204: Mohs Micrographic Surgery Flashcards
What is the fundamental advantage of Mohs Micrographic Surgery (MMS)?
The fundamental advantage of MMS is the microscopic analysis of the complete surgical margin.
How does beveled excision in Mohs surgery differ from standard excision?
Beveled excision in Mohs surgery examines the entire deep and peripheral surgical margin in a single plane, while standard excision does not provide this comprehensive analysis.
What is the typical setting for performing Mohs surgery?
Mohs surgery is usually performed as an office-based procedure under local anesthesia.
What is the importance of histopathologic analysis in Mohs surgery?
Histopathologic analysis is crucial as it relies on accurate interpretation of margin status and optimal histologic processing with robust quality control to ensure successful outcomes.
What is the typical angle used for tangential or beveled excision in Mohs surgery?
The typical angle used for tangential or beveled excision in Mohs surgery is 45 degrees.
What is the role of histopathologic analysis in Mohs surgery?
Histopathologic analysis in Mohs surgery is crucial for determining margin status and ensuring that all cancerous cells are removed, which is essential for successful treatment outcomes.
What type of anesthesia is typically used during Mohs surgery?
Mohs surgery is usually performed under local anesthesia, allowing for patient comfort during the procedure.
What is the significance of en face sections in Mohs surgery?
En face sections are significant in Mohs surgery because they allow for the examination of the entire surgical margin in a single plane, improving the accuracy of margin assessment.
What are the implications of false-negative surgical margins in Mohs surgery?
False-negative surgical margins can lead to incomplete removal of cancerous tissue, increasing the risk of recurrence and necessitating further treatment.
What factors contribute to the success of Mohs surgery?
The success of Mohs surgery relies on: 1. Accurate interpretation of histopathologic margin status 2. Optimal histologic processing 3. Robust quality control.
Why is Mohs surgery considered the standard of care for BCC and SCC in certain cases?
Mohs surgery is considered the standard of care for Basal Cell Carcinoma (BCC) and Squamous Cell Carcinoma (SCC) with a high risk of recurrence or in sensitive anatomic locations due to its ability to ensure complete tumor removal while preserving surrounding healthy tissue.
What is the importance of quality control in the histologic processing of tissue in Mohs surgery?
Quality control in histologic processing is important in Mohs surgery to ensure that the tissue is processed accurately, which is critical for the reliable interpretation of margins and ultimately affects the success of the surgery.
What are the risk factors that would predict microscopic tumor extension in a patient with BCC on the nose?
Risk factors include poorly defined clinical margins, diameter greater than 2 cm, and location on the high-risk ‘H’ zone of the face, which includes the nose.
What are the recommended surgical margins for nodular and infiltrative/micronodular basal cell carcinoma (BCC)?
The recommended surgical margins are: - 4 mm for nodular BCC - 5-10 mm for infiltrative and micronodular BCC, which may require excision of underlying muscle, cartilage, and periosteum.
What is the long-term recurrence rate for primary and recurrent basal cell carcinoma (BCC) with high-risk features?
The long-term recurrence rates are: - 1-4% for primary BCC with high-risk features - 4-8% for recurrent BCC.
How does Mohs surgery compare to standard excision in terms of recurrence rates for basal cell carcinoma (BCC)?
Mohs surgery results in a recurrence rate that is 3-4 fold lower than standard excision for both primary and recurrent BCC.
What factors are associated with adverse outcomes in squamous cell carcinoma (SCC)?
Four factors strongly associated with adverse outcomes in SCC include: 1. Diameter greater than 2 cm 2. Depth of invasion below subcutaneous adipose 3. Perineural invasion 4. Poor histologic differentiation.
What is the recurrence rate for primary squamous cell carcinoma (SCC) after standard excision compared to Mohs surgery?
The recurrence rates are: - Up to 8.1% after standard excision - 3.1% after Mohs surgery.
What is the significance of perineural invasion in squamous cell carcinoma (SCC)?
