Hồng ban lòng bàn tay (Palmar erythema)

Mô tả: A symmetrical and slightly warm area of erythema on the thenar and hypothenar eminences of the palm. • May have a mottled appearance or blanch when pressed. • Not associated with pain, itch or scaling. • May involve the palmar aspect of the fingers and proximal nail folds.85,86

Nguyên nhân: Documented in a large number of diseases; most common presentations include: • Primary causes (where disease of pathological processes cannot be found) • Hereditary – rare • Pregnancy – common • Senile • Secondary causes • Chronic liver disease • Autoimmune (e.g. rheumatoid arthritis) • Endocrinological – hyperthyroid • Neoplastic

Cơ chế: Regardless of the initial cause, palmar erythema is principally caused by increased perfusion of the palms. Central to many is increased oestrogen levels, increased oestrogen-to-testosterone ratios or raised circulating free oestrogens. Oestrogen has a known proliferative effect on endometrial capillary density, and it is thought that this effect may have a similar effect on the palms.87 Other causative factors that may play a role include: • disordered hepatic metabolism of bradykinin and other vasoactive substances87 • abnormal cutaneous vasoconstrictor vasodilator reflexes. Pregnancy Most likely due to increased circulating oestrogens, as discussed under ‘General the structure and function of skin and microvasculature.88 Palmar erythema 483 Liver disease Proliferation of capillary bed? Increased perfusion to palms Palmar erythema Increased oestrogen Raised oestrogen-to-testosterone ratio Increased free oestrogen Altered vasoconstrictorvasodilator response

Ý nghĩa lâm sàng: Palmar erythema, although non-specific, does have some value as a sign: • It has been seen to vary according to the severity of the underlying disease.87 • In rheumatoid arthritis it is associated with a more favourable prognosis with fewer digital deformities and higher haemoglobin levels.87 • It is a frequent sign of liver cirrhosis, with as many as 23% of ultrasound- proven cirrhosis patients having concurrent palmar erythema.88 • It is seen in 15% of patients with primary or metastatic brain malignancies.