Petechiae are pinpoint non-blanching spots that measure less than 2 mm in size which affect the skin and mucous membranes. A non-blanching spot is one that does not disappear after brief pressure is applied to the area. Purpura is a non-blanching spot that measures greater than 2 mm. Petechial rashes are a common presentation to the pediatric emergency department (PED). Non-blanching rashes can be a great cause for concern for parents and physicians alike. Therefore, a careful assessment and evaluation must be undertaken to formulate a sensible management plan.
There are many causes of a petechial rash in a child to be considered. Invasive meningococcal disease (IMD) caused by Neisseria meningitidis, is the priority in the differential diagnosis to consider on initial presentation. Consequently, a child with fever and a petechial rash requires urgent and comprehensive assessment. Multiple studies have shown that the rate of IMD has reduced following the introduction of meningococcal vaccines into childhood immunization schedules and that the low prevalence of IMD suggests that most children presenting with a petechial rash have less serious pathologies. However, given its associated morbidity and mortality, it should remain at the forefront of the clinician's mind when assessing the child with pyrexia and petechiae.
Causes can be classified into the following categories:
Hematological and Malignant
Vasculitis and Inflammatory Conditions
Connective Tissue Disorder
One study reported that 2.5% of presentations to the pediatric emergency department were patients with a petechial rash.
Petechial rashes result from areas of hemorrhage into the dermis. Derangements in the normal hemostasis can result in petechiae along with a variety of other clinical findings. The primary pathophysiological causes of petechiae and purpura are thrombocytopenia, platelet dysfunction, disorders of coagulation, and loss of vascular integrity. Some clinical pictures result in petechial lesions from a combination of these mechanisms.
A detailed history and physical examination are paramount for every child presenting with petechiae. Key features in the history include time of onset, anatomical pattern and a detailed chronological account of any other symptoms, e.g., fever, coughing, vomiting, any recent URTI or gastroenteritis, and any sick contacts. A rapidly spreading rash is more concerning for IMD in an unwell child with a fever. A recent viral infection (URTI or gastroenteritis) is common in ITP, HSP, and HUS. Petechiae confined to above the nipple line are associated with bouts of vomiting or coughing. It is also important to ask about any bleeding from mucosal surfaces such as gingival bleeding, epistaxis, melena, among others. As always, vaccination status should be confirmed.
On examination, a complete set of observations and neurological status should be regularly monitored. A full systemic examination should be completed, including cardiac, respiratory, abdominal, otorhinolaryngological, and neurological (if concerns of IMD). The skin should be thoroughly examined from head to toe, and the pattern of rash should be clearly documented. Demarcating areas of petechiae with a skin marker can be helpful for monitoring progression of the rash in clinical practice.
The age of the child can be useful in reaching the most likely diagnosis, for example; a neonate with petechiae could have a NAIT or a TORCH infection, and HSP is more common in the 2 to 5 year age range.
Patterns of concerning symptoms and signs presenting with petechiae include but are not limited to:
Investigations to diagnose the cause of a petechial rash depend on the clinical presentation and can differ from one PED to another. Adhering to the local protocol is advised. In general, investigations will depend on the location of petechiae, associated pyrexia or clinical suspicion for any of the concerning patterns of signs and symptoms. A healthy child with scattered petechiae of obvious causation, e.g., known trauma or petechiae confined to above the nipple line may not require any investigations. At the very least, the healthy child, as described, should be observed for 4 hours before discharge.
Many patients attending the PED with petechial rashes will not require any specific treatment. In fact, if a child remains well after a period of observation, with no spreading of the rash, a normal platelet count and no physical signs or signs of infection on blood tests, they may be discharged home. If IMD is likely, urgent intravenous antibiotics as per local guidelines should be administered, with close observations after admission to the ward. Some patients may be given a dose of antibiotics pre-hospital if high clinical suspicion of IMD is present. If specific diagnoses are made, for example, HSP or ITP, and there is no risk of going home, the child may be discharged with an appointment to return to the appropriate outpatient department and condition specific education. Other conditions will require admission and treatment, for example, urgent referral to oncology inpatient services for a patient with pancytopenia and a likely malignant diagnosis.
Recognizing the wide range of possible diagnoses for a child presenting with petechiae is essential for any clinician working in the PED. Public health campaigns have increased recognition of petechiae, therefore, allaying parents fears and concerns is a key role, in addition to educating them on red flag signs that should prompt return to the PED.