Systemic involvement in mycosis fungoides

Abstract Mycosis fungoides (MF) represents almost 50% of all primary cutaneous lymphomas and more than 70% of cutaneous T-cell lymphomas (CTCL). Arising from preferentially skin-homing lymphocytes with genetic instability, MF evolves through stages (IA-IVB), producing inconspicuous inflammatory features in the beginning and finally resulting in a proliferation of cytomorphologic, phenotypic, and genotypic abnormal tumor cells. Over the past 200 years, there has been much confusion in the classification of lymphomas due to semantic disagreements ( MF, CTCL, parapsoriasis, lymphosarcoma, reticulum cell sarcoma, and many other terms), lack of diagnostic standard criteria, and new molecular diagnostic methods. Studies on extracutaneous involvement in early stages (IA-IIA) are almost completely lacking. In advanced stages of MF (IIB-IVB), discovery of extracutaneous involvement is dependent on the methods used (physical examination, technology, molecular diagnostics, autopsy, and laparoscopy) and reveals a wide range of results. Due to the inflammation-simulating features in the beginning of the disease, early diagnosis is very difficult to assess. Extracutaneous involvement has previously been documented in more than 70% of autopsies. More recent studies give much lower figures. Like all lymphomas, MF is a systemic disease from the very beginning, with distinct homing preferences in tumor cells. Organs most commonly involved during the lengthy course of the disease are, in descending frequency, lymph node/peripheral blood, liver, spleen, lung, bone marrow, GI tract, pancreas, and kidney.