Pastia's lines

A clinical sign associated with scarlet fever

Pastia's lines

Pastia's lines on the arm of a patient with scarlet fever

Pastia's lines are a clinical sign associated with scarlet fever, a disease caused by infection with the bacterium Streptococcus pyogenes. These lines are characterized by the presence of pink or red lines of confluent petechiae found in the skin folds, particularly in the antecubital fossa (the inner aspect of the elbow) and other flexural areas of the body.

Clinical presentation

Pastia's lines appear as a result of the rash associated with scarlet fever, which is a diffuse erythematous rash that feels like sandpaper. The lines are more prominent in areas where the skin is creased or folded, such as the axillae, groin, and neck. They are caused by the leakage of blood from capillaries that have been damaged by the toxins produced by the bacteria.

Pathophysiology

The pathophysiology of Pastia's lines involves the exotoxins produced by Streptococcus pyogenes, which lead to capillary fragility and the formation of petechiae. These petechiae coalesce to form the characteristic lines in areas of skin folding. The immune response to the bacterial infection also plays a role in the development of the rash and Pastia's lines.

Diagnosis

The presence of Pastia's lines can aid in the clinical diagnosis of scarlet fever, especially when accompanied by other symptoms such as a sore throat, fever, and the characteristic rash. A throat culture or rapid antigen detection test can confirm the presence of Streptococcus pyogenes.

Treatment

Scarlet fever, and consequently Pastia's lines, are treated with antibiotics, typically penicillin or amoxicillin. Treatment helps to reduce the duration of symptoms and prevent complications such as rheumatic fever.

Related pages

• Scarlet fever
• Streptococcus pyogenes
• Rash
• Petechiae