Differential Diagnosis for Lacy Rash on Legs of Teenage Female with Vomiting
Single Most Likely Diagnosis
- Henoch-Schönlein Purpura (HSP): A form of vasculitis that often presents with a lacy, purpuric rash on the legs, along with gastrointestinal symptoms like vomiting, abdominal pain, and sometimes joint pain. It is more common in children and young adults, making it a likely diagnosis for a teenage female.
Other Likely Diagnoses
- Erythema Multiforme: An immune-mediated condition characterized by a skin rash, which can sometimes appear lacy, and is often accompanied by mucosal involvement and systemic symptoms like vomiting. It can be triggered by infections or medications.
- Insect Bite Reaction: Certain insect bites can cause a lacy or reticular rash, especially if the individual has a hypersensitivity reaction. Vomiting could be a part of a systemic allergic reaction.
- Contact Dermatitis: An allergic reaction to substances in contact with the skin can cause a rash, which might appear lacy, along with systemic symptoms if the reaction is severe.
Do Not Miss Diagnoses
- Meningococcemia: A severe infection caused by Neisseria meningitidis, which can present with a petechial or purpuric rash (that might appear lacy) and systemic symptoms including vomiting. It is life-threatening and requires immediate medical attention.
- Thrombotic Thrombocytopenic Purpura (TTP): A rare blood disorder characterized by the formation of blood clots in small blood vessels throughout the body, which can lead to a rash, vomiting, and other systemic symptoms. It is critical to diagnose and treat promptly.
- Disseminated Intravascular Coagulation (DIC): A condition characterized by both widespread clotting and bleeding in the vascular system, which can cause a rash and vomiting among other symptoms. It often occurs in the context of a severe underlying condition.
Rare Diagnoses
- Livedoid Vasculopathy: A rare condition characterized by inflammation of the blood vessels, which can cause a lacy, reticular rash, typically on the legs. Systemic symptoms like vomiting are less common but can occur.
- Sneddon's Syndrome: A rare condition that combines livedo reticularis (a mottled, lacy discoloration of the skin) with neurological symptoms and sometimes systemic symptoms. Vomiting might not be a primary symptom but could occur in the context of other systemic involvement.