Differential Diagnosis for Plaque Psoriasis

• Single most likely diagnosis
  • Plaque psoriasis: This is the most likely diagnosis given the presentation of plaque psoriasis, as it is the most common form of psoriasis, characterized by raised, red patches covered with a silvery white buildup of dead skin cells.
• Other Likely diagnoses
  • Seborrheic dermatitis: This condition can present similarly to plaque psoriasis, with a red, itchy rash, but it typically affects the scalp, face, and ears, and has a greasier scale.
  • Nummular dermatitis: Also known as discoid eczema, this condition presents with coin-shaped patches of dry, itchy skin, which can resemble plaque psoriasis.
  • Pityriasis rubra pilaris: A rare skin disorder that causes constant inflammation and scaling (exfoliation) of the skin, which can be mistaken for plaque psoriasis.
• Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
  • Cutaneous T-cell lymphoma (Mycosis fungoides): A rare type of skin cancer that can mimic various skin conditions, including plaque psoriasis, and requires early diagnosis and treatment.
  • Syphilis: In its secondary stage, syphilis can cause a rash that may resemble plaque psoriasis, and if left untreated, can lead to serious complications.
• Rare diagnoses
  • Parapsoriasis: A group of rare skin disorders that can present with scaly, red patches, similar to plaque psoriasis.
  • Lichen planus: An inflammatory condition that affects the skin and mucous membranes, and can present with purplish, itchy, flat bumps, which can be mistaken for plaque psoriasis in some cases.
  • Psoriasiform drug eruption: A rare skin reaction to certain medications, which can cause a psoriasis-like rash.