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Mohs’ Surgery for Facial Soft Tissue Malignancies: Successes and Limitations – Reconstructive Surgeon Perspective

Marek K. Dobke, M.D.

Division of Plastic Surgery, Department of Surgery,

University of California San Diego

Corresponding author:

Marek Dobke, M.D.

Division of Plastic Surgery UCSD

200 West Arbor Drive

San Diego, CA 92103

USA

e-mail: mdobke@ucsd.edu

ABSTRACT

Background: Goals for the treatment of skin and other facial soft tissue malignancies include completeness of removal, minimal functional disability and good aesthetic outcome. With increasing standards for the quality assurance and the demand for cost-effectiveness, assessment of resource-consuming treatment modalities, especially those involving multidisciplinary approaches, seems appropriate.

Objective: The purpose of this study was to review the strategy of management and the approaches to the repair of facial defects following Mohs’ micrographic surgery from the plastic surgeon’s point of view.

Method: Retrospective review of personal experience based on 1500 patients treated between 1989 and 2011, as well as current plastic surgery literature.

Results and Conclusions: Teamwork with the Mohs surgeon, recognition of the post-Mohs’ procedure defect components, especially those non-conforming to “aesthetic units,” and familiarity with reconstructive techniques are essential for the multidisciplinary practice success.  Local and systemic conditions, and some subsets of malignancies prone to reoccurrence, merit further study of oncologically adequate surgical margins, which micrographic surgery approaches may not always secure.

Representative cases illustrating the impact of the above factors on reconstruction and pitfalls of restorative surgery approaches are presented.

As a part of a multidisciplinary team we have been consulted on 1,500 patients with soft tissue malignancy of the face and neck during the last 22 years. In the earlier years (1989-1996) of our cooperation with dermatological Mohs’ surgeons, recurrent facial skin malignancy and recurrent facial skin cancer were the most frequent problems among patients referred for counseling regarding possible reconstructive procedures prior to micrographic surgery (1). Subsequently, the vast majority of patients required reconstructive surgery by a plastic surgeon for the repair of post-Mohs procedure defects. Currently, indications for Mohs surgery have broadened. Micrographic surgery is recommended not only for basal and squamous cell carcinomas (BCCs and SCCs) of the face and neck with specific characteristics but also for dermatofibrosarcoma, extramammary Paget’s disease, Merkel cell carcinoma, sebaceous carcinomas, and microcystic adnexal carcinomas (table 1)(2). The use of micrographic surgery to treat melanoma remains controversial: atypical melanocytes are difficult to assess using frozen sections, however, recently developed immunostains allow intraoperative visualization melanocytic tumor borders (2,3).

Table 1.

Histological types of the head and neck tumors amenable for treatment by means of

Mohs’s surgery.

  1. basal cell carcinoma
  2. squamous cell carcinoma
  3. certain types of melanoma (e.g., lentigo maligna, desmoplastic melanoma)
  4. dermatofibrosarcoma protuberans, malignant fibrous histiocytoma
  5. extramammary Paget’s disease
  6. microcystic adnexal carcinoma
  7. adenoid cystic carcinoma
  8. Merkel cell carcinoma
  9. sweat glands carcinomas (besides microcystic adnexal and adenoid cystic carcinomas)
  10. sebaceous gland carcinoma
  11. leiomyosarcoma
  12. malignant granular cell tumor
  13. angiosarcoma
  14. lymphoepithelial-like carcinoma
  15. malignant tumors with hair follicle differentiation (e.g., pilomatrix or trichoblastic

carcinomas)

  1. epitheloid sarcoma

Our experience indicates that although not all patients require a team approach and plastic surgery, preablation surgical consultation, including a thorough review of immediate and delayed reconstructive options and counseling regarding expected aesthetic outcomes, offers several advantages. Reaffirmation of the treatment plan by a second physician (plastic surgeon) enhances the sense of security by the patient and enhances the quality of the informed consent for a Mohs’ procedure. Of the sample, approximately ten per cent were first seen by a plastic surgeon and subsequently referred to a Mohs’ surgeon for ablative treatment. Typical clinical situations necessitating referral for Mohs’ surgery are listed in the table (table 2)(3,4).

Table 2.

Clinical scenarios and indications for Mohs’ surgery for malignancies of the head and neck.

