++
++
Hematology includes the study of blood and blood-forming tissues. Given the number and variety of hematologic disorders, it is not surprising that mucocutaneous manifestations of hematologic disorders are common. Many hematologic malignancies and pseudomalignancies can involve the skin through atypical cell infiltration (specific lesions), and some of these may present preferentially in the skin. These conditions, such as leukemias and lymphomas, plasma cell dyscrasias including myeloma, and Langerhans and non-Langerhans histiocytoses, are discussed in other chapters. Likewise, complications of chemotherapy, radiotherapy, cytokine use, or marrow transplantation are discussed elsewhere.
++
The first section of this chapter is directed toward the differential diagnosis of purpura with an emphasis on those subsets of purpura with important underlying hematologic abnormalities. The second major section of this chapter is directed toward nonspecific (nontumor-containing) findings that may be associated with hematologic disorders. Although the ready availability of laboratory testing has made early recognition of such conditions as anemia and polycythemia much less dependent on physical findings, cutaneous associations still may aid in the diagnosis of a hematologic condition or complicate its management. A comprehensive listing of these associations is presented in Table 144-1.
++