The term ‘combined nevus’ was created to describe a blue nevus associated with a common nevus (nowadays presumably interpreted as Clark nevus) or a Spitz nevus. Other authors have extended the use of this term also to benign melanocytic nevi with two or more cell populations, a rather common finding within the spectrum of congenital nevi.
A combined nevus, as a rule, comprises at least two or more components, usually reflected by different colorations. In most instances, a combined nevus consists of an otherwise typical blue nevus associated with a Clark or a Spitz nevus. For the latter combination, however, no clear-cut clinical diagnosis can be made. Basically, also other combinations or associations of the various types of melanocytic nevi may be encompassed under the term ‘combined nevus’, e.g., Spitz nevus arising in a nevus spilus, as recently reported by Hofmann-Wellenhof et al. [Dermatology 1994]. From a clinical point of view, combined nevi are simulators of melanomas especially due to the markedly variegated coloration suggestive of melanoma in a pre-existing nevus of any type.
Depending on the types of nevi making up a combined nevus, its dermoscopic features may be diagnostic. Independently of the nature of the combined nevus, the overall architecture (global features) often shows a multicomponent pattern that becomes more evident by dermoscopic examination. In a combined nevus, composed of a blue nevus and a Clark nevus, dermoscopy reveals the stereotypical findings of a blue nevus, namely, a homogenous blue-gray pigmentation devoid of any local features, in association with a typical pigment network reflecting the Clark nevus. Especially when the pigment network is situated at the periphery of the lesion and, moreover, shows network variations, a combined nevus may mimic a melanoma. In other examples of the same association, the blue nevus is located in the center, completely surrounded by an otherwise stereotypical Clark nevus. Obviously, other associations within the spectrum of combined nevi reveal different dermoscopic features in accordance with the underlying type of nevus.