  1. tumor located in sites that are reported to have relatively high rates of treatment failure

(e.g., periorbital, periauricular, and perinasal areas, nose)

  1. tumors with poorly delineated clinical border (e.g., the morphea-type of basal cell

carcinoma) or tumors arising from the scar tissue

  1. recurrent tumors
  2. large (> 2 cm) or deeply penetrating tumors
  3. perineural spread
  4. tumors located in areas where preservation of tissue or the highest chance of cure are

mandatory (e.g., eyelids)

  1. tumors with a propensity for local recurrence, but a limited potential for metastases (e.g.,

dermatofibrosarcoma protuberans)

Patient Management between the Mohs’ and Reconstructive Procedure

The majority of Mohs’ and subsequent repair procedures were done on an outpatient basis. The plastic surgeon is available for assistance should circumstances require such involvement during the ablation. Otherwise, the plastic surgeon is available to assess and repair the defect upon completion of the Mohs’ procedure. Ideally, the patient has already seen the plastic surgeon prior to the Mohs’ procedure and is familiar with reconstructive options. The majority of patients require similar medical work-ups for ablative and repair procedures. The extent of preoperative preparations is dictated by requirements related to the patient’s general health and age. Patients with preexisting medical problems require similar precautions as they would for other types of procedures using conscious sedation, local or general anesthesia.

The reconstructive procedures may be performed immediately or can be delayed. Tracing out the microscopic extensions of certain malignancies where there is a benefit of additional to frozen section stains (e.g., immunostains for melanoma) or permanent sections (e.g., for dermatofibrosarcoma protuberans), may require an intermediate surgical step such as wound temporization until histological results are known prior to the reconstructive procedure (figure 1)(3). Patients with chronic lymphocytic leukemia are at heightened risk for the development of cutaneous malignancies, especially squamous cell carcinoma, which are frequently multiple and locally aggressive. In addition, leukemic infiltrates in lymphoma-associated squamous cell carcinoma present a procedural challenge during Mohs’ surgery at which time cytokeratin-stain may be added to help to distinguish leukemic infiltrates from perineoplastic inflammation and to identify keratinocyte antigens, warranting planning of delayed reconstructions (6).

Figure 1. A 60-year old female with dermatofibrosarcoma protuberans of the forehead who required a series of three excisions because permanent sections indicated positive deep or radial margins. Skin allograft or like in this case coverage with a temporary alloplastic material (Biobrane, Dow B. Hickam, Sugar Land, TX) allow wound protection from desiccation, microbial contamination, permits fluid drainage, reduces pain and bridging to the time when the defect could be repaired. Biobrane transparency allows for easy wound evaluation.

Reconstruction after Mohs’ Ablative Surgery

Once tumor-free margins are confirmed the defect is ready for closure. The simplest and easiest form of treatment is to allow the defect to heal by contraction and epithelialization. This option is particularly well suited for small, circular defects in non-contour-critical areas. However, even a few millimeters of distortion in the helical rim of the ear, eyelid, retraction by contracting scar and subsequently notching of the nasal rim or vermilion, can create aesthetic problems. Similarly, a simple, linear closure of fusiform defects in these areas frequently results in a deformity. An unfavorable aesthetic outcome can be predicted by pulling the wound edges together using single skin hooks, and thus mimicking the area contour after wound healing by contraction. If a contour distortion becomes obvious during such a maneuver, then it is likely the same will occur if the wound is allowed to heal by secondary intention. In such a situation, it is wise to repair the defect by replacing the missing tissue. This can be accomplished by the undermining and stretching of neighboring skin, or through skin grafts or flaps, brought to the defect. Even if simple closure of an oval defect is possible, “dog ear” deformities frequently develop and correction may require adjunctive incision(s) with unacceptable lengthening of the wound. Therefore, on occasion, it seems advantageous to allow the small wound to contract and heal, or to apply a thin split-thickness skin graft (also expected to contract thus diminishing the size of the final mark). A small stellate scar, or contracted skin graft, can be re-excised later converting the ultimate defect to a small, inconspicuous, easy to camouflage by make-up scar. In situations where tissue laxity permits, re-excision of the post-Mohs’ defect and even a primary closure may give superior results to complex reconstruction (figures 2 and 3).          

Figure 2. Left: basal cell carcinoma of the lower lip. Right: lip defect resulting from basal cell carcinoma removal by micrographic surgery technique.

Figure 3. Top: lip wound was excised, converted to a vertical defect, and closed primarily. Bottom: result a few months after repair.

