Understanding the appearance of petechiae
Before delving into specific causes, it is important to recognize petechiae. Unlike a typical skin rash, petechiae are caused by bleeding under the skin and will not fade or change color when you press on them. These pinpoint-sized spots, usually less than 2mm, result from ruptured capillaries leaking blood into the skin or mucous membranes. While a benign cause like vigorous coughing can be responsible, the appearance of petechiae, especially in combination with other symptoms, should not be ignored.
Hematological and blood-related disorders
Many of the most serious causes of petechiae are related to the blood and blood-forming organs.
Thrombocytopenia
Thrombocytopenia, or a low platelet count, is a primary cause of petechiae. Platelets are essential for blood clotting, and when their levels drop too low, blood can leak from capillaries. Conditions leading to this include:
- Immune Thrombocytopenia (ITP): An autoimmune disorder where the body attacks its own platelets.
- Leukemia: Cancers of the blood and bone marrow, such as leukemia, can impair the bone marrow's ability to produce platelets.
- Disseminated Intravascular Coagulation (DIC): A complex and severe condition causing widespread clotting followed by widespread bleeding, leading to a rapid consumption of platelets.
Other bleeding and coagulation issues
- Congenital syndromes: Some genetic conditions, such as Wiscott-Aldrich and Fanconi anemia, can affect blood cell production and lead to low platelets.
- Liver disease: Severe liver disease can impair the production of clotting factors, contributing to bleeding.
Infections as a cause
Infectious diseases, both viral and bacterial, are frequent culprits, particularly when petechiae appear with a fever.
Viral infections
- Mononucleosis: Caused by the Epstein-Barr virus, this condition can cause petechiae, often accompanied by fatigue, sore throat, and swollen lymph nodes.
- Cytomegalovirus (CMV): A common virus that can cause a range of symptoms, including petechiae, especially in newborns.
- Dengue fever: A mosquito-borne virus that can lead to hemorrhagic fever, for which petechiae is a hallmark symptom.
Bacterial infections
- Meningococcemia: Caused by Neisseria meningitidis, this is a severe and life-threatening bloodstream infection that can lead to rapidly spreading petechiae and requires immediate medical intervention.
- Endocarditis: An infection of the heart's lining, endocarditis can cause tiny hemorrhages, including petechiae.
- Strep throat / Scarlet fever: Certain strains of Streptococcus pyogenes can cause scarlet fever, which often presents with a characteristic red rash and petechiae.
- Rocky Mountain Spotted Fever: A tick-borne disease that can cause petechiae, often starting on the wrists and ankles and spreading inward.
Inflammatory and autoimmune conditions
Inflammation of blood vessels is another significant category of causes.
Vasculitis
Vasculitis is a condition where the body's immune system attacks blood vessels, causing them to become inflamed and leak blood. This can cause palpable petechiae, which feel like small bumps under the skin. A specific type is Henoch-Schönlein purpura (HSP), a form of vasculitis affecting children that often follows an upper respiratory infection.
Other autoimmune disorders
- Systemic Lupus Erythematosus (SLE): An autoimmune disease that can affect multiple organs, including the skin, and sometimes cause vasculitis and petechiae.
Nutritional deficiencies and medications
Deficiencies in certain vitamins can impact the strength of blood vessels, while some medications can interfere with platelet function.
Nutritional deficiencies
- Scurvy (Vitamin C Deficiency): Vitamin C is vital for collagen production, which strengthens blood vessel walls. A deficiency can make capillaries fragile and lead to petechiae.
- Vitamin K Deficiency: Vitamin K is necessary for producing several key clotting factors. A deficiency can cause bleeding problems and petechiae.
Medication side effects
Certain medications can either lower platelet counts or interfere with clotting. Examples include NSAIDs like ibuprofen, some antibiotics like penicillin, and drugs used for heart conditions or chemotherapy.
Differential diagnosis: a comparison
| Feature | Thrombocytopenia (e.g., ITP, Leukemia) | Vasculitis (e.g., HSP, SLE) | Severe Infection (e.g., Meningococcemia) |
|---|---|---|---|
| Mechanism | Low platelet count leads to poor clotting. | Inflammation and damage to blood vessel walls. | Systemic infection and toxin release. |
| Skin appearance | Flat, non-palpable petechiae and purpura. | Petechiae that are often palpable (raised). | Rapidly spreading petechiae, often with fever. |
| Associated symptoms | Easy bruising, nosebleeds, bleeding gums. | Joint pain, abdominal pain, kidney issues. | High fever, stiff neck, confusion, shock. |
| Urgency | Can be a medical emergency if platelet count is very low. | Varies depending on severity and organ involvement. | Requires immediate medical attention. |
When to seek medical attention
While some cases of petechiae are benign, the presence of these spots, especially if they spread rapidly, are accompanied by a fever, or other serious symptoms, warrants prompt medical evaluation. A doctor will typically run blood tests, such as a complete blood count (CBC), to check platelet levels and other indicators. Further diagnostic tests may be needed to pinpoint the underlying cause.
Conclusion
From relatively harmless straining to serious systemic diseases, the reasons behind petechiae are diverse. Because petechiae can sometimes signal a medical emergency, particularly when it appears suddenly with other symptoms like fever or confusion, it is important not to dismiss this sign. A medical professional can accurately determine what underlying conditions cause petechiae in your specific situation and recommend the appropriate course of action. For more detailed medical information, consult the StatPearls overview of Petechiae.
