Mohs Micrographic Surgery Surgical Complication Management

Function

MMS is now the standard treatment for various skin cancers, determined by tumor type, location, and patient characteristics.[5] Although preferences vary across the field, MMS is typically performed in an outpatient setting in an office using a clean technique.[6] After confirming and marking the surgical location, performing site antisepsis, and achieving adequate anesthesia with local anesthesia injections, such as lidocaine, the tissue of concern is excised. Immediate processing of the excised tissue in the laboratory enables the surgeon to examine all tissue margins. Using a tissue mapping technique, the surgeon can determine if the entire lesion has been removed, after which the wound may be closed. Wound closure employs whichever technique is deemed most appropriate for the existing defect.[7] 

Postprocedural clinical follow-up is dictated by the wound closure method. Primary wound closure can typically be cared for by the patient at home until suture removal. In contrast, a tissue-graft closure may require frequent bandage changes and office visits.[8] While complications of MMS are rare (<1%), vigilance is imperative throughout the procedure and healing process; adverse events may occur at different stages.[9]

Issues of Concern

Contact Dermatitis

Before commencing MMS, topical antiseptics like chlorhexidine, povidone-iodine, isopropyl alcohol, chloroxylenol, and hexachlorophene are commonly applied to the surgical site to mitigate the risk of infection.[10] While generally well-tolerated, these antiseptics may lead to irritant or allergic contact dermatitis. Clinicians should know the adverse effects of each antiseptic and be adept at recognizing and managing contact dermatitis associated with their use.[11] Contact dermatitis during MMS may also stem from latex gloves, adhesives in wound dressings, and suture materials, necessitating awareness and appropriate management strategies.[12]

When localized contact dermatitis is suspected in a patient who underwent MMS, it is first important to consider the risks and benefits of treatment. While topical corticosteroids are first-line therapy, their use on surgical sites may delay wound healing and lead to undesirable cosmetic effects like atrophy, especially with prolonged use.[13][14] Prevention of contact dermatitis includes obtaining a comprehensive preprocedural medical history to identify previous triggers and considering alternative antiseptic methods. 

Several options are available if a patient develops a reaction that, if left untreated, may predispose the wound to additional complications, such as infection. Mid- to high-potency topical corticosteroids are recommended for trunk and extremity areas. Low-potency topical corticosteroids are preferred for sensitive sites with thinner skin, such as the eyelids and genitals.[13] Triamcinolone, 0.1% cream, applied once or twice daily for up to a week, is appropriate for trunk or extremity dermatitis. Hydrocortisone 2.5% cream is suitable for eyelid dermatitis.[15] Avoiding direct application of the corticosteroid onto wound edges is advisable. A short course of oral prednisone may be considered for exuberant reactions covering more than 20% of the body surface area.[13] Additional relief measures include emollients, cool compresses, calamine lotion, and colloidal oatmeal baths.[13] Patch testing may be recommended to prevent future reactions for unknown triggers.[13]

Anesthetic Reactions and Vasovagal Episodes

Local anesthetic injection during MMS can lead to infrequent complications such as overdose toxicity, vasovagal syncope, and epinephrine reactions.[16] There are 2 classes of local anesthetics used in MMS: amides, such as lidocaine, and esters, such as benzocaine.[17] Knowing the toxic levels of an anesthetic for each patient is imperative before injecting the medicine. For example, lidocaine, the most commonly used local anesthetic in the United States (US), has a maximum recommended dose set by the US Food and Drug Administration of 4.5 mg/kg at 1% concentration. The maximum dose increases to 7 mg/kg when combined with epinephrine due to its vasoconstrictive properties.[18] Early lidocaine toxicity symptoms include numbness, tongue paresthesia, and dizziness, progressing to restlessness, agitation, and muscle twitching, followed by cardiac arrhythmias, seizures, and coma.[17][19] Bupivacaine poses a higher cardiotoxicity risk, while prilocaine metabolites can cause methemoglobinemia.[17]

