Differential Diagnosis for a Rash with Small Red Dots
The description of a rash with small red dots all over, some of which are slightly raised, can be indicative of several conditions. Here's a categorized differential diagnosis:
Single Most Likely Diagnosis
- Petechiae or Purpura: These are small, pinpoint spots that occur due to minor hemorrhages from broken capillary blood vessels. They can appear as small red dots and are often seen in conditions like thrombocytopenia or after intense coughing. The slightly raised appearance could be due to inflammation or the body's response to the hemorrhage.
Other Likely Diagnoses
- Folliculitis: An inflammation of the hair follicles, which can cause small, red, raised bumps, especially if the rash is concentrated in areas with high hair density.
- Pityriasis Rosea: Although it typically starts with a herald patch, the subsequent rash can appear as small, raised red dots, often distributed in a Christmas tree pattern on the back.
- Erythema Multiforme: A skin condition characterized by target lesions, but in its early stages, it can appear as small red dots. It's often associated with infections or medication reactions.
Do Not Miss Diagnoses
- Meningococcemia: A severe infection caused by Neisseria meningitidis, which can present with a petechial or purpuric rash. This condition is life-threatening and requires immediate medical attention.
- Rocky Mountain Spotted Fever (RMSF): A tick-borne illness that can cause a rash, often starting as small red dots that may become raised. RMSF is serious and can be fatal if not treated promptly.
- Disseminated Gonococcal Infection: A condition where gonorrhea infection spreads through the bloodstream, potentially causing a rash with small red or pink spots, some of which may be slightly raised.
Rare Diagnoses
- Leptinosis: Caused by the bacterium Leptospira, this infection can lead to a rash among other symptoms, though it's less common.
- Secondary Syphilis: Can cause a wide variety of rashes, including small red dots, though this is less typical and usually accompanied by other symptoms.
- Viral Exanthems: Certain viral infections can cause rashes that might fit the description, such as enterovirus or parvovirus B19 infections, though the presentation can vary widely.
Each of these conditions has distinct features and associated symptoms that can help narrow down the diagnosis. A thorough medical history, physical examination, and sometimes laboratory tests are necessary to determine the exact cause of the rash.