ORLANDO Reviewing the original biopsy slides of patients before they undergo Mohs surgery could result in a change of diagnosis, which in some cases could avert unnecessary surgery, according to Dr. Suzy T. Butler.
In a retrospective study of 3,345 patients, a second review of the original biopsy slide resulted in 74 changed diagnoses. Of these, 45 patients had a change in their management and 25 avoided an unnecessary surgery, Dr. Butler said at the annual meeting of the American Society for Dermatologic Surgery. The study reviewed all patients referred to the cutaneous oncology unit for Mohs surgery at St. Louis University from January 2003 to March 2007.
In one case, a 76-year-old white female presented to her dermatologist with a pink papule on her right cheek that had been previously treated with liquid nitrogen. A shaved biopsy showed an atypical spindle cell proliferation that was read as a desmoplastic malignant melanoma.
A review of the biopsy slides, however, diagnosed the patient as having dermal scar, said Dr. Butler of St. Louis University. Because of this discrepancy, additional biopsies were performed. These confirmed the diagnosis of scar. An s100 stain showed a few spindle cells in the dermis. Surgery was cancelled, and close observation was planned.
In another case, a 74-year-old white male presented with a 1-year history of pink scaly plaques at the suprapubic area. A punch biopsy was originally read as superficial spreading melanoma in situ.
A review of the biopsy before surgery, however, suggested extramammary Paget disease, which was confirmed with additional biopsies. The patient underwent "slow Mohs" surgery with permanent section histology, as well as a thorough malignancy work-up that was negative.
"These cases illustrate how second-opinion review of histopathology before treatment can either avoid potentially disfiguring, unnecessary surgery or direct a different surgical approach and guide the need for other testing," said Dr. Butler.
In addition to recording the number of cases in which the diagnosis changed, the investigators noted how the diagnosis changed and then reviewed the patient's chart to see how that change affected the patient's management. They also recorded the board certification of the original pathologist. Nearly half (48%) of the slides that were rediagnosed had been read by certified dermatopathologists, Dr. Butler said.
The most common change in diagnosis was from one malignant tumor to another in 43% of the patients. Most commonly, a basal cell carcinoma (BCC) diagnosis changed to squamous cell carcinoma (SCC), or a melanoma went from in situ to invasive or vice versa, Dr. Butler said.
The next most common change in diagnosis was from malignant to benign in 36% of the patients. This was often a seborrheic keratosis or a verruca vulgaris being misdiagnosed as SCC.
BCC was most likely to be misdiagnosed, followed by SCC, and then by melanoma and melanoma in situ, Dr. Butler noted. Seventeen percent of discordant diagnoses involved melanoma and melanoma in situ.
"Misdiagnoses involving basal cells are likely related to their high representation in our population, as opposed to any diagnostic challenge," she said. "On the flip side, considering the small proportion of total tumors that melanoma and melanomas in situ represent in our population, they comprise a surprisingly substantial proportion of the misdiagnosed tumors."
She suggested that the diagnoses of melanoma or melanoma in situ might be the most cost-effective diseases to target with second-opinion review.
The most common change in patient management was cancellation of surgery in 25 patients. The planned surgical approach was changed in another 10 patients, and 1 patient had to be scheduled for surgery as a result of the second biopsy reading, Dr. Butler said.
The cost of taking a second look at biopsy slides is considerable, however. "We did a cost analysis and found that the estimated cost of reviewing the biopsy slides would be approximately $93,000 a year at our university based on the number of slides we look at per year. That is significant, but it has to be weighed against the other benefits," she said.
Surgeons gain much useful information regarding the nature of the tumor, particularly useful when there are deeply infiltrating, aggressive tumors or in cases of perineural involvement, said Dr. Butler, who disclosed having no conflicts of interest relevant to her presentation.
Melanoma and melanoma in situ might be the most cost-effective diseases to target with second-opinion review. DR. BUTLER