Mohs’ Surgery New Concepts and Applications

Sebaceous carcinoma: an updated review of pathogenesis, diagnosis, and treatment options

Sebaceous carcinoma (SC) is a very rare and aggressive form of skin cancer that arises from the sebaceous glands. SC can occur anywhere on the body, but most commonly affects the head and neck, especially the upper eyelid. SC is the third most common malignancy of the eyelid and has the potential to metastasize and be fatal; therefore, it is vital for dermatologists to remain acquainted with this malignancy and its most current treatment options. Most commonly presenting as a painless lump or thickening of skin on the eyelid, SC has an insidious progression that may not prompt the patient to seek medical attention immediately. To avoid the potential of metastasis, early diagnosis and treatment is paramount. To assess if the cancer has spread, ophthalmology, imaging, and sentinel lymph node biopsy are recommended. This article provides a comprehensive review of SC's pathogenesis, current diagnostic methods, and treatments, including wide local excision, Mohs micrographic surgery, orbital exenteration, radiation, and other topicals. The prognosis of SC depends on several factors, including size, location, stage, and treatment method. After treatment of the neoplasm, diligent post-treatment surveillance remains the cornerstone of patient care. Continued dermatologic follow-ups are essential for early detection of reoccurrence, ensuring timely intervention and optimal long-term outcomes. In conclusion, this comprehensive review aims to equip dermatologists and other physicians with a nuanced understanding of SC, enabling them to provide effective care to support patients encountering this malignancy.

Options for the management of forehead and scalp defects

Forehead and scalp reconstruction comprises a diverse and complex set of defects. Repair must be performed with minimal disturbance to surrounding structures, such as the eyelid, eyebrow, and hairline. Care must be taken to maintain symmetry between sides. This article addresses the options for the management of forehead and scalp defects, including secondary intention healing, skin grafting, local flaps, free flaps, tissue expansion, and negative pressure treatment. When possible, special consideration is given to addressing the advantages and disadvantages of each repair option, while providing a framework from which to plan scalp and forehead reconstruction.

Reconstruction of scalp and forehead defects

Reconstruction of scalp and forehead defects is a complex field with a broad variety of reconstructive options. The thought process and techniques used for reconstruction of scalp and forehead defects are the subject of this article.

Scalp and Forehead Reconstruction

The reconstruction of defects that involve the scalp and forehead presents unique aesthetic and functional challenges. This article reviews the surgical anatomy of these regions and presents an algorithm for decision making in reconstructive surgery. Nonmicrosurgical techniques are briefly reviewed. The microsurgical reconstruction of scalp and forehead defects differs from the more common oropharyngeal reconstructions in several ways, including flap choices, choices for recipient vessels, and the opportunity to use conventional and microsurgical techniques simultaneously to improve outcomes. Each of these considerations is reviewed and the authors' preferred techniques presented.

Microscopically controlled excision of conjunctival squamous cell carcinoma

Although surgical excision, with or without adjunctive cryotherapy, is an accepted method of managing conjunctival squamous cell carcinoma, histologically verified tumor-free surgical margins cannot be assured by excision alone. We used a tissue conservation method, an adaptation of the Mohs' micrographic technique for cutaneous tumors, to monitor the conjunctival tissue margins by histologic review at initial tumor excision. We treated 19 patients with squamous cell carcinoma of the conjunctiva by this technique. Lamellar sclerectomy was used if the deep tissue margin was positive for residual tumor cell after the first stage review. Adjunctive cryotherapy was utilized in one patient because the deep scleral margin remained positive after lamellar sclerectomy, and further excision was not possible. In all patients, the tumor-free conjunctival defect was allowed to heal by secondary intention. During six months to 60 months of follow-up, no recurrences were documented. The only complication encountered was conjunctival scarring with secondary restricted motility in one patient. We believe this method of tissue margin surveillance offers a high cure rate for the treatment of conjunctival squamous cell carcinoma.