SCC with perineural invasion was found to metastasize in 47% of cases after standard excision compared with 8.3% of cases after Mohs surgery, indicating a higher risk of metastasis with perineural invasion.
What factors would increase the risk of local recurrence and nodal metastasis in a patient with SCC on the ear?
Factors include diameter greater than 2 cm, depth of invasion below subcutaneous adipose, perineural invasion, and poor histologic differentiation.
What is the recurrence rate for primary SCC treated with Mohs compared to standard excision?
The recurrence rate for primary SCC is up to 8.1% after standard excision and 3.1% after Mohs surgery.
What is the appropriate surgical margin for nodular BCC?
The appropriate surgical margin for nodular BCC is 4 mm.
Why might Mohs surgery be particularly beneficial for a patient with SCC on the lip?
Mohs surgery is beneficial due to the increased risk of subclinical extension and incomplete excision in SCC, especially in high-risk locations like the lip and in immunosuppressed patients.
What is the long-term recurrence rate for primary BCC with high-risk features treated with Mohs?
The long-term recurrence rate for primary BCC with high-risk features treated with Mohs is 1-4%.
What is the recurrence rate for previously treated SCC after Mohs compared to standard excision?
The recurrence rate for previously treated SCC is 23.3% after standard excision and 10% after Mohs surgery.
What are the four factors strongly associated with adverse outcomes in SCC?
The four factors are diameter greater than 2 cm, depth of invasion below subcutaneous adipose, perineural invasion, and poor histologic differentiation.
Why might Mohs surgery be particularly beneficial for a patient with a 3 cm SCC on the lip?
Mohs surgery is beneficial due to the increased risk of subclinical extension and incomplete excision in SCC, especially in high-risk locations like the lip.
What are the recommended surgical margins for nodular and infiltrative/micronodular basal cell carcinoma (BCC)?
- Nodular BCC: 4 mm - Infiltrative and Micronodular BCC: 5-10 mm; more likely requires excision of underlying muscle, cartilage, and periosteum.
What is the long-term recurrence rate for primary BCC with high-risk features after Mohs surgery?
The long-term recurrence rate for primary BCC with high-risk features is 1-4% after Mohs surgery.
How does the recurrence rate of Mohs surgery compare to standard excision for BCC?
Mohs surgery results in a recurrence rate that is 3-4-fold lower than standard excision for both primary and recurrent BCC.
What factors are associated with a more than twofold reduction in recurrence rate after Mohs for BCC?
Factors associated with a more than twofold reduction in recurrence rate after Mohs include: - 1-cm diameter - Location on H zone - Infiltrative or micronodular histologic pattern.
What is the recurrence rate for primary squamous cell carcinoma (SCC) after standard excision and after Mohs surgery?
- Primary SCC: Up to 8.1% after standard excision and 3.1% after Mohs surgery.
What are the four factors strongly associated with adverse outcomes in SCC?
The four factors associated with adverse outcomes in SCC are: 1. Diameter greater than 2 cm 2. Depth of invasion below subcutaneous adipose 3. Perineural invasion 4. Poor histologic differentiation.
How does the presence of risk factors affect local recurrence rates in SCC?
The presence of risk factors increases local recurrence rates: - 0.6% with no risk factors - 5% with 1 risk factor - 21% with 2-3 risk factors.
What is the significance of perineural invasion in SCC cases?
SCC with perineural invasion was found to metastasize in 47% of cases after standard excision compared with 8.3% of cases after Mohs surgery.
What are the implications of host immunosuppression in SCC treatment?
Host immunosuppression is a risk factor for adverse outcomes in SCC that may benefit from Mohs surgery, particularly in high-risk locations such as the lip, ear, temple, and penile skin.
What is the differential efficacy of Mohs surgery compared to standard excision for SCC?
The differential efficacy of Mohs surgery over standard excision is most pronounced for: - Tumors in the H zone of the face - Tumors greater than 2 cm - Aggressive histologic features.
What are the recommended treatments for SCC in situ and why?
