Mycosis fungoides was previously misnamed as mycosis fungoides but has now been confirmed to be a primary cutaneous helper T-cell lymphoma. It predominantly occurs in young and middle-aged adults, though cases have been reported in individuals as young as their teens or as old as their 60s, with males being more affected than females. There are three types, the most common of which progresses from patches or plaques to tumors. Alternatively, tumors may develop directly, known as tumor-stage mycosis fungoides, which progresses more rapidly and has a poorer prognosis. Approximately 10% of cases may develop erythroderma, referred to as erythrodermic mycosis fungoides. The disease can persist for months to years, with an average duration of 4 to 10 years.

bubble_chart Clinical Manifestations

1. Erythematous stage: The morphology is diverse, presenting as light red or dark red scaly erythema. It can resemble eczema, psoriasis, parapsoriasis, ichthyosis, neurodermatitis, or erythroderma accompanied by stubborn cutaneous pruritus. In the chronic stage, it may appear poikilodermatous;
2. Patch stage: On the basis of erythema or normal skin, red or dark red infiltrative patches appear, varying in size. Sometimes the center heals, presenting as annular or horseshoe-shaped, with hair loss or ulcer formation in the infiltrated areas;
3. Tumor stage: Masses develop on infiltrative erythema or normal skin. In advanced stages, lymph node metastasis or invasion of internal organs (liver, lungs, spleen, bones, and central nervous system) may occur.

bubble_chart Diagnosis

1. The continuously evolving skin lesions, which are difficult to summarize under a single skin disease and do not respond to treatment, should raise suspicion for this condition;
2. The erythematous stage presents with faint red scaly erythema;
3. The patch stage manifests as red or dark red infiltrative patches;
4. The tumor stage shows masses on erythematous or normal skin;
5. Histopathology: A band-like infiltration of various cells in the dermis (including histiocytes, lymphocytes, eosinophils, and neutrophils, with atypical T cells visible) infiltrating the epidermis to form Pautrier microabscesses.

bubble_chart Treatment Measures

Treatment Principles

1. For the erythema stage and early patch stage, topical chemotherapy (nitrogen mustard alcohol solution) and photochemotherapy are the primary choices;
2. When topical chemotherapy and photochemotherapy are ineffective, electron beam irradiation combined with systemic chemotherapy is adopted;
3. For the patch stage or tumor stage, local radiotherapy, electron beam irradiation, or systemic medication is used.

1. Early and patch stage: Nitrogen mustard is the first choice for topical chemotherapy or photochemotherapy;
2. If topical chemotherapy, photochemotherapy, or electron beam irradiation fails, methotrexate or the COP regimen for systemic chemotherapy may be added;
3. 13-cis-retinoic acid, retinamidoester, and etretinate can serve as adjuvant therapy for all stages;
4. When using methotrexate, calcium folinate may be added as needed to counteract or prevent toxicity.

bubble_chart Cure Criteria

1. Cure: After treatment, the tumor or skin lesion completely disappears, and cytological examination is negative;
2. Improvement: After radiotherapy or chemotherapy, the lesion significantly shrinks;
3. No cure: After radiotherapy or chemotherapy, the lesion does not noticeably regress or shrink.