Due to the range of serious complications that may arise, MMS practitioners must be trained to recognize and treat local anesthetic toxicity. In most cases, the reaction is transitory and requires no treatment. In others, pausing the procedure at an appropriate stopping point may be sufficient, as well as placing the patient supine and monitoring their status closely until symptoms resolve.[20] However, some cases may require basic life support measures such as airway maintenance and cardiopulmonary resuscitative efforts. In these cases, it is imperative to contact emergency medical services so the patient can be treated and observed in a higher acuity environment.[20]

In some instances, patients may experience palpitations or restlessness due to an adverse reaction to the epinephrine in the injection, even with small doses of local anesthetic.[17] While mild symptoms may warrant monitoring, severe manifestations such as chest pain or shortness of breath necessitate transfer to a higher level of care for close monitoring and assessment of cardiac status.[20] Rarely, patients may exhibit a true allergy to local anesthetics, although more commonly, allergies are attributed to preservatives or metabolites.[21] In an immediate hypersensitivity reaction, access to injectable epinephrine, such as an EpiPen^®, in the office is crucial for prompt administration and management.   

During the injection of local anesthetic or at some point during the procedure, some patients may experience a vasovagal response, marked by a rapid decline in heart rate and blood pressure, potentially leading to syncope.[22] Recognizing prodromal symptoms like lightheadedness, warmth, and nausea is crucial.[22] Healthcare providers should promptly lay the patient in a Trendelenburg position with elevated legs to enhance venous return and perfusion. Other measures include crossing the legs or gripping hands to increase venous return and applying a cool towel to the neck or forehead.[23] In 1 documented case of a patient fainting and becoming unresponsive and hypotensive, ammonia spirits and 0.4 mg of subcutaneous atropine were administered with successful resuscitation, with the patient then transferred to a higher level of care.[24]

Bleeding and Hematoma Formation

During MMS, bleeding and hematoma formation are common complications that can lead to tissue necrosis, infection, and wound dehiscence.[9][25] Before MMS, it is crucial to assess for previous bleeding issues or underlying conditions like liver disease or bleeding disorders that may increase the bleeding risk.[25] Additionally, recognizing the heightened bleeding risk in larger wounds is essential for effective management and preventing complications during the procedure.[9]

To mitigate the risk of bleeding during MMS, it is advisable to discontinue unnecessary anticoagulation or antiplatelet therapy. However, it is generally discouraged to halt such medications in patients requiring them for managing comorbidities like coronary artery disease or for high-risk cases due to the potential risks of thrombosis outweighing bleeding-related complications.[25] Notably, stopping herbal supplements to prevent prothrombotic diseases poses no known risks.[25] Although most patients on anticoagulation or antiplatelet therapy in a multicenter prospective cohort study of 20,821 patients did not develop bleeding complications, a significant proportion of bleeding cases occurred among patients on these medications.[9]

Monitoring blood pressure, especially before the procedure, is also important, as elevated readings may increase the likelihood of bleeding complications.[25] Some suggest deferring surgery for blood pressure readings exceeding 200 mm Hg systolic or 110 mm Hg diastolic until evaluation by a primary physician.[25] Anxiolytics and measures to promote a calm surgical environment can help lower blood pressure.[25] Positioning the surgical site above the heart level and ensuring accessibility to the surgeon can aid intraoperative hemostasis. Additionally, using local anesthetic mixed with epinephrine, if appropriate, temporarily constricts blood vessels, further enhancing intraoperative hemostasis.[25]

In MMS, various hemostatic methods, including manual pressure, electrosurgery, heat cautery, topical hemostatics, and vessel ligation, are employed to manage bleeding from ruptured vessels during the incision, extirpation, and undermining processes.[25] For superficial or dermal oozing, topical caustic agents, electrosurgery, heat cautery, and manual pressure are typically utilized.[25][26] Topical caustic agents coagulate proteins, leading to tissue necrosis and eschar formation. They are typically applied via a cotton tip applicator to a dried wound.[26] Aluminum chloride is most commonly used, but other agents include 20% ferric subsulfate, silver nitrate, and zinc chloride.[26] Noncaustic topical hemostatics, physical or physiological agents, can be applied for deeper oozing wounds or postsurgical preventative measures.[26] Physical agents, including porcine gelatins, microporous polysaccharide hemispheres, hydrophilic polymers with potassium salts, cellulose, and collagen compounds, provide a scaffold for platelet aggregation. Physiological agents such as fibrin, thrombin, and platelet gels promote hemostasis by enhancing the augmentation and propagation phases.[26]