Mohs micrographic surgery of the nail unit

Malignancies of the nail unit are relatively uncommon, with squamous cell carcinoma (SCC) representing most of the reported cases. Squamous cell carcinoma of the nail unit, although commonly considered to be a curable malignancy, can and does kill. Review of the literature as well as a personal series confirm that Mohs micrographic surgery is an ideal treatment for periungual and subungual SCCs without osseous involvement. In addition, the anatomy and histology of nail unit SCC, as well as prognostic factors and perioperative evaluation as they relate to performing Mohs micrographic surgery, are reviewed.

Pitfalls of Mohs micrographic surgery

This article discusses some of the pitfalls and disadvantages of Mohs micrographic surgery for the excision of skin cancer. These include (1) frozen section quality; (2) interpretation of frozen sections; (3) holes in fragmented tissue margins; (4) tissue orientation problems; (5) excessively narrow or wide margins; (6) transection of the tumor itself; (7) problems with multifocal tumor; and (8) the tedious, time-consuming nature of the procedure. Despite these problems, the importance of the procedure in the treatment of cutaneous neoplasms should not be underestimated.

Interpretation of Mohs micrographic frozen sections: a peer review comparison study

The ability of the Mohs surgeon to interpret frozen sections generated during Mohs surgery has been questioned recently. In this study 1000 Mohs micrographic slides were interpreted by a Mohs surgeon and subsequently by a general pathologist. The disputed slides were then reviewed independently by two Mohs surgeons, two pathologists, and a dermatopathologist. Overall, there was a 98.9% agreement in interpretation among the Mohs surgeons, the pathologists, and the dermatopathologist. Results would indicate that a well-trained and experienced Mohs surgeon is competent to interpret slides prepared under his or her supervision during Mohs surgery.

Cryotherapy for conjunctival primary acquired melanosis and malignant melanoma. Experience with 62 cases

Sixty-two patients were treated by some combination of cryotherapy and surgery with an average follow-up of 3.3 years for one of the following diseases: focal or diffuse flat conjunctival primary acquired melanosis (PAM) with atypia but without a nodule of melanoma (10 cases); unifocal malignant melanoma with or without focal or diffuse PAM (30 cases); and multinodular/multicentric melanoma with and without PAM (22 cases). Of the ten patients who had PAM with atypia, invasive nodules of malignant melanoma did not develop. A second treatment was required to control the disease in four of the ten patients with extensive or diffuse lesions, and one has mild persistent disease. Of the 30 patients with unifocal nodules of malignant melanoma, 27 remained free of recurrence after one treatment, and 2 are asymptomatic after two treatments. One patient with a thick nodule at presentation required a parotidectomy and radical neck dissection for cervical metastases after recurrence in the conjunctival sac. In the group of 22 patients with multinodular malignant melanoma, only two did not have recurrent disease after one treatment. Of those who received multiple therapies, seven remained free of recurrence for at least 2 years after the last treatment; regional or distant metastases developed in nine; four required exenteration; and eight died. Conjunctival adjunctive cryotherapy avoids exenteration in extensive lesions of pure PAM and in unifocal melanoma, but even after multiple therapies, multinodular malignant melanoma had a 45% rate of metastasis. Metastasis was related to the presence of PAM sine pigmento in four patients (microscopically but not clinically detectable PAM); to the location of the nodules (9 of 10 patients who experienced metastases had forniceal, palpebral, and/or caruncular nodules); to the thickness or depth of invasion of the nodules (greater than 2 mm); and to the development of intralymphatic spread ("in-transit" local metastasis) within the conjunctival sac in six patients. No metastases were encountered among patients with strictly limbal nodules and among five patients with invasive nodules composed of spindle cells in part or in toto. Therapeutic success in this spectrum of melanocytic proliferations is closely correlated with the clinical extent of the disease when initiating definitive therapy.