Key characteristics of basal cell carcinoma with large subclinical extension

Mohs micrographic surgery for keratinocyte carcinomas: clinicopathological predictors of the number of stages

Background

The number of Mohs stages needed to remove a keratinocyte carcinoma affects resource use, expenses, and repair complexity. This study aimed to identify clinicopathological predictors associated with increased or decreased stages and areas for further research.

Methods

A retrospective review was conducted from a single private practice with two Mohs surgeons of 2788 consecutive Mohs cases between January 2017 and December 2021, analyzing the average number of stages taken versus national norms (P = 0.21) and subgroups using unpaired t tests (*<0.05).

Results

Several tumor features were significantly associated with fewer stages: squamous cell carcinomas, Mohs appropriate use criteria score of 7 or 8, preoperative size <0.25 cm2, tumors on the lips and extremities (including hands/fingers), and smoking. Clinicopathological features significantly associated with more stages included Mohs appropriate use criteria score of 9, recurrent skin cancers, basal cell carcinomas, tumor size of 2.25-3.99 cm2, cancers on ears, solid organ transplant patients, treatment delays >180 days, and patients ≥90 years old.

Conclusions

Significant predictors exist for both increased and decreased numbers of Mohs micrographic surgery stages required to eradicate a tumor, which may help Mohs surgeons facilitate, plan, and allocate resources more effectively. Areas for further research in Mohs micrographic surgery are identified.

Correlation of basal cell carcinoma subtype with histologically confirmed subclinical extension during Mohs micrographic surgery: A prospective multicenter study

BACKGROUND

Traditionally "aggressive" histologic subtypes (HSs) of basal cell carcinoma (BCC) are more likely to quantitatively exhibit subclinical extension (SCE), requiring more stages during Mohs micrographic surgery (MMS) and, therefore, larger margins upon excision. However, the tendency for SCE has never been compared between HSs of BCC in a prospective manner.

OBJECTIVE

To prospectively correlate the HS of BCC with the likelihood of SCE as defined by the number of MMS stages required to clear the tumor.

METHODS

In a prospective, multicenter study involving 17 Mohs surgeons in 16 different practices across the United States, data regarding 1686 cases of BCC undergoing MMS were collected. Patient demographics, tumor characteristics, number of MMS stages required for tumor clearance, and specific BCC subtypes noted on both index biopsy and the final MMS stage were recorded.

RESULTS

Analysis of the average number of MMS stages for each HS required to clear tumor revealed 2 distinct degrees of SCE (P < .0001): high (higher than average) risk of SCE (1.9 stages, 1.0 SD) and low (lower than average) risk of SCE (1.6 stages, 0.9 SD). Subtypes of BCC within the high category were morpheaform (2.1), infiltrative (1.9), metatypical (1.9), mixed (1.8), and superficial (1.8). The low category included BCC subtypes of basosquamous (1.6), micronodular (1.6), nodular (1.6), and unspecified (1.5). Three hundred twenty-four cases (22.0%) manifested HS drift or a change in subtype from index biopsy to the final MMS stage. Superficial BCC was the only subtype that showed an increase in prevalence from index biopsy to the final MMS stage (from 16.0% to 25.8%; P < .0002).

LIMITATIONS

HSs from index biopsy may not be representative of all HSs present, resulting in sampling bias.

CONCLUSION

SCE of superficial BCC was as likely as SCE of BCC subtypes that are considered "aggressive" and are deemed "appropriate" for MMS by the appropriate use criteria. Our study also found that when HS drift occurs, the most likely subtype to extend subclinically is superficial BCC.

Clinicopathological factors influencing the number of stages of Mohs surgery for basal cell carcinoma

Background

Mohs Micrographic Surgery (MMS) is commonly used to treat high-risk basal cell carcinoma (BCC).

Objectives

Correlate clinicopathologic preoperative features with the number of MMS stages (primary endpoint) and margins (secondary endpoint) required for BCC complete excision.

Methods

We retrospectively analyzed BCCs treated by MMS in a 2-year period at the study’s institution. Variables studied included the patient gender, age, immune status, lesion size, location, if it was a primary, recurrent, or persistent tumor, histopathologic characteristics, number of surgical stages, and amount of tissue excised.

Results

116 BCCs were included. The majority (61.2%, n = 71) required a single-stage surgery for complete clearance, requiring a final margins of 3.11 ± 2.35 mm. Statistically significant differences between locations in different high-risk areas (periocular, perioral, nose, ear) and the number of MMS stages required for complete excision (p = 0.025) were found, with periocular tumours requiring the highest mean of stages (2.29 ± 0.95). An aggressive histopathology significantly influenced the number of MMS stages (p = 0.012). Any significant relation between clinicopathological features and variation in the final surgical margins was found, just certain tendencies (male patients, persistent tumor, periocular location, and high-risk histopathological tumors required larger margins). Neither patient age or tumor dimension correlated significantly with both number of MMS stages and final surgical margins.

Study limitations

Limitations of this study include its single-center nature with a small sample size, which limits the value of conclusions.

Conclusion

Main factors related to a greater number of MMS stages were periocular location and high-risk histopathological subtype of the tumor.

Surgical margins required for basal cell carcinomas treated with Mohs micrographic surgery according to tumor features

BACKGROUND

Basal cell carcinomas (BCCs) with high-risk features are preferably treated by Mohs micrographic surgery. Studies have shown clinicopathologic characteristics that may predict more stages required for clearance. However, few studies have correlated such factors with the number of millimeters removed per stage.

OBJECTIVE

To determine margins necessary for BCC clearance according to tumor features, especially for tumors less than 6 mm, and to suggest initial margins for Mohs micrographic surgery and margins for wide local excision.

METHODS

Retrospective analysis of 295 consecutive Mohs micrographic surgeries for primary BCCs. Variables analyzed included patient age, sex, immunostatus, lesion size, location, histologic subtype, borders, stage number, and millimeters excised per stage.

RESULTS

BCCs less than 6 mm had a clearance rate of 96% with 3-mm margins. In adjusted multivariable analysis, superficial, micronodular, infiltrative, and morpheaform subtypes were associated with larger margins, whereas clinically well-defined tumors were associated with smaller margins.

LIMITATIONS

Because of the limited sample of certain subtypes, a 3-mm margin is better suited for nodular tumors.

CONCLUSION

These data help guide initial Mohs micrographic surgery and wide local excision margins required for tumor clearance according to tumor features. Nodular BCCs less than 6 mm may be cleared with 3-mm margins instead of the current 4-mm margin recommendation.