Differential Diagnosis for Maculopapular Rashes

Single Most Likely Diagnosis

• Viral Exanthem: This is the most common cause of maculopapular rashes, especially in children and young adults. Viruses such as enteroviruses, adenoviruses, and parvovirus B19 can cause widespread rashes that cover the face, trunk, extremities, and sometimes palms and soles.

Other Likely Diagnoses

• Drug Reaction: Many medications can cause maculopapular rashes, including antibiotics, anticonvulsants, and NSAIDs. The rash can appear anywhere on the body, including the palms and soles.
• Allergic Contact Dermatitis: This is a type of skin inflammation caused by contact with an allergen or irritant. The rash can be maculopapular and can appear on any exposed area, including the face, trunk, extremities, and palms/soles.
• Insect Bite Reaction: Insect bites can cause maculopapular rashes, especially if the person has a sensitivity or allergy to the insect's saliva.

Do Not Miss Diagnoses

• Secondary Syphilis: This is a critical diagnosis to consider, as syphilis can cause a maculopapular rash on the palms and soles, which is a distinctive feature. If left untreated, syphilis can lead to serious complications.
• Rocky Mountain Spotted Fever (RMSF): This is a tick-borne illness that can cause a maculopapular rash, which can appear on the palms and soles. RMSF can be life-threatening if not treated promptly.
• Kawasaki Disease: This is an acute febrile illness that can cause a maculopapular rash, as well as other symptoms such as fever, conjunctivitis, and lymphadenopathy. If left untreated, Kawasaki disease can lead to serious cardiac complications.

Rare Diagnoses

• Pityriasis Rosea: This is a rare skin condition that causes a maculopapular rash, often with a distinctive "herald patch" on the trunk. The rash can appear on the face, trunk, and extremities, but rarely on the palms and soles.
• Erythema Infectiosum: This is a rare viral illness that causes a maculopapular rash, often with a "slapped cheek" appearance on the face. The rash can appear on the trunk, extremities, and rarely on the palms and soles.
• Leptospirosis: This is a rare bacterial illness that can cause a maculopapular rash, as well as other symptoms such as fever, headache, and muscle aches. The rash can appear on the face, trunk, and extremities, but rarely on the palms and soles.