mohs excision. METHODS: Two hundred ninety-six Mohs cases were identified, which, after excision, were sent to a single plastic surgeon for reconstruction. This plastic surgeon routinely takes an additional layer and sends for permanent histopathologic evaluation at the time of reconstruction. A review of the pathology reports and tissue specimens on these patients provides valuable data on tumor margins and the effectiveness of the Mohs technique for tumor excision. RESULTS: Two excisions of nodular basal cell cancer were determined by the pathologist to have positive tumor involvement on post-Mohs permanent tissue. On additional review, one specimen was interpreted to be more consistent with follicular epithelium, and the second was verified as a focus of nodular basal cell cancer. CONCLUSION: These data support the high reliability of Mohs surgery for margin control.     

A primer of Mohs micrographic surgery: common indications

Mohs micrographic surgery is a highly effective technique for the removal of some skin cancers. The technique is founded on the idea of excision with minimal margins (sparing normal tissue) and immediate histologic examination of horizontal frozen sections of the specimen while the patient waits. By doing this, a Mohs surgeon is able to examine the margins. If residual tumor is present, subsequent excisions are performed until it is completely removed. In cases of aggressive tumors, recurrent tumors, or in which the lesions are present in high-risk anatomic locations (H-zone of the face) or functionally important areas (e.g., digits, genitals), the preferred treatment is Mohs micrographic surgery.