THE MORPHOLOGIC CRITERIA OF THE PSEUDOPOD IN SURFACE MICROSCOPY

Background and Design: In vivo cutaneous surface microscopy (oil epilu minescence, dermatoscopy, and dermoscopy) has been shown to greatly en hance the clinical diagnosis of melanoma. The pseudopod is a morpholog ic feature seen on surface microscopy that corresponds to the radial g rowth of tumor in melanoma. While it is one of the most specific surfa ce microscopic features of invasive melanoma, it has remained poorly d efined. We studied 239 pigmented lesions, 80 melanomas (62 invasive an d 18 in situ) and 159 randomly selected pigmented nonmelanomas. We pho tographed these lesions in vivo using immersion oil and a Heine Dermap hot camera (Heine Ltd, Hen: sching, Germany). We then scored the lesio ns in a ''blinded'' fashion for the presence of pseudopods based on st rictly defined morphologic criteria. Results: We defined the morpholog ic criteria of the pseudopod. As defined, the pseudopod retained a 97% specificity and 23% sensitivity for invasive melanoma. No difference was seen in the mean Breslow thickness between melanomas with and with out pseudopods. None of the in situ melanomas were observed to have ps eudopods. Conclusion: We suggest morphologic criteria for a highly spe cific in vivo cutaneous surface microscopic feature of invasive melano ma, the pseudopod.