Small vessel bleeding beyond oozing in MMS is effectively managed with electrosurgery or electrocautery, ensuring careful attention to avoid excessive tissue and wound edge charring to prevent adverse impacts on wound healing.[27] Bleeding from vessels greater than 2 mm in diameter necessitates ligation to achieve hemostasis, as other methods may be less secure.[27] Quick and effective ligation is crucial for large vessel hemorrhage, utilizing mosquito or Halsted clamps to clamp the vessel, followed by using a dissolving suture for ligation before removing the clamp.[27] Various suture techniques such as figure-of-eight stitches, mattress sutures, running locked sutures, and double imbricating sutures are employed to control intraoperative bleeding effectively.[27]

Manual pressure is an important technique for managing bleeding during and after MMS. Applying sustained pressure to the wound compresses the tissue and vasculature, promoting platelet aggregation and initiation of the coagulation cascade.[27] Pressure can be applied at any point during surgery, and pressure bandages are commonly used postoperatively, especially in surgeries with increased bleeding risk. Tourniquets may be utilized on extremities if necessary, with proximal tourniquets typically applied to the forearm or distal thigh for up to 2 hours. However, the pain is usually unbearable after several minutes.[28] Surgical gloves can also be repurposed to fashion a tourniquet for finger surgery if needed.[27]

Postoperative bleeding risk peaks within the initial 48 hours following dermatologic surgery.[25] Differentiating between oozing, frank bleeding, or hematoma formation is crucial if a patient reports postoperative bleeding. For minor oozing or slow bleeds, patients should be advised to apply direct pressure to the wound for 15 to 20 minutes, repeating twice if necessary.[25] Persistent bleeding or painful, rapidly expanding masses warrant immediate evaluation to identify and address the source.[25] If bleeding persists despite home measures, reopening the wound may be necessary for appropriate treatment, such as electrosurgery or vessel ligation.[25]

Hematomas, characterized by blood accumulation beneath sutured sites, may necessitate urgent intervention.[29] Expanding hematomas typically manifest with pain, warmth, and a growing mass under the suture site, warranting prompt evaluation and treatment.[25] Periorbital and cervical hematomas are deemed medical emergencies due to their proximity to critical structures and must be evaluated immediately.[25] In such cases, partial or complete wound reopening is advised, with attention to addressing the bleeding source and subsequent closure or secondary intention healing if the wound is contaminated or there is a risk for continued bleeding.[25] Local anesthesia, including lidocaine with or without epinephrine, may be employed, with consideration for epinephrine's vasoconstrictive effects.[25] Aspiration using a 16- or 18-gauge needle can aid in reducing hematoma size and hematoma evacuation.[25] Systemic antibiotics may be prescribed to mitigate the risk of secondary wound infection after hematoma development to prevent secondary wound infection.[25]

After several days, a hematoma transitions into a gelatinous, thick clot, making aspiration impractical and wound reopening potentially traumatic. However, after 7 to 10 days, hematomas liquefy due to fibrinolysis, permitting aspiration or trephination for subungual hematomas.[25] Although evidence is lacking, bromelain, a mixture of proteolytic enzymes derived from pineapple, exhibits fibrinolytic and antithrombotic properties and may have a role in hematoma management.[30] Timely recognition and intervention are crucial to mitigate blood loss and prevent complications such as infection, necrosis, and wound dehiscence.[25] Facial surgeries, such as MMS, often result in bruising extending beyond the surgical site. Counseling patients about potential postoperative swelling and bruising outside the surgical site helps alleviate anxiety and minimizes unnecessary inquiries after clinic hours.[25]

Tissue Necrosis

Necrosis often manifests at the edges of sutured skin when blood flow to the tissue is compromised, a potential outcome of MMS in wounds managed through primary closure, skin flaps, or grafting. For wounds primarily closed, necrotic tissue can be debrided and treated with healing ointments like petrolatum, with regular follow-up until complete healing.[31] Regarding partial- or full-thickness flap necrosis, opinions on management vary; some advocate debridement, while others suggest leaving nonviable tissue until underlying tissue heals. Regardless, regular application of healing ointments is recommended.[31] Scar revision via surgery or grafting may optimize cosmetic outcomes.[31] Effective patient communication, expectation setting, and management of related complications like wound dehiscence or infection are crucial to addressing wound necrosis after MMS.

