Dupixent Lymphoma (CTCL) Lawsuit

Cutaneous T-Cell Lymphoma (CTCL)

A group of non-Hodgkin lymphomas in which malignant T-cells settle in the skin. The lawsuits allege that Dupixent treatment may cause or accelerate it, and separately that it may mask the early signs of a case already present — both allegations under examination in MDL 3180, neither an established finding.

Common signs

• Scaly red patches or plaques that do not clear with treatment
• Persistent itching, often severe and worse at night
• Thickened or raised areas of skin
• A rash that spreads or changes shape over months or years
• Skin that was diagnosed as eczema or psoriasis and never responded

How it is identified: Skin biopsy read by a dermatopathologist, with immunohistochemistry and T-cell receptor gene rearrangement studies.

Severity: Varies by stage — early-stage disease is often managed for years with skin-directed therapy, while advanced disease is treated systemically.

Mycosis Fungoides

The most common form of cutaneous T-cell lymphoma, which typically progresses slowly through patch, plaque, and tumor stages and is frequently treated as eczema or psoriasis for years before it is correctly identified.

Common signs

• Flat, scaly patches, often on skin usually covered by clothing
• Patches that thicken into raised plaques over time
• Intense itching
• Patchy hair loss in affected areas
• Raised tumors or ulcers in later stages

How it is identified: Repeat skin biopsies over time, since early lesions can look identical to benign inflammatory skin disease under the microscope.

Severity: Usually indolent in its early stages; advanced-stage disease carries a materially worse prognosis.

Sézary Syndrome

An aggressive leukemic form of cutaneous T-cell lymphoma in which the malignant T-cells circulate in the blood as well as involving the skin.

Common signs

• Widespread red, intensely itchy skin covering most of the body
• Peeling or shedding skin
• Enlarged lymph nodes
• Changes to the nails, hair, or eyelids
• Fatigue and difficulty regulating body temperature

How it is identified: Skin biopsy plus blood testing (flow cytometry) showing Sézary cells in the circulation, with lymph node evaluation.

Severity: Serious — the aggressive form of CTCL, generally requiring systemic treatment.

Delayed Lymphoma Diagnosis

Not a disease but a harm, and it is in this list because it is the second limb of what the lawsuits plead: that Dupixent may suppress the skin symptoms of a cutaneous T-cell lymphoma a patient already has, so the rash improves, the biopsy is not ordered, and the lymphoma is not identified until it has advanced. That allegation is why someone whose diagnosis came before she ever started Dupixent is not automatically outside this litigation.

Common signs

• A long-standing rash that improved on Dupixent and then returned or worsened
• Years of treatment for eczema or dermatitis before any biopsy was taken
• A lymphoma identified at a later stage than the timeline of symptoms would suggest
• Symptoms that were repeatedly attributed to an inflammatory skin condition

How it is identified: Established by the treatment record rather than by a test — the sequence of prescriptions, symptom notes, and the date the biopsy was finally ordered.

Severity: Depends on how much stage progression occurred in the interval; it is a question for medical review of the records, not for a screening form.

You were treated with Dupixent

You were prescribed Dupixent or dupilumab, for eczema or atopic dermatitis or for one of its other approved uses. Your pharmacy record names it if you are not certain.

A lymphoma was diagnosed

You were diagnosed with a lymphoma. It may have been called mycosis fungoides or Sézary syndrome rather than lymphoma — the subtype name is what most people are told.

The two dates, in either order

Roughly what year you started the medication, and roughly what year you were diagnosed. Either order can support a claim: a diagnosis that came first goes to the delayed-diagnosis theory rather than ruling you out.

The records can be identified

The pathology or biopsy report for the lymphoma, and the prescription record for the Dupixent. You do not need either in hand today — knowing which doctors have them is enough.