BASAL CELL CARCINOMA SUBTYPES

Underreporting of basal cell carcinoma (BCC) subtypes occurs in academic, teaching and nonteaching institutions and may place patients at risk for inadequate or inappropriate therapy, researchers say.

"In our Mohs micrographic surgery practice for skin cancer, we began...noticing that when BCCs were referred without a histologic subtype reported on the biopsy pathology form, there were often unintended consequences," Drs. Ashley Wysong and Dr. Adam Sutton of the University of Nebraska Medical Center in Omaha told Reuters Health by email. "We decided to look at this in a more systematic way."

"Our analysis found that the practice setting was the most significant factor determining whether or not a BCC was subtyped," they said by email. "Specifically, in an academic or teaching institution, the subtypes were reported 93% of the time compared to 64% of the time in non-teaching institutions or private practices. The underreporting of subtypes also happened more often on high-risk areas of the body, including the head and neck."

As reported online April 17 in JAMA Dermatology, Drs. Wysong, Sutton and colleagues studied 928 BCCs treated with Mohs micrographic surgery by Dr. Wysong from 2015 through 2017 and found that BCC subtypes were not specified in 94 (10.1%) of biopsy pathology reports.

Lack of subtype reporting did not vary by patients' race/ethnicity or insurance but was significantly associated with the practice setting, as Dr. Wysong noted. The subtype was missing from 6.2% of reports from academic institutions, 23.7% from other teaching institutions (i.e., supporting graduate medical education), and 36.2% from nonteaching institutions.

Overall, BCCs without subtypes required a significantly higher number of Mohs layers to achieve clearance, and 44.7% had aggressive subtypes identified on Mohs excision, including infiltrating (23.4%), micronodular (22.3%), morpheaform (4.3%), and basosquamous (2.1%). Four of these cases showed invasion beyond the subcutaneous layer, including one that had perineural invasion.

A comparison of BCCs lacking subtypes with BCCs classified as nonaggressive on the biopsy report found that intraoperative detection of unsuspected aggressive subtypes was significantly more frequent in BCCs lacking subtypes on the initial biopsy report (odds ratio, 1.92). Some pathology reports stated that subtypes could not be given due to limited tissue availability, as may occur in small biopsies, but most reports did not provide explanations.

The findings suggest that "BCCs should not be assumed to be nonaggressive if no subtype is provided," the authors state.

"We believe these findings are important as they highlight a potential practice gap in the management of basal cell carcinoma," said Drs. Wysong and Sutton. "Appropriate subtyping of BCCs is necessary to guide treatment recommendations and patient counseling."

Dr. Anna Pavlick, Co-Director, Melanoma Program at NYU Langone's Perlmutter Cancer Center in New York City, commented, "Although the numbers are small, this information provides meaningful insight for clinicians and pathologists."

"Use and acceptance of descriptive terms to better classify BCCs as aggressive or non-aggressive will help guide surgical treatment plans, so that the best procedure to remove the lesion is used with the best possible outcome," she told Reuters Health by email. "This information may be most useful in elderly patients where very conservative measures are proposed due to other health issues."

"This highlights the need for standardization of dermatopathology reporting," she said. "By creating a standard dermatopathology reporting format that can be used worldwide, the standard of care for treating BCC will be raised and patients can receive optimal treatment based on these highly descriptive reports."