"Blue nevus" was called to the attention of Tièche by his mentor Jadassohn. [4] In 1906, the trainee acted on the advice of his senior and published the observations of both of them in Virchow's Archive under the title, "About benign melanoma ('Chromatophorame') of skin-blue nevi." The drawings of the findings histopathologic show a proliferation congenital of melanocytes disposed mostly as solitary units dendritic (Tièche described them as "spindle") sometimes in a tangle, involving much of the reticular dermis, that lesion over the course of years coming to be known as "common blue nevus." In 1953, in the first edition of his tome, The Skin, Allen described and illustrated what he called "cellular blue nevus," the implication clear being that it represented yet another variant of "blue nevus." [5] Study of his photomicrographs reveals a congenital nevus, but one very different from so-called common blue nevus, the melanocytes oval and spindle-shaped being arranged in fascicles. In the subsequent 50 plus years, the notion of there being two types fundamental of "blue nevi," namely, "common" and "cellular," has taken hold firmly in all textbooks of general pathology, dermatopathology, and dermatology. But the concept of "blue nevus" as a generic and of "common" and "cellular" as two expressions most common of it (other variants being known as "combined blue nevus," "compound blue nevus," "dysplastic blue nevus," and blue neuro-nevus of Masson, to mention but four examples) are flawed irremediably. In brief, so-called blue nevus is not always blue (sometimes it is gray, brown, or even not pigmented), and "common" and "cellular" are not contrasting (the antonym of "common" is "uncommon" and of "cellular" is "acellular," the latter being incompatible with a proliferation of cells). More important still is that so-called cellular blue nevus qualifies as a melanocytic nevus, it being made up of fascicles of melanocytes, whereas so-called common blue nevus does not qualify as a nevus, it being composed near-wholly of markedly pigmented, bipolar, dendritic melanocytes disposed as solitary units, with nary a nest, fascicle, column, cord, or strand of melanocytes in conjunction with them. In sum and in short, there is no such thing as a "blue nevus," but rather a host of proliferations congenital of melanocytes, each with its own characteristics morphologic distinctive, some of them nevi, e.g., cellular blue nevus and deep penetrating nevus, and others not nevi, e.g., common blue nevus, nevus of Ota and nevus of Ito, despite their being designated "nevus."