Some have postulated an infectious agent as the cause. Atopic dermatitis may confer an increased risk because of the chronic stimulation of T cells. Males are more commonly affected than females by a 2:1 ratio. A worse prognosis is associated with advanced age. Children and adolescents may be affected as well.
With mycosis fungoides, there are three main types of skin lesions: patch, plaque, and tumor. Patients will progress from patch to plaque to tumor stage in classic MF. Often, lesions begin as scaly, erythematous patches that resemble eczema. Because of the nonspecific nature of early lesions, the median duration from the onset of skin lesions to the diagnosis of MF is 4-6 years. Patch stage lesions may be pruritic or asymptomatic. Commonly, they present in non–sun-exposed areas, such as the buttocks. Annular, infiltrated, red-brown or violaceous plaques can develop, which represent malignant T-cell infiltration. Many patients never progress past the plaque stage. Tumor stage MF is more aggressive, with nodules that may undergo necrosis and ulceration.
The leukemic form of MF is Sézary syndrome. Patients present with pruritic erythroderma and lymphadenopathy. Nail dystrophy, scaling of palms and soles, and alopecia may be present. A peripheral blood smear reveals Sézary cells, which are large, hyperconvoluted lymphocytes. The count of Sézary cells is usually greater than 1000 cells/mm3.
Histology of early lesions may not be diagnostic for CTCL. Often, biopsies will be read as eczematous or psoriasiform for years before the diagnosis of MF is made. Classically, epidermotropism (single-cell exocytosis of lymphocytes into the epidermis) is present. Advanced stages may show a dense infiltrate of lymphocytes in the dermis. Groups of lymphocytes in the epidermis form Pautrier’s microabscesses. Mycosis cells may exhibit cerebriform nuclei. Neoplastic cells in MF are CD3+, CD4+, CD45RO+, CD8–. Tissue can be sent for T-cell gene rearrangement polymerase chain reaction. The presence of monoclonal T-cell gene receptor rearrangements can aid in the diagnosis of MF.
Treatment includes topical steroids, mechlorethamine (nitrogen mustard) or bexarotene gel, PUVA therapy, and narrow-band UVB light for limited and/or patch disease. Localized radiotherapy can be used for more resistant lesions. Topical therapies are preferred in the early stages in MF. Systemic treatments for patients who do not respond to local therapy, or in more advanced disease include methotrexate, interferon-alpha, oral bexarotene, denileukin diftitox, and combination chemotherapy. Photopheresis is reserved for erythrodermic disease.
Dr. Donna Bilu Martin
This case and photo were submitted by Dr. Bilu Martin.
Dr. Bilu Martin is a board-certified dermatologist in private practice in Aventura, Fla. More diagnostic cases are available at edermatologynews.com. To submit a case for possible publication, send an email to dermnews@mdedge.com.