Integrating clinical, dermoscopy, and reflectance confocal microscopy findings into correctly identifying a nevoid melanoma

NeM: nevoid melanoma RCM: reflectance confocal microcopy INTRODUCTION Nevoid melanoma (NeM) is an uncommon subtype of melanoma that can mimic the morphology of an intradermal nevus both clinically and histopathologically. Similar to other melanoma subtypes, NeM is prone to local recurrence and metastasis, necessitating early diagnosis and prompt management. Recently, reflectance confocal microcopy (RCM) has shown to be a valuable noninvasive imaging device to help differentiate benign from malignant skin lesions with cellular resolution. Here we report a unique case of NeM that clinically mimicked an intradermal nevus. The appearance of the dermoscopic features of irregular globules and polymorphous vessels led to the expansion of the differential diagnosis, which included melanoma, irritated intradermal nevus, and an irritated clonal seborrheic keratosis. RCM imaging was performed to narrow the differential diagnosis and determine the true nature of the lesion. RCM revealed an atypical melanocytic neoplasm highly suspicious for melanoma, prompting a biopsy and averting a delay in diagnosis. This case highlights the importance of RCM as an adjunct tool that adds useful information to the clinical and dermoscopic findings. All of the gathered information (including features seen and features noticeably absent) were used in concert to arrive at the diagnosis of NeM via abductive reasoning or Bayesian inference.