Genitalia

Summary: Introduction

•Major advantages of Mohs micrographic surgery (MMS) in management of mucocutaneous neoplasms of the male and female external genitalia include:

–MMS allowing for margin control, which enables complete removal of the tumor and subsequently leads to reduced recurrence rates in the treatment of a variety of neoplasms

I.Vergilis-Kalner

Assistant Professor of Dermatology, Department of

Dermatology, UMDNJ, New Jersey

A. Kimyai-Asadi (*) DermSurgery Associates, Houston, TX, USA

e-mail: akimyai@yahoo.com

29.1 Introduction

The advantages of total microscopic control of excision margins that are provided by Mohs micrographic surgery (MMS) often justify consideration of this modality in the management of neoplasms of the male and female external genitalia. MMS has three major advantages in the management of mucocutaneous neoplasms of the genital region. First, MMS has been shown to reduce recurrence rates in the treatment of a variety of cutaneous neoplasms. The excision in successive layers with complete microscopic examination of the entire surgical margin of each excisional specimen assures eradication of any subclinical outgrowths that may extend beyond the clinically visible and palpable borders of a cancer, thereby reducing postsurgical recurrences.

Second, MMS reduces the amount of normal tissue that is removed around a tumor. Upon histologically confirmed elimination of the entire tumor, the excisions are ceased, and the surgical removal of a potentially significant additional margin of normal tissue is obviated. Thus, significantly reduced recurrence rates do not come at the expense of unnecessary removal of additional tissue around a tumor site as is typically the case in surgical oncology. As such, MMS allows for maximal conservation of normal tissue in critical anatomic structures such as the genitalia, while yielding higher cure rates than other conventional methods of treatment.

Third, with complete histologic control of the surgical margins, the surgeon can be confident that the tumor is no longer present, and therefore feels free to pick the optimal reconstructive method without particular concern regarding tumor recurrence and without the need to delay reconstruction or alter reconstructive choices while awaiting delayed histopathology results or while monitoring the local area for tumor recurrence.

Further advantages of MMS include the absence of need for general anesthesia, the fact that surgery is performed on an outpatient basis, and the fact that patients remain ambulatory. As such, Mohs micrographic surgery should be considered the technique of choice in the management of most cutaneous malignancies of the genital region.

Summary: Surgical Technique

•Steps during Mohs micrographic surgery (MMS):

–Clinical margins of the tumor are evaluated and marked with a surgical pen.

–The patient is asked to verify the location of the tumor.

–Local anesthesia is obtained with an injection of lidocaine mixed with epinephrine and buffered with sodium bicarbonate to reduce injection site pain.

–Bulky tumors may be curetted prior to taking the first stage to debulk the tumor and to delineate possible subclinical tumor spread.

–The first stage is removed, and subsequently, the tissue is mapped.

29.2Surgical Technique

The effectiveness of the Mohs technique is dependent on the individual steps that constitute the surgical procedure. These steps include preoperative physical examination, skin tumor extirpation, tissue mapping, histologic processing, and microscopic examination. The procedure is repeated until histologically clear margins are obtained. The postoperative defect is subsequently repaired by an optimal reconstructive technique.

When initially examining a patient, the clinical margins of the tumor are evaluated and marked with a surgical marking pen (Fig. 29.1a). The patient is then asked to verify the location of the tumor with a mirror, and the patient’s identity is again confirmed. Local anesthesia is obtained with an injection of lidocaine mixed with epinephrine buffered with sodium bicarbonate. A curette may be used prior to excision to debulk and delineate possible subclinical tumor spread, although the utility of preoperative curettage is debatable and may result in larger surgical defects. Furthermore, the loose tissue of the penile shaft and prepuce, scrotum, and female genitalia are not easily amenable to preoperative curettage, making this modality best reserved for bulky genital tumors requiring preoperative debulking.

Classical MMS advocates that the blade be beveled at a 45° angle to the skin surface when excising the tumor margin. This allows the epidermis, dermis, and deeper tissue to be cut on the cryostat in a straight line and to be examined in one plane. However, this does not guarantee a complete epidermal edge for histologic evaluation in every case due to difficulties in tissue flattening and sectioning sections composed of epidermis, dermis, and fat. A more complete epidermal and dermal edge may be obtained by using a peripheral 90° vertical incision all around a neoplasm and separately examining horizontal sections from the tumor’s base to evaluate the deep margin and vertical sections from the tumor’s periphery to evaluate the peripheral margin (Fig. 29.1b). The 90° removal approach may also speed up the procedure by obviating the need for incising the margins vertically at 90° and excising the beveled edge to facilitate subsequent closure.

After tumor excision, the excised tissue must be accurately mapped and marked with ink for proper orientation. Despite a unified concept of margin control for tumor extraction, there are several variations in each step of this technique. Most Mohs micrographic

Fig. 29.1 (a) Bowen’s disease of the vulva; image depicts clinical margins of the tumor being evaluated and marked with a surgical marking pen in preparation for taking an MMS layer. (b) MMS surgery layer demonstrated next to its respective

defect. (c) MMS surgery layer taken after the previous stage has shown involvement of the lateral margin. (d) Reconstruction of the surgical defect following removal of skin cancer with MMS

surgeons map their tissue using hand-drawn sketches to orient the specimens. This method is inexpensive, simple, and quick and gives the surgeon artistic freedom to illustrate the size and shape of removed neoplastic tissue and the surgical defect. Some Mohs micrographic surgeons use preprinted maps or sketches of anatomic sites. It is as simple and rapid as drawing a picture by hand, except that the size and shape of the anatomic regions are fixed. Digital and Polaroid photographs produce the most accurate representations of the excised tissue, defects, and their interrelationship. They may also provide dimensions and archival information for follow-up. Currently, this approach is used by a minority of Mohs surgeons, but it may increase with the more widespread use of digital photography and electronic medical records.

