Fresh Tissue Technique

M.P. McLeod • K. França

Department of Dermatology and Cutaneous Surgery, University of Miami Leonard M. Miller School of Medicine, Miami, FL, USA

K. Nouri (*)

Department of Dermatology and Cutaneous Surgery,

University of Miami Leonard M. Miller School of Medicine,

Miami, FL, USA

Sylvester Comprehensive Cancer Center, University of Miami Hospital and Clinics, Miami, FL, USA

e-mail: knouri@med.miami.edu

Summary: Introduction

•The fresh tissue technique was initially used for eyelid cancers.

•The modern approach to Mohs micrographic surgery predominantly involves the fresh tissue technique.

•Histologic preparation for microscopic examination in Mohs surgery requires skill and practice.

•Several other techniques have been described for rapidly freezing tissue and enhancing histology, including isopentane histopath, liquid nitrogen, and dry ice.

Mohs Micrographic Surgery originally used fixed tissue sections. It was not until 1953, during the filming of Dr. Mohs removing a pigmented BCC from the patient’s lower eyelid that the fresh tissue technique became known. In order to prevent a delay in filming the procedure, Dr. Mohs sped along the process by carrying out the last two stages using fresh frozen tissue. From that time forward Dr. Mohs used the fresh tissue technique for nearly all eyelid cancers. That way the zinc chloride paste did not risk coming into contact with the patient’s eyes. However, at the time, serious doubts were raised as to whether the fresh tissue technique would be as effective as the fixed tissue technique.

In 1956, the first written material documented the fresh tissue technique in Dr. Epstein’s text book, Skin Surgery. The turning point came in 1969, at the annual meeting of the American College of Chemosurgery. It was at this time that Dr. Mohs reported 100%, 5 year cure rates using the fresh tissue technique for 66 basal and squamous cell carcinomas. The following year in 1970, Dr. Tromovitch presented an additional 75 patients with the fresh tissue technique with excellent results. In 1974, Tromovitch and Stegman presented a 99% cure rate from 102 patients. The fresh tissue technique finally became accepted when Dr. Mohs reported his 5 year cure rate of 99.8% cure rate with 3,466 patients [1]. The fresh tissue technique is now well accepted and has become the predominant technique for Mohs Micrographic Surgery [2].

Summary: The Technique

•It is important to confirm the exact site of the previous biopsy and outline the tumor with a marking pen.

•After the anesthetic process, a curette should be used to debulk the tumor

•It is important to maintain specimen orientation

•The tissue should be excised with the scalpel angle 45° to the skin to facilitate the histological process and the deep margin should be excised horizontally

Before starting the surgery, it is important to confirm the exact site of the previous biopsy and outline the tumor with a marking pen. This should be done prior to injecting the local anesthesia, because it can distort the original anatomic landmarks of the tumor.

After waiting some minutes for optimal local anesthetic effects, a curette should be used to debulk the tumor, to better delineate its extension.

The precise orientation of the specimen is important to maintain and can be carried out by making superficial scalpel incisions at the periphery of the specimen or using a substance such as methylene blue, sutures, staples, or hatch marks.

The tissue should be excised with the scalpel angle 45° to the skin to facilitate histological processing and the deep margin should be excised horizontally. The hemostasis process is achieved by using pressure, electrocautery or suture ligatures if necessary.

It is important to draw a 2-dimensional map of the tumor with markers used to orient the specimen. This map is used in orienting the specimen as well as guiding the surgeon to remove any residual neoplasm.

Summary: Histologic Preparation of the Tissue

•After excision, the tissue is carefully processed in a special lab by the technician.

•The technician must mount the tissue as it is presented, flattening it’s surface in an even horizontal plane. Then, it must be cut as frozen sections, using a cryostat.

•The slides are usually stained with hematoxylineosin and are ready for interpretation by the Mohs surgeon.

8.3Histologic Preparation of the Tissue

Histologic preparation for microscopic examination in Mohs surgery requires skill and practice.

After the excision, the tissue is carefully processed in a special lab by the technician.

The specimen is usually divided along the marked lines and inverted, so the dermis faces upwards. The edges of the tissue are then color-coded with tissue dyes.

The technician must mount the tissue as it is presented, flattening it’s surface in an even horizontal plane. Then, it must be cut as frozen sections, using a cryostat. The horizontal sections are taken at 5–7 mm. Several other techniques have been described for rapidly freezing tissue and enhancing histology, including isopentane histopath, liquid nitrogen, and dry ice [3–5].

The epidermal margin and the entire surface of the excised specimen is thoroughly processed. Each saucerized piece of tissue is compressed and it is horizontally sectioned from the deep margin upward. The slides are usually stained with hematoxylin-eosin, and are ready for interpretation by the Mohs surgeon.

Summary: Conclusion

•The Fresh tissue technique is less painful, faster and conserves more tissue when compared with the fixed technique.

•This technique allows for immediate reconstruction.

8.4Conclusion

The modern approach to Mohs micrographic surgery predominantly involves the fresh tissue technique. The original fixed tissue technique did not allow for immediate reconstruction. Sometimes 6-8 weeks were required for complete granulations to heal the defect when the fixed tissue technique was used. The use of the fresh tissue technique allows immediate reconstruction. It is also less painful, quicker and conserves more tissue when compared with the fixed tissue technique [2].

References

1. Mohs FE. The chemosurgical method for the microscopically controlled excision of cutaneous cancer. In: Epstein E, editor. Skin surgery. Philadelphia: Lea & Febiger; 1956.

2. Lang PG et al. Mohs micrographic surgery. Fresh-tissue technique. Dermatol Clin. 1989;7(4):613–26.

3. Erickson QL et al. Flash freezing of Mohs micrographic surgery tissue can minimize freeze artifact and speed slide preparation. Dermatol Surg. 2011;37:503–9.

4. Cecchi R et al. Micrographic surgery (fresh-tissue Tübingen technique) for treatment of basal cell carcinoma of the head: a single-centre report. J Dermatol. 2008;35:678–9.

5. Bakhtar O et al. Tissue preparation for MOHS frozen sections: a comparison of three techniques. Virchows Arch. 2007;450:513–8.

Summary: Introduction

•Immune system compromise is theorized to play a critical role in accelerating the development of skin cancer in both organ transplant and HIV/AIDS patients. Chemotherapeutic agents may also promote carcinogenicity, and an understanding of these risk factors is essential for optimizing skin cancer management in this population.

T.Stasko (*)

Department of Medicine, Division of Dermatology, Vanderbilt University, Nashville, TN, USA

e-mail: tom.stasko@vanderbilt.edu

D.L. Christiansen

Department of Medicine, Division of Dermatology,

Vanderbilt Medical Center,

Nashville, TN, USA

9.1Introduction

Immunosuppressed patients present both diagnostic and therapeutic challenges for the Mohs surgeon. In the United States alone, there are over 183,000 living organ transplant recipients [1] and 1.1 million patients with HIV [2]. New drugs and therapies have provided patients with increased survival and enabled a growing epidemic of cutaneous disease. This subset of patients not only exhibit a much higher incidence of nonmelanoma skin cancer (NMSC) when compared to the general population but also tend to develop tumors that follow a more aggressive course, portending a poorer prognosis. While the exact contributions are unknown, the likely cause of this disparity is a combination of decreased immunosurveillance and a direct carcinogenic effect of certain immunosuppressant medications. With increased transplant organ survival and the need for ongoing immunosuppression, this incidence is likely to increase.