The early lesions of mycosis fungoides mimic psoriasis, chronic eczema, atopic dermatitis, leprosy or lichenoid pityriasis. The typical skin involvement is thin erythematous plaques or flat patches. They present either as single or multiple lesions in the gluteal region or thighs. The lesions can be pruritic and can remain stable for many years, go into remission, or grow slowly.

Sezary syndrome is an erythrodermic cutaneous T-cell lymphoma with the leukemic component. Erythroderma is an intense, widespread, pruritic, exfoliative rash representing new lesions or progression of the prior patches or plaques.

It is characterized by erythroderma, lymphadenopathy, Sezary, or Lutzner cells which are atypical circulating lymphocytes and cutaneous and systemic dissemination of CD4+ T cells in the blood and the lymph nodes. Mycosis fungoides is like a patch or a plaque, whereas Sezary syndrome presents as a diffuse skin rash. During the disease, it tends to involve about 80% of the total body surface area. Sezary syndrome can be considered as a leukemic phase of cutaneous T-cell lymphoma without any bone marrow compromise. Involvement of the bone marrow can be seen in advanced disease. The other skin lesions associated with Sezary syndrome include alopecia, keratoderma, hypertrophied nails, lichenification, and ectropion (outward turning of the lower eyelid). Very rarely, it could also involve the visceral organs. Pruritus is intense and can be debilitating. Even high doses of antihistamines cannot provide relief. Treatment of underlying cancer with steroids have shown to be effective in controlling the pruritus. Due to suppressed immunity, affected people are at higher risk for secondary infections (bacterial and viral) and secondary cancers including Hodgkin and non-Hodgkin lymphomas.

Any patient presenting with erythroderma should raise the suspicion of Sezary syndrome. Though the skin involvement is diffuse in Sezary syndrome, it is not as dense as it is in mycosis fungoides. Therefore, a skin biopsy should be performed without any interventions for the lesions, and the site with the greatest induration should be biopsied.[8][9][10]

Excisional lymph node biopsy is preferred, and it can show reactive changes or dermatopathic changes or features suggestive of lymphoma.

Peripheral blood shows atypical circulating lymphocytes with grooved nuclei, called Sezary or Lutzner cells. A rarely smaller variant of Sezary cells can be seen in normal people or people with known malignancy.[11][12]

Immunophenotyping confirming T-cell origin (CD3+ and CD4+) and lack of expression of CD2, CD3, CD5 and CD7 (mature T-cell antigens) are supportive of Sezary syndrome.

The diagnosis is made by erythroderma involving greater than 80% BSA, clonal TCR rearrangement confirmed by PCR or Southern blot, and absolute Sezary cell count of at least 1000 cells/microL, or one of the following 2 criteria:

• Increased CD4+ or CD3+ with CD4/CD8 ratio of 10 or more
• Increased CD4+ cells with abnormal phenotype: CD4+CD7 ratio of 40% or more or CD4+CD26 ratio of 30% or more.

The staging of Sezary syndrome and mycosis fungoides is done by evaluating the skin (T), lymph nodes (N), visceral organ involvement (M), and blood (B). Types of skin lesions and extent of its involvement determines the “T” stage. Blood involvement depends on the tumor burden of the blood. Patients with Sezary syndrome are considered to have stage IVA1, IVA2 and IVB depending on the presence of nodal and visceral involvement.

The treatment options are based on the stage of the disease. Given the leukemic involvement in Sezary syndrome, the treatment is generally systemic. It can be given alone or in a combination of skin-based therapy. Stage IVA (no visceral involvement) patients are usually treated with extracorporeal phototherapy (ECP) combined with biological response modifiers (retinoids and interferons). Other alternatives include low-dose methotrexate and histone deacetylase inhibitors (vorinostat and romidepsin). Various combinations of the above can be used along with skin-directed therapy.

• Skin-directed therapy includes topical or systemic steroids, topical nitrogen mustard, phototherapy (UVB and PUVA) and total skin electron beam therapy (TSEBT).
• Radiation therapy can be used for local control of skin and nodal disease.
• Patients with stage IVB (visceral involvement) are usually treated with histone deacetylase (HDAC) inhibitors or single-agent chemotherapy.
• In the relapsed and refractory setting, various single-agent chemotherapies can be used like doxorubicin, gemcitabine and purine/pyrimidine analogs. FDA-approved drugs in this setting include intermediate-dose methotrexate and pralatrexate. Other investigational options include pembrolizumab, alemtuzumab, bortezomib, and brentuximab vedotin.
• Young patients with the high-risk disease should be offered allogeneic hematopoietic stem cell transplantation at experienced centers.

Besides these disease-directed treatment options, pruritis is a big concern in patients with Sezary syndrome. Various local and/or systemic options can be used to control the pruritis.[13]

Sezary syndrome should be differentiated from mycosis fungoides, psoriasis, pityriasis rubra pilaris, dermatitis, hypereosinophilic syndrome, and adult T-cell leukemia.

Cutaneous T cell lymphomas are best managed by an interprofessional team that includes oncology nurses. Clinicians looking after patients with cutaneous T cell malignancies should not forget that improve the quality of life. These patients have severe pruitus, which can be disabling. Thus, the patient should be educated on how to moisturize the skin and prescribed medications to relieve the itch. During treatment of the malignancy, the patient's quality of life should be a consideration.

The outlook for most patient is guarded.