IMPORTANCE VEXAS (vacuoles, E1 enzyme, X-linked, autoinflammatory, somatic) is a recently described severe adult-onset autoinflammatory disease that is associated with myeloid lineage-restricted ubiquitin-activating enzyme 1 (UBA1) somatic variations that primarily affect the skin (Sweet syndrome), cartilage, and bone marrow. Skin symptoms have been poorly described.OBJECTIVE To better describe clinical and pathological skin manifestations and their pathophysiology in VEXAS syndrome. DESIGN, SETTING, AND PARTICIPANTSThis multicenter retrospective case series study of clinical and histological features of 8 patients with VEXAS syndrome and skin involvement was conducted in France from December 2007 to March 2021, with molecular data obtained from March to April 2022. Any UBA1 variations were detected by Sanger or next-generation sequencing that was performed on bone marrow and formalin-fixed paraffin-embedded tissue sections of skin lesion biopsies.RESULTS All 8 patients were men, and the median age at symptom onset was 65.5 years (interquartile range, 54-76 years). All patients had neutrophilic dermatosis skin lesions, including tender red or violaceous papules, sometimes edematous, without fever, arthralgia, recurrence or pathergy, inflammatory edematous papules on the neck and trunk (sometimes umbilicated), and firm erythematous purpuric or pigmented infiltrated plaques and nodules. Three patients had livedo racemosa. The infiltrates were perivascular and consisted of mature neutrophils with leukocytoclasia, which were admixed with myeloperoxidase-positive CD163-positive myeloid cells with indented nuclei and lymphoid cells in all cases. A sequencing analysis of paired bone marrow samples and skin lesion biopsies identified the same loss-of-function UBA1 variation in both samples for all patients.CONCLUSIONS AND RELEVANCE This case series study describes the different clinical presentations of skin lesions found in VEXAS syndrome, which is characterized histologically by neutrophilic dermatosis. The findings suggested that the dermal infiltrates seen in VEXAS skin lesions are derived from the pathological myeloid clone. This suggests that using therapies that target the pathological clone may be effective in the long-term management of the disease.

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Scleromyxedema is a rare skin and systemic mucinosis that is usually associated with monoclonal gammopathy (MG). In this French, multicenter, retrospective study of 33 patients, we investigated the clinical and therapeutic features of MG-associated scleromyxedema. Skin molecular signatures were analyzed using a transcriptomic approach. Skin symptoms included papular eruptions (100%), sclerodermoid features (91%), and leonine facies (39%). MG involved an IgG isotype in all patients, with a predominant λ light chain (73%). Associated hematologic malignancies were diagnosed in 4/33 patients (12%) (smoldering myeloma, n=2; chronic lymphoid leukemia, n=1; and refractory cytopenia with multilineage dysplasia n=1). Carpal tunnel syndrome (33%), arthralgia (25%) and dermato-neuro syndrome (DNS) (18%) were the most common systemic complications. One patient with mucinous cardiopathy died of acute heart failure. Intravenous immunoglobulin (HDIVig) treatment alone or in combination with steroids appeared to be quite effective in nonsevere cases (clinical complete response achieved in 13/31 patients). Plasma cell-directed therapies using lenalidomide and/or bortezomib with dexamethasone and HDIVig led to a significant improvement in severe cases (HDIVig-refractory or cases with central nervous system or cardiac involvement). The emergency treatment of DNS with combined plasmapheresis, HDIVig, and high-dose corticosteroids induced the complete remission of neurological symptoms in 4/5 patients. Quantitative reverse transcriptase-PCR (RT-PCR) analysis of 6 scleromyxedema skin samples showed significantly higher profibrotic pathway levels (transforming growth factor β (TGFβ) and collagen-1) than in healthy skin. Prospective studies targeting plasma cell clones and/or fibrotic pathways are warranted for long-term scleromyxedema management.