Histopathologic interobserver agreement on the diagnosis of melanocytic skin lesions with equivocal dermoscopic features: A pilot study

Aims and background: Dermoscopy (dermatoscopy, skin surface microscopy, epiluminescence microsco py) has been increasingly employed in recent years for the preoperative det ection of cutaneous melanoma, and dermatoscopic features of pigmented skin lesions have been previously defined using histopathology (HP) as the "key to the code". The aim of the present study was to evaluate the interobserve r agreement on the HP diagnosis in a series of epiluminescence microscopy e quivocal melanocytic skin lesions. Study design: Ten melanocytic skin lesions were selected on the basis of di agnostic disagreement of at least 2 out of 9 epiluminescence microscopy obs ervers. The histologic specimens from the 10 lesions were examined by 9 HP observers. The agreement of the HP diagnoses was calculated by means of Fle iss' k statistics. Results: The overall HP agreement was less than excellent (k = 0.5). When c onsidering the prevailing epiluminescence microscopic and HP diagnoses, 2 c ases were shown to be epiluminescence microscopy false-negative melanomas, Virtually no agreement was found among epiluminescence microscopy observers in 4 cases (40%) or among HP observers in 3 cases (30%), However, only one pigmented skin lesion remained unclassifiable on epiluminescence microscop y as well as HP. Conclusions: When at least 2 epiluminescence microscopy experts disagree in the evaluation of a given metanocytic skin lesion, even HP consultations m ay give equivocal results. The need to establish more reliable epiluminesce nce microscopic and HP criteria by performing an improved and meticulous cl inicopathologic correlation, e.g. by using telecommunication via Internet, is emphasized.