For SCC in situ, other forms of treatment besides Mohs should be considered due to minimal depth of invasion.
What is the most common technique used for melanoma detection during Mohs surgery?
The most common technique is Mohs using immunohistochemical stains for melanoma antigen recognized by T cells (MART-1) on rapidly processed frozen sections.
What are the limitations of using MART-1 in melanoma detection?
Its use is limited to melanoma in situ and superficially invasive melanoma (Breslow depth <1mm) with minimal risk of metastasis.
What alternative methods have been proposed for melanoma treatment besides Mohs?
Other investigators have proposed staged excision with formalin-fixed sections or a combination of perpendicular (bread-loaf) and en face frozen sections during Mohs, both achieving high cure rates of >95%.
What is the recurrence rate of dermatofibrosarcoma protuberans (DFSP) after conventional excision compared to Mohs?
Local recurrence after conventional excision was 6% compared to 1% for Mohs.
What types of tumors are likely to benefit most from Mohs surgery?
Mohs is likely to provide the most therapeutic benefit for tumors with broad and unpredictable subclinical extension, such as microcystic adnexal carcinoma or tumors in critical anatomic locations like sebaceous carcinoma of the eyelid.
What are the healing characteristics of defects resulting from Mohs surgery?
Defects resulting from Mohs may be suited to healing without reconstruction because it often creates wounds of shallow depth that may be conducive to second intent healing.
What technique is most commonly used for melanoma in situ during Mohs surgery?
Mohs surgery using immunohistochemical stains for melanoma antigen recognized by T cells (MART-1) on rapidly processed frozen sections is most commonly used.
Why might staged excision be beneficial for superficial melanoma on chronically sun-exposed skin?
Staged excision is beneficial because nearly 20% of superficial melanomas on chronically sun-exposed skin have subclinical extension beyond the recommended 5-mm margin of grossly uninvolved skin.
What are the considerations for treating SCC in situ, and why might Mohs surgery not be the preferred option?
For SCC in situ, other forms of treatment besides Mohs should be considered due to the minimal depth of invasion.
What complications arise from using frozen sections in the detection of melanoma?
Artifacts introduced on frozen sections complicate the detection of intraepidermal melanocytes and decrease the sensitivity of melanoma detection.
What is the most common technique used in Mohs surgery for melanoma, and what are its limitations?
The most common technique is Mohs using immunohistochemical stains for melanoma antigen recognized by T cells (MART-1) on rapidly processed frozen sections, limited to melanoma in situ and superficially invasive melanoma (Breslow depth <1mm) with minimal risk of metastasis.
What alternative methods have been proposed for excising melanoma, and what are their success rates?
Staged excision with formalin-fixed sections or a combination of perpendicular (bread-loaf) and en face frozen sections during Mohs can achieve high cure rates of >95%.
Why might staged excision be beneficial for patients with superficial melanoma on chronically sun-exposed skin?
Nearly 20% of patients with superficial melanoma on chronically sun-exposed skin may have subclinical extension beyond the recommended 5-mm margin of grossly uninvolved skin, making staged excision beneficial.
What is dermatofibrosarcoma protuberans (DFSP), and how does it behave in terms of metastasis and recurrence?
Dermatofibrosarcoma protuberans is a slowly progressive tumor that rarely metastasizes but has broad subclinical extension and a high recurrence rate after conventional excision.
What are the local recurrence rates for DFSP after conventional excision compared to Mohs surgery?
Local recurrence after conventional excision was 6% compared to 1% for Mohs surgery.
What criteria determine the suitability of Mohs surgery for solid cancers?
Any solid cancer with contiguous growth that can be identified on frozen histopathologic sections and is accessible from the external surface of the body can be treated with Mohs.
In what scenarios is Mohs surgery likely to provide the most therapeutic benefit?
Mohs is likely to provide the most therapeutic benefit for tumors with broad and unpredictable subclinical extension, such as microcystic adnexal carcinoma, or tumors in critical anatomic locations like sebaceous carcinoma of the eyelid or EMPD.
