Differential Diagnosis for Armando's Rash
- Single Most Likely Diagnosis + Atopic Dermatitis (Eczema): This is the most likely diagnosis given the itchy and constant nature of the rash, its location on multiple body parts including the thighs, arms, trunk, and between the fingers, and the worsening of symptoms with scratching. The lack of relief from steroid creams used for psoriasis might be due to incorrect usage or potency, but atopic dermatitis typically responds well to topical corticosteroids and moisturizers.
- Other Likely Diagnoses + Contact Dermatitis: Given the distribution of the rash and the fact that it started while Armando was at work, it's possible that he came into contact with an allergen or irritant that caused the rash. The itchy nature and the lack of systemic symptoms support this diagnosis. + Psoriasis: Although Armando tried his mom's steroid cream for psoriasis without relief, psoriasis can present in various forms, including guttate psoriasis, which might not respond as well to topical steroids. The presence of the rash on the trunk, arms, and legs, and the fact that it's constant and itchy, could suggest psoriasis, especially if there's a family history. + Scabies: Given the itchy nature of the rash, especially in the interdigital areas and on the penis, scabies should be considered, particularly if Armando has had close contact with someone who might be infected.
- Do Not Miss Diagnoses + Syphilis: Although Armando denies any penile discharge, fevers, or pain, and has only had one female partner in the last year, syphilis can present with a rash on the palms and soles and can be associated with minimal to no symptoms in its early stages. Given the potential for serious complications if left untreated, syphilis must be considered. + HIV-Related Dermatologic Conditions: Certain skin conditions, including severe eczema or psoriasis-like rashes, can be associated with HIV infection. Given Armando's age and sexual activity, HIV testing might be warranted, especially if other risk factors are present.
- Rare Diagnoses + Pityriasis Rubra Pilaris: A rare skin disorder characterized by constant itching, palmoplantar keratoderma, and follicular hyperkeratotic papules. It's less likely given the description but could be considered if other diagnoses are ruled out. + Dermatomyositis: An inflammatory disease characterized by skin rash and muscle weakness. The rash can be itchy and is typically found on the face, neck, and arms. It's less likely given the distribution and description of Armando's rash but should be considered if there are any systemic symptoms or muscle weakness.