Wide local excision, Mohs remain primary treatment options for positive tumor margins

Key takeaways:

• Positive margins are infrequent following standard excision, but when they do occur it is mostly in the upper extremities.
• In 59.1% of cases, wide local excision was the most commonly chosen treatment option.

ORLANDO — A speaker at the American Society for Dermatologic Surgery Annual Meeting discussed the treatment options for positive margins after standard excision of cutaneous melanoma.

“I think everyone knows that the standardized treatment for primary cutaneous melanoma is surgical excision,” Jennifer L. Strunck, MD, a third-year dermatology resident at Oregon Health & Science University, said during her presentation. “But what we do for positive margins is much less characterized.”

According to the presentation, the incidence of positive margins ranges from 0% to 6.3% with head and neck melanomas seeing incidence rates up to about 20%. Features associated with a higher risk for positive margins include older age; nodular, desmoplastic or spindle cell subtypes; advanced pathological tumor classification; and subsites of the lip, eyelid or face.

However, the data concerning how to treat positive margins are very limited, and Strunck discussed a study that aimed to fill that knowledge gap.

The study found that out of 67 patients that had undergone standardized excision for melanoma and received a histopathologic confirmed positive margins diagnosis, the majority had tumors removed from their upper extremities (43.2%), head and neck (19.4%) and trunk (19.4%). The least likely places for positive margins after melanoma excision were lower extremities (9%), genitals (1.5%) and acral sites (1.5%).

Most of the tumors were lower stage melanomas including in situ (61.2%) and T1a (23.9%).

Wide local excision (59.1%) was the most commonly used procedure to treat positive margin melanoma across tumor stage followed my Mohs micrographic surgery (22.7%) and observation (13.6%) which were exclusively utilized for early-stage tumors. Imiquimod was only used in .03% of cases, all of which were in situ.

Strunck and colleagues also observed that as the tumor grew, physicians often opted to observe rather than excise. Wide local excision and Mohs were also used across tumor location, whereas imiquimod was mainly used for head and neck tumors.

“Positive margins in our data set seem to be an infrequent occurrence following standardized excision,” Strunck said. “There are several treatments that have been utilized following these positive emergences, excision being far and away the most commonly used following Mohs, observation and imiquimod.”