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Microcystic adnexal carcinoma guidelines encourage high-quality care

The Committee on Invasive Skin Tumor Evidence-Based Recommendations published clinical practice guidelines to improve clinical decision-making for patients with microcystic adnexal carcinoma based on a systematic review of the literature.

“The primary goal of the treatment of microcystic adnexal carcinoma is complete excision with clear surgical margins, while preserving function and cosmesis,” Brandon Worley, MD, MSc, of the division of dermatology at the Ottawa Hospital in Ontario, and colleagues wrote.

The information should not be viewed as a standard of care, but as recommended guidelines because individual cases may require varying management, according to researchers.

Overall, 55 studies with 1,968 patients met the inclusion criteria (mean age, 61.8 years; 54.1% women).

Microcystic adnexal carcinoma — or MAC — is marked by challenges, including local tumor control and recurrence, according to the researchers. Though consensus on diagnosis and management of this skin cancer is lacking, their findings led to the recommendation that biopsy of suspicious lesions include subcutaneous fat.

Next, they determined that Mohs micrographic surgery (MMS) or complete circumferential peripheral and deep margin assessment is associated with the highest chance of a cure and is recommended as first-line treatment.

“Alternatively, wide local excision with 2-cm margins with resection to the deep fascial plane may be considered in locations where this is feasible,” they wrote.

Due to limited evidence, the researchers do not recommend radiotherapy as first-line treatment, but primary radiotherapy may be considered for nonsurgical candidates. For those at high risk for recurrence, adjuvant radiotherapy may be used on an individual basis or for recurrent tumors, they wrote.

Assessing, diagnosing MAC

When MAC is suspected, the researchers recommend a complete physical examination, including a relevant neurologic and regional lymph node assessment.

“Complete physical examination is the most comprehensive and cost-effective manner to assess the extent of MAC,” they wrote.

When bony involvement is suspected, the panel recommends bone window CT, while gadolinium-enhanced MRI may be useful for suspected extensive perineural invasion, they wrote. To determine the severity of orbital invasion in extensive periocular invasion, the researchers recommend MRI with a fat-suppression protocol.

They noted data were unavailable regarding the link between imaging and improved survival or detection of occult nodal and metastatic disease. Additionally, due to a dearth of evidence, they were unable to recommend a specific frequency or type of imaging for patients with advanced or systemic disease.

To diagnose MAC, the experts recommend a punch or excisional biopsy to include subcutaneous fat due to numerous reports of extension into subcutaneous fat, muscle or bone.

MAC has a high rate of recurrence if peripheral and deep margins are not assessed and cleared, they wrote, “particularly if the uniform surgical margins obtained are 4 mm or less.”

When used in place of Moh’s micrographic surgery or complete circumferential peripheral and deep margin assessment, the researchers recommend that wide local excision include “2-cm peripheral margins with a minimum deep margin to fascia.”

A multidisciplinary care approach — including oculoplastic, plastic and head and neck surgery — is recommended in cases of severe infiltrative disease. “Tissue processing by a combination of frozen-section or permanent section peripheral margin en face sectioning and deep margin horizontal sectioning is recommended,” they wrote.

Use of multi-institutional registries

As for patient follow-up, they recommend discussing the following with patients: photoprotection, periodic self-examination, expectations regarding surgical scar and normal changes in sensation during healing.

Additionally, patients should be seen by a physician familiar with MAC every 6 to 12 months for the first 5 years after treatment.

The experts identified variability in the time to local recurrence, with some reported more than 10 years after treatment. Of recurrent MAC cases, 78.9% (15 of 19) recurred locally within 3 years after primary excision.

“Future efforts using multi-institutional registries may improve our understanding of the natural history of the disease in patients with [lymph node] or nerve involvement, the role of radiotherapy and the treatment of metastatic MAC with drug therapy,” they wrote. – by Abigail Sutton

Disclosures: Worley reports no relevant financial disclosures. Please see the study for all other authors’ financial disclosures.