Monoclonal gammopathy represents a condition characterized by clonal proliferation and accumulation of
immunoglobulin producing B-cells. A variety of skin disorders are associated with an increased level of monoclonal
immunoglobulin proteins. These skin disorders can be divided into two groups. The first group represents a direct consequence of plasma cell proliferation. The colonization of the plasma cell clone in the dermis expressed as a deposition of
proteins related to the M component belongs to this group for which the pathogenesis is well identified, as is the case for example with
AL amyloidosis and
cryoglobulins. The second group represents skin disorders such as
scleromyxedema and
Schnitzler syndrome that are highly associated with an M component, or diseases such as
pyoderma gangrenosum and
leukocytoclastic vasculitis that are more weakly associated with increased levels of monoclonal
immunoglobulins. In some other
dermatoses such as
pemphigus,
bullous pemphigoid,
epidermolysis bullosa aquisita,
Sezary syndrome,
lymphomatoid papulosis,
urticaria pigmentosa, and
acquired ichthyosis, only presumptions exist regarding associations with
monoclonal gammopathies. In this the pathogenesis,
therapy and prognosis of the most relevant
dermatoses shall be described in order of their degree of association with
monoclonal gammopathies, which shall also be discussed.