Biomedical subjects

Nathalie Saad

Publications and source records attributed to Nathalie Saad.

4 recordsLinked to original sources

PubMed2006

Multiple adult xanthogranuloma: case report and literature review.

BACKGROUND: Non-Langerhans cell histiocytoses form a heterogeneous group defined by the proliferation of cells with macrophage characteristics. Diagnosis is easy in typical cases but becomes more complex in unusual forms. CASE REPORT: We report the case of a 53-year-old patient who presented multiple brown-to-yellowish papules and nodules of the trunk, neck, and head evolving for 6 months. No visceral involvement was found. Histopathological examination revealed histiocytic proliferation with features of secondary xanthomization with the presence of giant foamy multinucleated Touton cells. One year later, all lesions cleared spontaneously. Based on the clinical presentation and evolution and on the immunohistologic data, we retain the diagnosis of adult xanthogranuloma (AXG) in a diffuse shape. DISCUSSION: Multiple AXG is a rare entity (15 cases reported since 1963) with a stereotypic presentation. It is important to recognize because of its good prognosis and the absence of visceral involvement therefore requiring no investigations or aggressive treatments. This case is interesting because of the complete and spontaneous healing of all the lesions within 20 months.

Antigens, CD↗

PubMed2006

Pathophysiology of urticaria.

Urticaria is dermal edema resulting from vascular dilatation and leakage of fluid into the skin in response to molecules released from mast cells. The major preformed mediator histamine produces a prototypic, short-lived urticaria. However, the clinical spectrum and pattern of lesions indicate that other molecules, including prostaglandins, leukotrienes, cytokines, and chemokines, produced at different times after mast cell activation contribute to the polymorphism of this symptom and the variable evolution of this disease. It is a common practice to distinguish immunological and nonimmunological urticaria. Immunological urticaria is a hypersensitivity reaction mediated by antibodies and/or T-cells that results in mast cell activation. Although immunoglobulin (Ig)E-mediated type I hypersensitivity (HS) was long postulated to be the major immunological pathway associated with mast cell activation, interaction between IgE-bound mast cells and allergens is unlikely to be the mechanism by which urticaria develops in most patients. It is now well established that urticaria may result from the binding of IgG auto-antibodies to IgE and/or to the receptor for IgE molecules on mast cells, thus corresponding to a type II HS reaction. These auto-immune urticarias represent up to 50% of patients with chronic urticaria. Mast cell activation can also result from type III HS through the binding of circulating immune complexes to mast cell-expressing Fc receptors for IgG and IgM. Finally, under certain circumstances, T-cells can induce activation of mast cells, as well as histamine release (type IV HS). Nonimmunological urticarias result from mast cell activation through membrane receptors involved in innate immunity (e.g., complement, Toll-like, cytokine/chemokine, opioid) or by direct toxicity of xenobiotics (haptens, drugs). In conclusion, urticaria may result from different pathophysiological mechanisms that explain the great heterogeneity of clinical symptoms and the variable responses to treatment.

Cell Degranulation↗

PubMed2004

[How to understand psoriasis?].

Recent advances in the treatment of psoriasis have led to improve understanding in the pathogenesis of the disease. Skin lesions are scaling erythematous plaques. Although initially considered as a disease of epidermal cells, it is now widely accepted that the epidermal abnormalities, which are characteristic of the disease, are secondary to the development of a skin inflammation. Psoriasis is an autoimmune disease due to the activation in the skin of antigen-specific T cells leading to release of cytokines that results in proliferation of keratinocytes. However, the autoantigen(s) is (are) yet unknown. Several new biological treatments have been developed, which target specific steps in the pathophysiology of the disease.

Cytokines↗

PubMedDate not supplied

Methotrexate for the treatment of adult atopic dermatitis.

Atopic dermatitis (AD) is a chronic inflammatory skin disease mediated by allergen-specific T cells which are recruited and activated in lesional skin. Methotrexate (MTX) is an old systemic agent used at low dosage for the treatment of psoriasis, another T cell-mediated skin disorder. Since MTX has been shown to improve the clinical symptoms of eczema in a model of antigen-specific dermatitis in mice, we postulated that it could be an effective treatment of AD. In the present open retrospective study, we report our results on the treatment of moderate to severe AD by MTX. Twenty patients (17 to 68-years-old) with low responses to routine therapies were treated (three months to 2 1/2 years) with a weekly dose of MTX ranging from 7.5 to 25 mg. The evaluation was made on physician's global assessment after 3 months of MTX use, and showed that 75% (15/20) of patients improved after 3 months of MTX use, among which 13/20 with an improvement>70%. The beginning of improvement was observed between the fourth and the eighth week after MTX was initiated. Tolerance was good. However, nausea and increase of liver enzymes were observed in 5 patients and required discontinuation of MTX in 2 patients. In conclusion, MTX seems to be an effective and safe treatment of AD. Placebo-controlled clinical trials are needed to confirm our observations and to define more precisely the effectiveness and safety of MTX in adult AD.

Adolescent↗