Influence of Dermocorticoids on Bone Mineral Density in Patients With Bullous Pemphigoid

Glucocorticoids have direct effects on bone remodeling by suppressing bone formation (inhibition of osteoblastic differentiation, inhibition of mature osteoblasts function and apoptosis of mature osteoblasts) and by increasing bone resorption (decrease in osteoclast apoptosis and stimulation of osteoclastogenesis). They also have indirect bone effects by decreasing the intestinal absorption of calcium and increasing its urinary excretion, and by inhibiting the somatotropic and gonadotropic axis. This pathophysiology results in excessive bone fragility. Bone loss and increased incidence of fractures occur within 6 months after the introduction of oral corticosteroid therapy, with a partially reversible phenomenon within months of discontinuation. The extent of bone loss depends on the dose and duration of glucocorticoid administration. The systemic transition of topical corticosteroids depends on several parameters such as excipients, anatomical location, cutaneous state, the dose used and the duration of exposure. Clobetasol propionate, used for long-term use in bullous pemphigoid, is a Class IV dermocorticoid (highly potent). Patients with bullous pemphigoid will benefit from bone densitometry at the initiation of treatment, at 3 months (theoretical end of the treatment of attack) and at 6 months (theoretical end of the treatment). Patients will also benefit a blood test of serum calcium, phosphoremia, albumin, 25 OH vitamin D and cortisol at 8 to highlight possible correlations between changes in bone mineral density and phosphocalcic parameters and 8 cortisolemia (braking of the hypothalamic-pituitary-adrenal axis). Patients will also benefit from standard radiographs of the thoracic and lumbar spine at the initiation of treatment and at 6 months. Follow-up is planned over 6 months, with 2 follow-up visits at 3 months and 6 months.