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Diffuse Patterned Alopecia (DPA) is an androgenetic alopecia characterized by diffuse thinning in the front, top, and vertex of the scalp in conjunction with a stable permanent zone. Diffuse Patterned Alopecia is usually associated with the persistence of the frontal hairline represented by the hairline position of the Norwood Class II or Class III patient. Especially in the earlier stages, the thinning generally extends to the vertex without significant hair loss in the crown. It differs from the regular Norwood classification in that, when the hair loss is first noted, it is already in a stage resembling a thinning Norwood Class VI, rather than having progressed through the Norwood stages III, III Vertex, IV, and V, which are characterized by continued recession at the temples, an expanding vertex/crown, and the presence of a defined bridge separating the anterior and posterior portions of the scalp. In addition, there is an absence of the residual triangular elevation in the parietal region that helps to define the typical Norwood Class VI patient.

Diffuse Patterned Alopecia differs from the less common Diffuse Unpatterned Alopecia (DUPA) which is also androgenetic, but lacks a stable permanent zone. Diffuse Unpatterned Alopecia patients have a similar progression of balding as the DPA patient except that the progression is often more rapid and will more likely eventuate in a ?horseshoe pattern? resembling the Norwood class VII, except that in contrast to the Norwood VII, the DUPA ?horseshoe? can look almost ?transparent? due to the low density. The differentiation between DPA and DUPA is critically important because DPA patients are often good candidates for an appropriately timed transplant, whereas DUPA patients should almost never be transplanted because they will inevitably have extensive hair loss without a stable zone in which to harvest the hair.