This chapter reviews the group of primary cutaneous lymphomas, a unique category of lymphoproliferative disorders primarily presenting in the skin. It describes the classification system, differentiating between T-cell and B-cell lymphomas, and outlines the diagnostic criteria that emphasizes exclusive skin involvement in the absence of systemic disease. The most common subtypes are mycosis fungoides, primary CD30+ lymphoproliferative diseases (lymphomatoid papulosis and cutaneous anaplastic large cell lymphoma), and cutaneous marginal zone B-cell lymphoma. The chapter also addresses controversies regarding the origin of these lymphomas, proposing potential extracutaneous origins with subsequent skin tropism. Practical diagnostic workflows, including histopathological and molecular assessments, are emphasized, alongside prognostic considerations and therapeutic approaches that balance disease aggressiveness with patient-specific factors.