Primary cutaneous lymphomas (PCLs) are an extremely heterogeneous group of non-Hodgkin lymphomas that manifest in the skin. Their diagnosis is complex and based on clinical lesion type and evaluation of findings on light microscopic examination, immunohistochemistry and molecular analysis of representative skin biopsies. The evaluation, classification, and staging system is unique for mycosis fungoides (MF) and Sézary syndrome (SS), the most common subtypes of cutaneous T-cell lymphoma (CTCL) versus the other subtypes of Non-MF/Non-SS CTCL and the subtypes of cutaneous B-cell lymphoma (CBCL). Since current treatment is stage-based, it is particularly important that the correct diagnosis and stage be ascertained initially. The purpose of this article is to review the current evaluation, diagnosis, classification, staging, assessment techniques, and response criteria for the various types of both T-cell and B-cell PCLs.