What types of tumors have been treated with Mohs surgery?
Mohs has been used for treatment of adnexal carcinoma, apocrine and eccrine carcinoma, leiomyosarcoma, Merkel cell carcinoma, and mucinous carcinoma.
What are the healing characteristics of defects resulting from Mohs surgery?
Defects resulting from Mohs may be suited to healing without reconstruction because they often create wounds of shallow depth that may be conducive to second intent healing.
What are the advantages of using second intent healing in Mohs surgery for certain wounds?
Second intent healing in Mohs surgery can lead to reliable functional and cosmetic results, particularly for wounds on thin skin areas like the eyelid or ear, and concave surfaces such as the medial canthus and anterior surface of the ear. In appropriately selected patients, this method results in patient satisfaction equivalent to primary surgical repair.
What are the most common adverse events associated with Mohs surgery?
The most common adverse events associated with Mohs surgery include:
1. Infections (0.40%)
2. Impaired wound healing including dehiscence and necrosis (0.14%)
3. Postoperative bleeding or hematoma (0.11%)
What is the overall adverse event rate for Mohs surgery?
The overall adverse event rate for Mohs surgery is 0.72%, with a serious adverse event rate of 0.02%.
What considerations should be made for patients on anticoagulants undergoing Mohs surgery?
Patients on anticoagulants such as aspirin, warfarin, or direct factor Xa inhibitors have a modestly increased risk of minor bleeding complications; however, this is not a contraindication to Mohs surgery. Patients are advised to continue their prescribed anti-coagulation therapy during and after surgery.
When is antibiotic prophylaxis recommended before Mohs surgery?
Antibiotic prophylaxis before Mohs surgery is generally not required, except for patients at high risk of complications from infective endocarditis (e.g., those with prosthetic heart valves or significant congenital heart disease) and in cases of breach of the oral mucosa or for patients with total knee or hip replacements at increased risk of hematogenous total joint infection.
A patient with a history of cardiac transplant and significant valvular disease is undergoing Mohs surgery. Should antibiotic prophylaxis be considered?
Yes, antibiotic prophylaxis is recommended for patients at high risk of complications of infective endocarditis, such as those with significant valvular disease.
A patient with a history of total knee replacement is undergoing Mohs surgery. Should antibiotic prophylaxis be considered?
Yes, antibiotic prophylaxis is recommended for patients with total knee or hip replacement who are at increased risk of hematogenous total joint infection.
A patient with a history of infective endocarditis is undergoing Mohs surgery. Should antibiotic prophylaxis be considered?
Yes, antibiotic prophylaxis is recommended for patients with a history of infective endocarditis.
What are the advantages of using second intent healing in Mohs surgery for certain patients?
In appropriately selected patients, healing of Mohs surgical defects by second intent results in patient satisfaction that is equivalent to primary surgical repair. This method is particularly effective for wounds on thin skin areas such as the eyelid or ear, and on concave surfaces like the medial canthus and anterior surface of the ear.
What are some common adverse events associated with Mohs surgery, and what are their rates?
The most common adverse events in Mohs surgery include:
1. Infections: 0.40%
2. Impaired wound healing (including dehiscence and necrosis): 0.14%
3. Postoperative bleeding or hematoma: 0.11%
Overall, the adverse event rate is 0.72% and the serious adverse event rate is 0.02%.
How does the use of local anesthetic contribute to the safety of Mohs surgery?
The use of local anesthetic, along with the lack of significant volume shift or cardiovascular stress after cutaneous surgery, likely contributes to the overall safety of Mohs surgery.
What is the recommendation for patients on anticoagulants undergoing Mohs surgery?
Patients on anticoagulants such as aspirin, warfarin, or direct factor Xa inhibitors are advised to continue their prescribed anti-coagulation therapy during and after Mohs surgery, as having these medications is not a contraindication to the procedure, although they may have a modestly increased risk of minor bleeding complications.
In what situations is antibiotic prophylaxis recommended before Mohs surgery?
