In two dimensions, a digon is a polygon with two sides (or edges) and two vertices. On a circle, it is a tessellation with two antipodal points and 180° arc edges. The simplest tessellation in two-dimensional space, though an improper tessellation, is that of two 
  
    
      
        ∞
      
    
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  -sided apeirogons joined along all their edges, coincident about a line   that divides the plane in two. This order-2 apeirogonal tiling is the arithmetic limit of the family of dihedra {p, 2}. For any polyhedron homeomorphic to a sphere, the Euler characteristic is χ = V − E + F = 2, where V is the number of vertices, E is the number of edges, and F is the number of faces. The long diagonal of a regular hexagon is of length two when its sides are of unit length. Whereas a square of unit side length has a diagonal equal to the square root of two, and a cube of unit side length has a space diagonal equal to the square root of three, a space diagonal inside a tesseract measures two when its side lengths are of length one. There are two known sublime numbers, which are numbers with a perfect number of factors, whose sum itself yields a perfect number.
Pagetoid reticulosis (also known as "acral mycoses fungoides", "localized epidermotropic reticulosis", "mycosis fungoides palmaris et plantaris", "unilesional mycosis fungoides", and "Woringer–Kolopp disease") is a cutaneous condition, an uncommon lymphoproliferative disorder, sometimes considered a form of mycosis fungoides. : 734

Symptoms and Signs
Lesions emerge as well-demarcated psoriasiform or hyperkeratotic patches and plaques, with a central clearing and an elevated border. Pagetoid reticulosis is a very slow progressive variant of mycosis fungoides and is usually localized unlike the latter. Treatment
The most common method of treatment includes radiotherapy and/or surgical excision. See also
Pagetoid
Cutaneous T-cell lymphoma
List of cutaneous conditions

References


== External links ==