Mycosis Fungoides and Dupixent Lawsuits

Mycosis fungoides is the most common type of cutaneous T-cell lymphoma, a cancer that begins in the T-cells of the immune system and shows up in the skin. It is usually slow-growing and develops over time, often moving through stages. In its early stages it appears as flat, scaly patches. As it progresses it can form raised plaques and, in later stages, tumors on the skin. In advanced disease it can spread to the lymph nodes, blood, or internal organs.

What makes mycosis fungoides especially relevant to the Dupixent litigation is how easily it is mistaken for something else. In its early stages it can look almost identical to eczema, psoriasis, or ordinary dermatitis. Many patients are treated for a benign skin condition for months or years before a biopsy reveals the truth.

Dupixent is frequently prescribed for eczema. Early mycosis fungoides often looks like eczema. That overlap sits at the center of the lawsuits. Plaintiffs allege two related harms. First, that Dupixent may trigger or accelerate T-cell lymphoma in some patients. Second, that by calming the visible skin symptoms, the drug may have masked an underlying mycosis fungoides, delaying the biopsy and diagnosis that could have caught the cancer earlier.

Peer-reviewed studies have reported elevated rates of cutaneous T-cell lymphoma, including mycosis fungoides, among patients treated with Dupixent. As of June 2026, the FDA-approved label for Dupixent still does not carry a specific warning about CTCL or lymphoma, even though the FDA has identified CTCL as a potential safety signal tied to the drug. The lawsuits allege the manufacturers had access to this information and did not adequately warn.

On June 4, 2026, federal Dupixent T-cell lymphoma cases were consolidated into MDL No. 3180 in the U.S. District Court for the District of New Jersey before Judge Zahid N. Quraishi. The defendants are Regeneron Pharmaceuticals and Sanofi-Aventis U.S. The litigation is in its early stages, which makes this a timely moment to have your potential claim reviewed. No settlements have been reached, and no outcome is guaranteed.