Antibiotic prophylaxis is generally not required before Mohs surgery, except in specific cases such as:
1. Patients at high risk of complications of infective endocarditis (e.g., those with prosthetic heart valves, prior history of infective endocarditis, or significant congenital heart disease).
2. Breach of the oral mucosa.
3. Patients with total knee or hip replacement who are at increased risk of hematogenous total joint infection.
What surgical techniques have been popularized by Mohs surgeons for cutaneous reconstruction?
Mohs surgeons have popularized several advances in cutaneous reconstruction, including:
1. Buried vertical mattress suture
2. Modern bilobe transposition skin flap on the nose
3. Use of cartilage grafts
4. Multistaged interpolation flaps
What is the overall adverse event rate for Mohs surgery, and how does it compare to serious adverse events?
The overall adverse event rate for Mohs surgery is 0.72%, while the serious adverse event rate is significantly lower at 0.02%. This indicates that Mohs surgery is a remarkably safe procedure with low complication rates.
What factors contribute to patient satisfaction in Mohs surgery when using second intent healing?
Factors contributing to patient satisfaction in Mohs surgery using second intent healing include reliable functional and cosmetic results, particularly in appropriately selected patients, and the ability to achieve outcomes equivalent to primary surgical repair.
What are the implications of using immediate surgical repair techniques in Mohs surgery?
Immediate surgical repair techniques, such as linear closure, skin grafts, or skin flaps from adjacent or interpolated tissue reservoirs, are now used more often than second intent healing.
What is the significance of the low complication rates associated with Mohs surgery?
The low complication rates associated with Mohs surgery, with an overall adverse event rate of 0.72% and serious adverse event rate of 0.02%, signify that it is a remarkably safe procedure, making it a preferred option for skin cancer treatment.
How do Mohs surgeons approach the use of antibiotic prophylaxis in their practice?
Mohs surgeons generally use antibiotic prophylaxis sparingly and only in patients who meet specific criteria, such as those at high risk for infective endocarditis or those with certain surgical conditions.
What are the overall cost benefits of Mohs surgery compared to standard excision?
Overall costs of Mohs surgery may be 20-30% less than standard excision.
What organizations published the Appropriate Use Criteria for Mohs surgery?
The Appropriate Use Criteria for Mohs surgery were published by the AAD, American College of Mohs Surgery, American Society for Dermatologic Surgery, and American Society for Mohs Surgery.
What factors are defined in the Appropriate Use Criteria for Mohs surgery?
The Appropriate Use Criteria define tumor-specific and patient-specific factors for which Mohs surgery is deemed to be either appropriate, uncertain, or inappropriate.
What is the significance of the risk area in determining the appropriateness of Mohs surgery?
The risk area is crucial in determining the appropriateness of Mohs surgery, as it categorizes the diagnosis into high, medium, or low risk.
How does the clinical diameter of a tumor affect the use of Mohs surgery according to the criteria?
The clinical diameter of a tumor influences the appropriateness of Mohs surgery, with different risk areas and tumor types being scored as appropriate (A) or inappropriate (U) based on size categories: <0.5 cm, 0.6-1 cm, 1.1-2 cm, and >2 cm.
What are the implications of high-risk features for squamous cell carcinoma (SCC) in Mohs surgery?
High-risk features for SCC, such as perineural invasion or infiltrative features, indicate a need for careful consideration in the use of Mohs surgery.
What is the role of patient-specific factors in the decision-making process for Mohs surgery?
Patient-specific factors play a significant role in the decision-making process for Mohs surgery, as they help determine whether the procedure is appropriate, uncertain, or inappropriate.
What types of basal cell carcinoma (BCC) are considered in the Mohs surgery criteria?
The Mohs surgery criteria consider various types of BCC, including primary nodular BCC, primary aggressive BCC, primary superficial BCC, and recurrent BCC (both superficial and not superficial).
What is the importance of defining high-risk areas in the context of Mohs surgery?
Defining high-risk areas is important in Mohs surgery as it helps identify regions where tumors are more likely to recur or have aggressive behavior.
