Immunohistochemistry utilization in the diagnosis of melanoma.

BACKGROUND: The use of immunohistochemical (IHC) stains in dermatopathology is commonplace; however, little is known regarding utilization trends in melanoma diagnosis. Current Medicare local coverage determinations (LCDs) state that most pigmented lesions, including melanoma, can be diagnosed using H&E alone. METHODS: Histopathology reports for all biopsy-proven melanomas excised between January 1, 2017 and June 30, 2018, at a single dermatology clinic, were identified with the following parameters abstracted: laboratory/dermatopathologist rendering the diagnosis, whether IHC was performed, type/number of stains utilized, presence/depth of invasion, and melanoma subtype. The association of characteristics with IHC utilization was evaluated using χ2 test for categorical variables. RESULTS: Three hundred and fifty six eligible melanomas were identified. IHC was employed in 228 (64%) of the diagnoses. Invasive melanoma was diagnosed in 199 cases (55.9%) while 157 (44.1%) were identified as melanoma in situ (MIS). Of the 228 that utilized IHC, 117 were performed on invasive melanoma (58.8%) and 111 were performed on MIS (70.7%). CONCLUSION: Our findings suggest a higher IHC usage for the diagnosis of melanoma than previously reported. Existing LCDs regarding IHC utilization in melanoma do not reflect the current state of practice. Further investigation regarding IHC utilization and the development of appropriate-use criteria for melanoma IHC is necessary.

Colliding, colonizing or combining? Four cases illustrating the unique challenges presented by melanoma arising in conjunction with basal cell carcinoma.

Biphasic lesions comprised of melanocytic and epithelial components are rare entities believed to arise either as a collision of 2 histologically distinct lesions in the same anatomic location or as a singular progenitor tumor differentiating along 2 differing lineages. Regardless of mechanism of origin, these tumors present unique challenges in pathologic interpretation and in determining appropriate measurements, which assigns subsequent prognosis to the patient. We present 4 tumors of melanoma co-existing with basal cell carcinoma (BCC) and discuss relevant literature regarding these biphasic entities. Patients consisted of 3 males and 1 female, ranging in age from 62 to 93, with lesions located on the shoulder, frontal scalp, forearm and nose. Three of 4 lesions showed melanoma cells limited to BCC tumor lobules, without evidence of direct dermal invasion by melanoma cells, raising the question of whether or not these tumors should be classified as in situ or invasive melanoma. These cases highlight the complexity that such lesions pose to dermatopathologists, in terms of their uncertain origin and variable microscopic appearance. In the absence of data regarding outcomes for these tumors (given their rarity), it is important to utilize a case-by-case approach, with careful clinical correlation and appropriate use of ancillary techniques.

Triple Hedgehog Pathway Inhibition for Basal Cell Carcinoma.

Vismodegib, a potent inhibitor of the hedgehog pathway, is an effective treatment for advanced basal cell carcinoma. More recently, it has become recognized that other oral and topical medications exist that also inhibit this pathway. Multifocal inhibition has been shown to work more efficaciously than a single pathway inhibition when treating melanocytic tumors. The authors report the successful treatment of a patient with advanced basal cell carcinoma using the combination of vismodegib, itraconazole, and imiquimod, each of which inhibits a different part of the hedgehog pathway.

Concordance of frozen and permanent sections for the diagnosis of skin lesions.

BACKGROUND: There has been little written concerning the use of frozen sections to diagnose skin lesions. OBJECTIVE: To compare the concordance between frozen and permanent sections of the same diagnostic skin biopsy specimen. METHODS AND MATERIALS: Over 3 months, all non-melanocytic skin lesions that were biopsied in a skin cancer clinic were examined using frozen and permanent sections. Diagnoses from a dermatologist and dermatopathologist were recorded for each specimen and later examined for concordance. RESULTS: There was rare (0.5% of specimens) disagreement recorded between interpretations of the dermatologist and dermatopathologist. Permanent and frozen section pathology agreed with one another 90.4% of the time. Specimen processing was the most probable cause of discordance. Most discordance was not clinically relevant, although the patient was clinically affected in 35 of 2009 specimens (1.7%). CONCLUSION: Although there is a high concordance rate between diagnostic frozen and permanent sections, there are significant quality assurance and patient care advantages to following up initial diagnostic frozen sections with permanent sections of the same specimen.