Infection

Infection is historically one of the most common complications of MMS.[9] In the multicenter prospective cohort study of over 20,000 cases previously mentioned, several ways were identified to reduce infection rates, such as using chlorhexidine as an antisepsis before surgery, wearing sterile gloves, and antibiotic prophylaxis.[9] However, the study observed conflicting outcomes concerning using sterile versus nonsterile gloves and highlighted the potential adverse effects of antibiotic overuse, such as allergy development and antibiotic resistance.[6][9] Additional studies have displayed conflicting evidence on whether postoperative antibiotics prevent surgical site infection.[32]

Antibiotics are not routinely prescribed following most Mohs procedures. However, specific conditions and risk factors may prompt a Mohs surgeon to consider a prophylactic antibiotic regimen. Guidelines published in 2008 in the Journal of the American Academy of Dermatology recommend antibiotics for patients at high risk of a hematogenous total joint infection or high-risk cardiac conditions, especially when the surgical site is infected or oral mucosa is breached.[33] Special considerations are warranted for surgeries involving the lower limbs, groin, lip, and ear and in patients with inflammatory skin diseases.[33] Nonprimary wound closures, such as flaps and grafts, also carry a higher risk of infection and may necessitate antibiotic prophylaxis.[29][33] While topical antibiotics can mitigate surgical site infection risk, their potential for contact dermatitis should be carefully weighed against their benefits, particularly when wounds are left open to heal.[34]

When managing a wound infection, selecting the appropriate treatment plan is critical. The 2014 Infectious Disease Society of America guidelines offer formal recommendations and treatment algorithms for surgical site and soft tissue infections.[35] Incision and drainage are advised for purulent infections, and wound culture and sensitivities are recommended for moderate to severe cases.[35] Empiric antibiotics should be initiated and subsequently adjusted based on culture results.[35] In nonpurulent infections, empiric antibiotics are recommended for all cases, with mild cases managed using oral antibiotics and moderate cases potentially requiring intravenous antibiotics and wound debridement where necrosis has occurred.[35] Hospital evaluation and admission may be necessary for severe infections with necrotic tissue.

Empiric antibiotic selection should prioritize coverage of methicillin-sensitive Staphylococcus aureus (MSSA), the most common culprit in surgical site infections.[36] Cephalexin 500 mg 4 times daily for 1 week is adequate for MSSA coverage.[35] In regions with high methicillin-resistant S aureus (MRSA) incidence or in patients with a history of MRSA infection, doxycycline 100 mg twice daily or trimethoprim/sulfamethoxazole 160/800 mg once or twice daily for 1 week can be used.[35] Clindamycin is an alternative for MRSA coverage, but resistance levels vary.[37] If empiric treatment fails, broadening antibiotic coverage and considering previous infection pathogens are advisable, along with wound culture if possible.

Wound Dehiscence

Wound dehiscence, characterized by the separation of approximated wound edges, is often due to failed wound healing. Wound dehiscence typically manifests approximately 2 weeks after closure and may be primary or secondary.[38][29] Causes such as hematoma, necrosis, or infection should be addressed, considering primary and secondary complications.[29] Risk factors include hematoma formation, advanced age, use of vascular endothelial growth factor and tyrosine kinase inhibitors, infection, and wounds under high tension.[38]

There is no consensus on deciding whether to resuture a dehisced wound. In cases where the wound edge appears fresh and healthy, resuturing may be feasible. Conversely, if the wound edge is fragile and friable, debridement before resuturing may be considered appropriate.[38][39] However, some argue that debridement could remove active fibroblasts and weaken the wound's tensile strength.[38][40] Surgeons differ in their opinions regarding the optimal timing for resuturing following dehiscence, with some reports suggesting that outcomes are worse when wounds are resutured 3 to 5 days after dehiscence.[38] Alternative management strategies include using adhesive strips or allowing the wound to heal by secondary intention.[38] Ultimately, discussing patient goals and expectations is crucial before determining the most suitable management plan for wound dehiscence.