How does the classification of tumors by clinical diameter impact the treatment approach in Mohs surgery?
The classification of tumors by clinical diameter impacts the treatment approach in Mohs surgery by determining the risk area and guiding whether the surgery is deemed appropriate or inappropriate.
What type of excision is used in Mohs Micrographic Surgery?
Tangential or beveled excision.
What are the high-risk areas for Mohs surgery according to the AUC?
High-risk areas include the H zone of the face: eyelids, eyebrows, nose, lips, chin, ears, periauricular skin, and temples, as well as genitalia, hands, feet, ankles, nipple, and areola region.
What is the appropriate surgical margin for nodular BCC?
4 mm for nodular BCC.
Give 2 risk factors that predict microscopic tumor extension of BCC.
- Poorly defined clinical margins
- Diameter greater than 2cm.
Give 2 factors that appear strongly associated with adverse outcomes of SCC.
- Diameter greater than 2cm
- Depth of invasion below subcutaneous adipose.
What are the medium-risk areas included in the Appropriate Use Criteria?
Medium-risk areas include cheeks, forehead, jawline, scalp, neck, and pretibial surfaces.
T or F. Skin cancers requiring 5 stages is common.
False. Skin cancers requiring 4-6 stages is uncommon.
T or F. Impaired wound healing is the most common adverse event of MMS.
False. Infections are the most common adverse events.
A patient with a 1.5 cm basal cell carcinoma (BCC) on the forehead is being evaluated for Mohs surgery. Is this location considered high, medium, or low risk?
The forehead is considered a medium-risk area according to the Appropriate Use Criteria.
A patient with a basal cell carcinoma (BCC) on the chin is undergoing Mohs surgery. What are the high-risk areas for BCC according to the Appropriate Use Criteria?
High-risk areas include the H zone of the face (eyelids, eyebrows, nose, lips, chin, ears, periauricular skin, temples), genitalia, hands, feet, ankles, nipple, and areola region.
A patient with a basal cell carcinoma (BCC) on the trunk is being evaluated for Mohs surgery. Is this location considered high, medium, or low risk?
The trunk is considered a low-risk area according to the Appropriate Use Criteria.
A patient with a basal cell carcinoma (BCC) on the scalp is undergoing Mohs surgery. Is the scalp considered a high, medium, or low-risk area?
The scalp is considered a medium-risk area according to the Appropriate Use Criteria.
A patient with a basal cell carcinoma (BCC) on the jawline is undergoing Mohs surgery. Is the jawline considered a high, medium, or low-risk area?
The jawline is considered a medium-risk area according to the Appropriate Use Criteria.
Is it true or false that skin cancers requiring 5 stages is common?
False. Skin cancers requiring 4-6 stages is uncommon.
What are 2 risk factors that predict microscopic tumor extension of BCC?
- Poorly defined clinical margins
- Diameter greater than 2cm.
What are 2 factors that appear strongly associated with adverse outcomes of SCC?
- Diameter greater than 2cm
- Depth of invasion below subcutaneous adipose.
Is it true or false that impaired wound healing is the most common adverse event of MMS?
False. Infections are the most common adverse events.
Give 1 example of patients that may need antibiotic prophylaxis for Mohs.
Patients with a history of prosthetic heart valves or those undergoing Mohs surgery in high-risk areas may need antibiotic prophylaxis.
What are the medium risk areas included in the Appropriate Use Criteria?
Medium-risk areas include:
- Cheeks
- Forehead
- Jawline
- Scalp
- Neck
- Pretibial surfaces.
Who are considered patients at high risk of infective endocarditis?
Patients at high risk include those with total knee or hip replacements.
What are the characteristics of patients at high risk for infective endocarditis?
Patients at high risk for infective endocarditis include those with total knee or hip replacements.
Which areas of the body are considered medium risk for surgical procedures?
Medium risk areas include the cheeks, forehead, jawline, scalp, neck, and pretibial surfaces.
