Cutaneous Lymphomas, Mastocytosis, and Histiocytosis

Cutaneous lymphomas are a heterogeneous group of lymphoproliferative neoplasms that are primarily localized to the skin. The most common types of cutaneous T-cell lymphoma are mycosis fungoides and Sézary syndrome. Mastocytosis and histiocytosis are proliferative disorders, most commonly seen in the pediatric age. Mastocytosis is characterized by the accumulation of mast cells in various tissues and is classified into cutaneous and systemic mastocytosis based on the site of involvement. Disseminated red-brown macules, pruritus, and positive Darier sign are the main features of urticaria pigmentosa. Langerhans cell histiocytosis is the most common type of histiocytosis that predominantly affects the skeletal system and skin, including lesions resembling seborrheic dermatitis.