Petechial/Purpuric Rashes- THE ALGORITHMIC APPROACH 


These rashes can be especially challenging and are

associated with devastating differential diagnoses;

however, an algorithmic approach can help the physician

narrow the diagnosis with confidence (Figure 4,

page 12). Additionally, remembering the etiology of

palpable versus nonpalpable lesions is paramount.

Palpable (raised) purpura occurs in vasculitic diseases

secondary to inflammation or infection. Nonpalpable

purpura presents in thrombocytopenic

conditions (flat, subcutaneous hemorrhages). Patients

with petechiae/purpura with fever or toxicity

require emergent evaluation. If the lesions are

palpable, the differential diagnosis includes meningococcemia,

disseminated gonococcal disease, endocarditis,

RMSF, and Henoch-Schönlein purpura.

Those with petechiae/purpura with fever/toxicity

but with nonpalpable lesions may have purpura

fulminans, disseminated intravascular coagulopathy

(DIC), or TTP. If the patient is afebrile with a petechial

or purpuric rash, the diagnosis may be far

simpler and less ominous. Nontoxic patients with

palpable lesions may have a vasculitis, such as autoimmune

vasculitis; those with nonpalpable lesions

may have idiopathic thrombocytopenic purpura.

While all patients with petechiae require complete

assessment, those with nonpalpable petechiae are

more likely to have thrombocytopenia. 


#Diagnosis #Dermatology #Petechial #Petechiae #Purpural #Purpuric #Rash #Algorithm #Nonpalpable #Differential