Spitting Sutures

Suture spitting, the extrusion of usually absorbable sutures through the skin surface, typically occurs 2 weeks to 3 months postoperatively but can also happen years after MMS.[41] Common absorbable dermatological sutures include polyglactin 910, poliglecaprone 25, and polydioxanone.[41][42] A management algorithm for spitting sutures was proposed by Thornton et al in 2021 and states that to manage spitting sutures, forceps should be used to remove the visible suture material, trimming it as short as possible without causing further damage if the suture cannot be fully removed. If there are no signs of infection, conservative wound care can be initiated. A wound culture should be obtained in cases of suspected infection, and oral antibiotics targeting S aureus and β-hemolytic streptococci should be started.[41] If an abscess is present, incision and drainage, along with warm compresses, are recommended. In the absence of an abscess, conservative wound care is advised, with antibiotic therapy tailored based on culture results if necessary.[41] Strategies to prevent suture spitting include selecting the appropriate suture type and ensuring deep placement of slower-absorbing sutures.[41]

Scarring

Scarring is an expected outcome from MMS. However, when scarring is more severe or disfiguring than expected, offering patients options for scar revision is crucial. The appropriate scar management approach depends on whether the scar is hypertrophic or if a keloid is suspected. Hypertrophic scars are characterized by their limited growth, which is confined to the size of the original wound. In contrast, keloids are scars extending beyond the boundaries of the original wound.[43]

Massage with emollients and the application of sustained pressure can sometimes effectively manage hypertrophic scars.[43] However, thicker scars and keloids may not respond well to these methods alone. In such cases, intralesional corticosteroid injections are commonly used. Triamcinolone acetonide is a frequently utilized corticosteroid for treating hypertrophic scars and keloids. Typically, 5 to 10 mg/mL is injected every 3 to 6 weeks until stabilization is achieved. For well-established keloids, higher concentrations of triamcinolone, up to 40 mg/mL, may be employed.[43] Potential adverse effects associated with corticosteroid use must be considered. Topical corticosteroids can also be used in the case of thinner scars.[43] 

Intralesional 5-fluorouracil can be used alone or in combination with corticosteroids for treating hypertrophic scars or keloids.[43] Limited evidence supports using imiquimod for keloid resolution, as it aids in collagen breakdown.[43] Silicone tape has been used successfully in the past. Although the exact mechanism is unclear, occlusion is thought to keep the tissue moisturized and affects local keratinocytes and fibroblasts.[43]

Laser therapy is an option for managing suboptimal scarring following MMS. The pulsed dye laser (585 - 595 nm) is commonly used for vascular lesions but has demonstrated benefits in treating hypertrophic scars and keloids.[44] Nd:YAG (1064 nm) laser inhibits collagen formation directly, leading to tissue infarction and sloughing. While hypertrophic scars tend to respond better to this treatment, recurrence rates can vary based on the anatomical location.[45]

Ablative laser techniques like CO₂ (10,600 nm) and erbium:YAG (2940 nm) can also improve hypertrophic scars and keloids after MMS, although they are associated with longer recovery periods.[44] Laser resurfacing has shown efficacy at various stages of scar formation, from pre-suturing to months after surgery.[46] Notably, keloids often resist resolution via laser treatment alone, but combined therapy with intralesional triamcinolone or 5-fluorouracil displays improved results.[44] Nonablative fractional lasers offer another approach known for causing less discomfort and delivering superior results compared to pulsed dye lasers.[44] Among radiotherapy options for hypertrophic scars and keloids, electron beam therapy stands out for its safety and effectiveness.[47]

Surgical intervention is another avenue for revising undesireable scarring outcomes. One approach is to utilize techniques that redistribute tension along a hypertrophied or exaggerated linear scar, such as Z-plasty or W-plasty.[48] By dispersing tension horizontally and vertically along the wound, these methods reduce the risk of contractures, especially if the scar spans a mobile joint.[48] Zig-zag scars tend to be less conspicuous due to their poor light reflection.[48]

Skin grafting is another option for improving scarring after MMS. Split-thickness skin grafts are less prone to necrosis but have higher contraction rates.[48] If contraction occurs, revision surgery using a full-thickness skin graft may be considered despite lower graft survival rates, as they exhibit reduced contracture rates.[48]