Preparing tissue specimens for processing involves inking, flattening, freezing, sectioning, and staining, followed by microscopic examination. The Mohs histotechnologist plays a crucial role in this process and must consistently orient the tissue so that the correct surface is sectioned. Mohs surgeons should be familiar with the processes of flattening, freezing, sectioning, and staining tissue in order to efficiently communicate and troubleshoot quality issues with their histotechnologists.

Flattening the tissue in order to section the complete undersurface and the epidermal margin is critical for the complete en face examination of the outer margin of a tissue specimen. Heat-extractor flattening in the cryostat with or without preceding relaxing tissue cuts or slits is the most common method used for tissue flattening. Relaxing cuts are particularly useful when

thick specimens are obtained for processing or when the tissue is inelastic. Aerosol or liquid nitrogen freezing on a glass slide, plastic or metal plate, or X-ray film is another technique commonly used to flatten tissue. More than one method is frequently utilized depending on the particular specimen.

The flattened tissue is then embedded in optimal cutting temperature compound so that the specimen may be sectioned and slides may be prepared for histologic evaluation. Thinner sections are necessary for proper evaluation of epithelial involvement. As such, epidermal and dermal specimens should be sectioned at 4–6 mm, whereas fatty subcutaneous tissue may be sectioned at a thickness of 15–25 mm. Sections that are too thick are difficult to evaluate and can lead to inaccurate interpretation. While thinner sections enhance cellular detail, they require more deeply frozen specimens. Furthermore, fatty tissue tends to fray when the sections are very thin. Obtaining several serial sections of each tissue specimen allows one to further differentiate normal adnexal structures or artifact from tumor nests. Although more processing time is required for serial sections, it may reduce the number of erroneous or equivocal interpretations of the surgical margins.

Subsequent to sectioning, the tissue slides are stained. Hematoxylin-eosin is the most commonly used tissue stains in MMS, and it can be used for all cutaneous neoplasms including squamous cell carcinoma, basal cell carcinoma, and malignant melanoma. Toluidine blue is an alternative stain that is particularly useful when evaluating basal cell carcinoma and is preferred by some Mohs surgeons. Toluidine blue highlights islands of basal cell carcinoma by metachromatically staining the mucopolysaccharides surrounding tumor nests a vibrant purple-pink color. The use of both toluidine blue and hematoxylin-eosin for different sections of the same specimen has occasionally been advocated when the histologic assessment of a tumor is not straightforward. For malignant melanoma, the concomitant use of MART-1 immunostains with hematoxylin-eosin stained sections may improve the sensitivity and specificity of detection of melanoma in frozen sections performed from the surgical margins.

The surgeon then evaluates the slides to determine if the surgical margins are involved with tumor. One of the major advantages of MMS is its potential to allow the surgeon maximal conservation of normal tissue. If tumor is present in the surgical margins, the corresponding location is marked on the Mohs map.

Similarly, the presence of dense inflammation, fibrosis, or stromal changes at the margins may require additional excision to ensure that the margins are truly free of tumor. If the lateral margin is involved, an additional excision of 1–2 mm of tissue is performed (Fig. 29.1c). If tumor is present in the deep margin, an incision is made along the inside of the defect’s edge, and a thin strip of tissue is removed from the depth of the defect for additional histologic evaluation. These stages are repeated until the margins are found to be histologically clear, and reconstruction, when required, is then performed. Once the histologically examined margins are free of tumor, the surgical defect is reconstructed regardless of how narrow the surgical margins utilized were (Fig. 29.1d).

Summary: Reconstruction

•Most Mohs micrographic surgery (MMS) defects on the genitalia can be repaired with primary linear closure

29.3Reconstruction

Most lesions on the penile shaft, female genitalia, and scrotum can be repaired with a primary linear closure. On the glans penis, which is a richly vascularized area, skin grafts allow for preservation of structure and function and are a great option for reconstruction of most defects. If the urethral meatus is involved, the insertion of a Foley catheter may be necessary to reduce the risk of meatal stenosis.

In general, if the surgical defect is extensive and cannot be closed with a primary linear closure, a variety of advancement, rotation, and transposition flaps, as well as skin grafts, may be used to reconstruct such defects. When there is no available skin for closure, penile burial with subsequent surgical release in the scrotum or in the suprapubic region may be performed. Posterior scrotal skin may be used for primary closure of the scrotum, as posterior scrotal skin can usually be stretched to cover most scrotal defects. Moreover, any subsequent defect from the expansion of the posterior scrotal skin to cover the injured area can be grafted. Other reconstruction techniques include abdominal pedicled fascial flaps and paraumbilical island flaps. Furthermore, genital skin has frequently been reconstructed