Mycosis fungoides: The pathology of extracutaneous involvement

A survey of the autopsy material of 45 clinically and histologically typical cases of mycosis fungoides (M.F.) revealed extracutaneous involvement in 32, or 71%. The lymph nodes showed diagnosable M.F. in 24 of these 32 cases. Viscera most commonly involved were, in order of decreasing frequency: lung, spleen, liver, kidney, thyroid gland, pancreas, bone marrow, and heart. Practically all organs and tissues of the body were found to be involved. Lesions of the lymph nodes and viscera have a characteristic, if not a specific cellular composition which closely resembles that of cutaneous lesions. The neoplastic cells are of lymphocytic origin. Among them, the hyperchromatic mycosis cells and the cells with convoluted, deeply indented, and cerebriform nuclei have considerable diagnostic value. They are usually essential for the differentiation of the cellular proliferation of M.F. from those of other malignant lymphomas. Mycosis fungoides is a pathologic as well as a clinical entity; the neoplastic cellular proliferation in both cutaneous and extracutaneous tissue is distinct and different from those of other lymphoid and histiocytic neoplasms which usually arise in extracutaneous sites, but occasionally also in the skin.