Various skin flaps, including local, expanded, distant, regional, and free flaps, offer versatile options for surgical scar revision. Common local flap techniques in MMS include advancement, transposition, and rotation flaps.[48]

Dermabrasion, an abrasive technique that removes the epidermis and superficial dermis, facilitates collagen fiber reorientation in the wound. Ideally performed 6 to 12 weeks after surgery, dermabrasion smoothens wound edges and aids in scar refinement.[48]

Pain

Pain is a potential consequence of MMS, but it is often manageable with over-the-counter medication such as acetaminophen.[49] Patients are usually counseled to avoid nonsteroidal anti-inflammatory agents and aspirin due to increased bleeding risks.[49] Postoperative pain tends to be most intense on the day of surgery and gradually improves over the following days.[49] However, more complex closures like flaps and grafts may increase pain rates.[49] In rare cases of severe pain, narcotics may be prescribed, but if pain worsens over time, it is important to evaluate the patient for potential complications such as hematoma or infection.[49] 

Electrical Hardware Interactions

As technology advances, implantable electronic devices (IEDs) become more common. Some of the most frequently used IEDs include implantable cardioverter defibrillators, pacemakers, deep brain stimulators, spinal stimulators, and cochlear implants.[50] In MMS, achieving hemostasis is crucial, and 2 primary methods are electrosurgery and electrocautery.

Electrosurgery involves the use of electric current passing through a cold-tipped electrode. This current can disperse through the body as in monopolar electrosurgery or flow through the target tissue, returning through a second electrode as in bipolar electrosurgery.[50] A grounding pad may reduce the risk of current dispersal in monopolar electrosurgery. On the other hand, electrocautery is generally considered a safer method of hemostasis as it utilizes heat energy to cauterize vessels and has no electrical current dispersal through the patient. However, it is contraindicated when there is a risk of damaging an IED located directly beneath the surgical site.[50]

While modern IEDs typically pose a low risk of electromagnetic interference during electrosurgery, it is generally recommended to avoid unnecessary risk and instead use electrocautery or bipolar electrosurgery to assist in hemostasis during MMS.[50] In the rare event of electromagnetic interference occurring during MMS, immediate steps should be taken to ensure patient safety. This includes contacting the specialist who placed the implant, monitoring the patient's vital signs and overall condition, and arranging for transfer to a higher level of care for further evaluation. Prompt action is essential to mitigate any potential risks associated with electromagnetic interference and to ensure the patient receives appropriate medical attention.

Clinical Significance

MMS has emerged as the gold standard for treating skin cancer across many scenarios. Mohs surgeons and their staff, involved at any stage of the procedure, must remain vigilant in promptly identifying and addressing potential complications. Timely recognition and intervention can significantly mitigate complications associated with MMS.

Minimizing complications enhances clinical outcomes and fosters trust between patients and healthcare providers. Clear communication, thorough follow-up, and alignment of goals with patients are essential components in managing complications effectively. Acknowledging and taking responsibility for undesirable outcomes is crucial, as well as demonstrating a commitment to achieving satisfactory patient results. To accomplish this, surgeons must comprehensively understand management strategies for each potential complication during MMS procedures.

Enhancing Healthcare Team Outcomes

Effective collaboration among healthcare team members is essential in managing Mohs micrographic surgery (MMS) complications to ensure patient-centered care, optimal outcomes, and safety. While complications may vary in severity, ranging from mild to emergent, the entire healthcare team plays a vital role in addressing them. Mild adverse events, such as contact dermatitis, can be managed by various team members, including advanced practitioners, nurses, and pharmacists, without direct intervention from the Mohs micrographic surgeon. However, prompt communication and collaboration with the surgeon are crucial for more severe complications like postoperative bleeding or infection. The surgeon's expertise guides the team in implementing appropriate interventions and coordinating follow-up care, whether scheduling additional procedures or providing supportive measures. Effective interprofessional communication ensures that all team members are aligned in managing complications and supporting the patient through the process, whether through phone conversations, in-person consultations, or follow-up visits. This collaborative approach enhances patient safety, improves outcomes, and comprehensively optimizes team performance in addressing MMS complications.