Differential Diagnosis
The patient presents with a rash that appeared 2 weeks following a viral illness, characterized by flesh-colored, raised, pruritic, and painful bumps on the bilateral hands, tops and palmar aspect, left elbow, and top of left foot, accompanied by stiffness, particularly with clenching of hands. Based on these symptoms, the differential diagnosis can be categorized as follows:
- Single most likely diagnosis
- Guttate Psoriasis: This condition is often triggered by a viral infection, such as streptococcal pharyngitis, and can present with small, raised, flesh-colored bumps (papules) that are pruritic. The distribution on the hands, elbows, and feet, along with the history of a preceding viral illness, supports this diagnosis.
- Other Likely diagnoses
- Pityriasis Rosea: Although typically presenting on the trunk, pityriasis rosea can occasionally appear on the extremities. It is preceded by a viral illness and characterized by a herald patch followed by a secondary eruption of oval, scaly patches. The pruritic nature and the timing post-viral illness make it a consideration.
- Dyshidrotic Eczema (Pompholyx): Characterized by small, itchy blisters on the palms or soles, dyshidrotic eczema could be considered given the palmar involvement and pruritus. However, the absence of vesicles and the specific mention of "flesh-colored raised bumps" makes this less likely.
- Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
- Secondary Syphilis: Although less common, secondary syphilis can present with a rash on the palms and soles, which is a distinctive feature. Given the potential severity of untreated syphilis, this diagnosis should not be missed, despite its lower likelihood.
- Lyme Disease: Early disseminated Lyme disease can cause multiple erythema migrans lesions, which might appear as raised, expanding patches. The history of a viral illness is not typical, but the potential for severe consequences if untreated makes it a "do not miss" diagnosis.
- Rare diagnoses
- Keratoderma Blennorrhagicum: Associated with reactive arthritis, this condition presents with vesiculopustular eruptions on the palms and soles, which can evolve into hyperkeratotic lesions. It's a rare consideration but could fit the description of painful, stiffening lesions on the hands and feet.
- Papulovesicular Acrolocated Eruption: A rare condition characterized by itchy, papulovesicular lesions on the hands and feet, often following a viral infection. The specific distribution and the post-viral onset align with the patient's symptoms, although this is a less common entity.