fungoides

Mycosis fungoides, the most common form of cutaneous T-cell lymphoma (CTCL), is a malignant proliferation of mature T lymphocytes that primarily involves the skin. It typically affects adults, especially older individuals, and ranges from indolent patch disease to more aggressive plaques and tumors.

Early mycosis fungoides presents as pale or red-brown patches or plaques that can resemble eczema or psoriasis. Itching is common. Lesions usually appear on the trunk and proximal limbs; hypopigmented variants occur in darker-skinned people. Over time, plaques may thicken or develop into tumors, with possible erythroderma and lymphadenopathy.

Diagnosis combines clinical exam with skin biopsy showing epidermotropism of atypical T cells. Immunophenotyping often shows CD3 positive, CD4 positive cells, with loss of some pan-T-cell markers; T-cell receptor gene rearrangement supports clonality. Staging uses the TNM system, including skin involvement, lymph nodes, visceral disease, and Sezary cells when present.

Treatment depends on stage. Early disease is managed with skin-directed therapies: potent topical steroids, topical bexarotene, nitrogen mustard, and phototherapy (narrowband UVB or PUVA). Local radiotherapy or total skin electron therapy may be used for extensive skin disease. Advanced disease may require systemic therapy such as bexarotene, interferon, histone deacetylase inhibitors (vorinostat, romidepsin), methotrexate, or combination chemotherapy. Extracorporeal photopheresis is used for Sezary syndrome and certain erythrodermic MF.

Prognosis varies by stage. Early MF often has a favorable prognosis with long survival, while progression to tumors, nodal involvement, erythroderma, or Sezary syndrome worsens outcomes. Ongoing follow-up with dermatology and oncology is recommended.