 

Most repairs can be accomplished using standard plastic surgical techniques. Small oval defects can be repaired with thick partial-thickness or full-thickness skin grafts (figure 4). Skin grafts harvested from the pre- or retroauricular area or even nasolabial fold area in older patients offer superior color and texture matches to grafts from the trunk or extremities. To avoid a step deformity in repairing defects of the nasal tip area, which is surrounded by relatively thick skin rich in sebaceous glands, one should carefully select the tissue used for repair. Skin from the preauricular area seems to be thicker than retroauricular skin and gives a good color match in the repair of nasal tip defects. Nasolabial skin is often thick and also similar in texture to nasal skin. They are good choices for patients with relatively smooth skin and who would very likely have a sight scar if a local skin flap was used (figure 5).  Conversely, a local skin flap is an excellent choice for the repair of skin defects with natural irregularities of the skin surface (e.g., sun-damaged skin, wrinkles, etc.) (figures 6 and 7). In such cases, both skin flaps and the flap donor site scar blend with the surrounding tissue and become inconspicuous, especially if suture lines are placed in natural creases.

Figure 4. Left: small defect in the medial canthal area from the Mohs’ excision of a basal cell carcinoma. Right: result with full-thickness skin graft after 12 months.

Figure 5. Top: patient with a relatively smooth skin, nasal tip defect following excision of basal cell carcinoma. Bottom: result with full-thickness preauricular skin graft after 6 months. The somewhat “shiny” surface can be camouflaged with make-up. A male and older patient with more surface skin irregularities causing that skin graft would not blend with surroundings and would be more difficult to camouflage, would be probably treated with a skin flap.

Figure 6. Top: forehead defect after basal cell carcinoma removal. Bottom: result 6 weeks after repair using double-rhomboid skin flap

Figure 7. The same patient shown in photograph 6 four years after surgery. Scar blended very well with the surrounding skin.

Composite and three-dimensional defects may require a more technically complex, and possibly staged, repair. A full thickness nose defect is a common example of a defect requiring the replacement of lining, support structures and cover, as well as restitution of contour (figure 8). Composite auricular grafts (skin and cartilage) may be useful for the repair of small alar rim or certain lower lid defects.

Figure 8. Left: full-thickness left nasal alae defect after excision of basal cell carcinoma. Middle: rotational skin flap from the center of the nose was skin grafted (thin split-thickness) to provide lining of the flap on the vestibular side, split-thickness skin graft was used to repair the flap donor site. Right: one year after reconstruction, the patient declined a Z-plasty to improve the definition of the groove between his nose and cheek.

Staged repair with tissue expansion is a possible reconstructive option for larger two-dimensional skin defects. Younger patients with relatively taut skin may benefit from an intraoperative tissue expansion even for reconstruction of relatively limited in size defects.

For patients with a question of local bone invasion, patients with malignancies posing a high risk of recurrence, and those who demonstrated a carcinogenic field effect, it is wise to delay definitive reconstruction (3,7). In such circumstances, additional margins excision and wound closure or coverage by simple means, without obstructing the capability to detect early tumor recurrence, is preferred. Immediate defect repair in such cases by a tissue flap may be disastrous from the standpoint of recurrence of cancer hiding beneath a thick flap and precluding early detection and intervention (figure 9). These types of patients are good candidates for external permanent or temporary prostheses (figure 10). If definitive autologous tissue reconstruction is undertaken, it is usually performed after 1 to 2 years of tumor-free follow up (3).

Figure 9. Very early recurrence of squamous cell carcinoma and mucosal adenocarcinoma under the flap used to reconstruct the nose.

Figure 10. Left: a patient with multiple recurrences of basal cell carcinoma uses a partial nose prosthesis. This prosthesis is completely self retained, inconspicuous, removable (for daily cleaning), and functional permitting normal  breathing and vocal resonance. Right: after prosthesis removal, examination for recurrent lesion is easy.

Mohs’s vs Wide Local Excision

Wide local excision with precise margin control is a surgical option. All margins must be free of tumor prior to repairing the defect. For example small (< 2 cm in diameter), well differentiated squamous cell carcinoma lesions can be adequately excised with a 4 mm margin, and larger tumors should be excised with 10 mm margins (8,9,10,11). However, it is striking that Mohs’s surgery provides high cure rates similar to those resulting from the so-called wide surgical excisions (>90% range for most cancers) (3,10). It is possible that both approaches suffer from different limitations: even wide surgical excision (without histological scrutiny of all margins) may be more likely than Mohs’ surgery to leave foci of positive margins (minimally residual cancer), while the latter does not provide margins wide enough to eradicate the carcinogenic field. Therefore, paradoxically, local recurrence (tumors with the same genetic pattern as the primary lesion) are more likely to occur in cases when the original lesion was treated by wide excision, while the second field tumor or second primary tumor (genetically different) may more likely affect patients originally treated by micrographic surgery (7,12,13).

In conclusion, it is worthwhile to reemphasize that the team approach and cross-specialty familiarity with the technical details of Mohs’ surgery and approaches to reconstruction is not only reassuring for the patient, but may be helpful in the “interpretation” of unusual findings and problem-prevention or solving (3,8,9).

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