We read with interest the detailed review article on Merkel cell carcinoma (MCC) published by Llombart et al.1 in March, 2017, in Actas Dermo-Sifiliográficas. The authors describe the clinical characteristics of this skin neoplasm as an isolated, well-defined, firm nodular tumor of erythematous, violaceous, or purpuric color. It is not adherent to deeper planes. In agreement with this description, MCC lacks specific clinical characteristics. As also discussed by Llombart et al., the acronym AEIOU (Asymptomatic, Expanding rapidly, Immunosuppression, Older than 50, and UV exposure) has recently been defined.2 However, the diagnostic suspicion of MCC is top of the list of differential diagnoses in only 1% of all cases.2 The most important distinctive characteristic highlighted by various authors is that it tends to be a rapidly growing, asymptomatic tumor (63% of patients in a survey reported rapid growth of their tumors within 3 months).2 As few studies have focused on the clinical characteristics of MCC, we decided to analyze the characteristics of our series of patients with MCC. We observed 2 distinct clinical patterns depending on whether the tumors were in sun-exposed areas or non-exposed areas.3 In our experience, tumors in sun-exposed areas of skin typically present as tumors with superficial erosions and a tendency to bleed, whereas those in non-sun-exposed areas tend to present as nodular lesions, frequently lobulated, with a smooth, shiny surface with no erosions. All showed rapid growth. Sun-exposed lesions tended to be of less than 2cm in diameter (perhaps because they were more easily detected by the patient) and were more common in older men, whereas non-sun-exposed tumors are larger and tended to affect younger patients. Sun-exposed lesions were difficult to distinguish from more common skin tumors, such as squamous cell carcinoma. However, most non-sun-exposed tumors presented as nodular lesions with a smooth and shiny surface with no erosions, and many were lobulated. In our experience, this clinical appearance in a rapidly growing tumor is relatively specific and should suggest a clinical diagnosis of MCC before performing biopsy.