Maculopapular Rash : Diagnosis

• A macule is a flat blemish or discoloration that measures less than 1 cm. 
• A papule is as elevated lesion measuring less than 1 cm. 
• Combining the two terms, a maculopapular rash is as a smooth skin rash or redness covered by elevated bumps
• Due to the presence of inflammation, maculopapular rash appears as reddened or erythematous. The distribution may be concentrated on a certain area of the body or it can be generalized. 
• It may be acute, subacute, or chronic. 
• Acute maculopapular rash lasts less than 4 weeks; 4-8 weeks for subacute; and it is considered chronic if the rash lasts for more than 8 weeks.
• The occurrence of maculopapular rash for children is generally due to viral infection. 
• For the adults, drugs and allergies are often the culprit.

Diagnostic Approach

Pictures and Conditions:

 Maculopapular Rash on the back of a 14 month old girl and probably an exacerbation of Ebstein Barr Virus infection

 Maculopapular rash on HIV patient

 Maculopapular rash in a patient with H1N1 influenza

 maculopapular rash seen in a man with severe diarrhea

 Maculopapular rash after otitis media

Erythematous Maculopapular Rash

Maculopapular Rash image 

Maculopapular Rash on trunk 

Differential Diagnosis

• Maculopapular rash may be mistakenly called macule, papule, patch, nodule, plaque, vesicle, or pustule. 
• To differentiate these skin lesions from each other, here are the pictures of each
  

A patch is like an enlarged macule. It measures more than 1 cm.

Like macule, a papule measures less than 1 cm. However, it is elevated unlike the macule which is flat. An example of a papule is molluscum contagiosum

A nodule is a spherical elevation of the skin measuring more than 1 cm. It becomes a tumor once the size exceeds 2-3 cm

 A plaque measures more than 1.5 cm. The center area is flat and the edges have elevated lesions. An example of a plaque is psoriasis.

 Vesicles (green arrows) and bulla (red arrow) both contain fluid in them. They are rounded and elevated. The difference between the two is the size. Vesicles measure less than 1 cm while bullae are more than 1 cm.

 A pustule is a lesion that contains pus.

 

Reference and notes adapted from

• http://emedicalhub.com/maculopapular-rash/