FREQUENCY AND MORPHOLOGIC CHARACTERISTICS OF INVASIVE MELANOMAS LACKING SPECIFIC SURFACE MICROSCOPIC FEATURES

Objectives: To create a simple diagnostic method for invasive melanoma with in vivo cutaneous surface microscopy (epiluminescence microscopy , dermoscopy, dermatoscopy) and to analyze the incidence and character istics of those invasive melanomas that had no diagnostic features by means of hand-held surface microscopes. Design: Pigmented skin lesions were photographed in vivo with the use of immersion oil. All were exc ised and reviewed for histological diagnosis. A training set of 62 inv asive melanomas and 159 atypical nonmelanomas and a test set of 45 inv asive melanomas and 119 atypical nonmelanomas were used. Images from t he training set were scored for 72 surface microscopic features. Those features with a low sensitivity (0%) and high specificity (>85%) were used to create a simple diagnostic model for invasive melanoma. Setti ng: All patients were recruited from the Sydney (Australia) Melanoma U nit (a primary case and referral center). Patients: A random sample of patients whose lesions were excised, selected from a larger database. Main Outcome Measures: Sensitivity and specificity of the model for d iagnosis of invasive melanona. Results: The model gave a sensitivity o f 92% (98/107) and specificity of 71%. Of the 9 ''featureless'' melano mas the model failed to detect, 6 were pigmented and thin and had a pi gment network. The other 3 were thicker, hypomelanotic lesions lacking a pigment network, some with prominent telangiectases, and all with o nly small areas of pigment. All featureless melanomas noted by the pat ients had a history of change in color, shape, or size. Conclusions: S urface microscopy does not allow 100% sensitivity in diagnosing invasi ve melanoma and therefore cannot be used as the sole indicator for exc ision. Clinical history is an important consideration when featureless lesions are diagnosed.