American Board of Internal Medicine (ABIM) Certification Practice Exam

What characterizes keratoderma blenorrhagicum?

1. A hyperkeratotic rash on the elbows

2. A hyperkeratotic rash on the soles and palms

3. A macular rash on the trunk

4. A vesicular rash on the face

The correct answer is: A hyperkeratotic rash on the soles and palms

Keratoderma blenorrhagicum is a skin condition characterized by the presence of a hyperkeratotic rash, particularly affecting the palms and soles. This condition is typically associated with reactive arthritis, often occurring in patients with a history of urethritis or other mucosal infections. The hyperkeratosis manifests as thickened patches of skin, often with a well-defined border, which can become hyperpigmented over time. The prominence of the rash on the palms and soles is a key distinguishing feature of keratoderma blenorrhagicum. Unlike other skin conditions that may display hyperkeratosis in different areas, such as the elbows or trunk, keratoderma blenorrhagicum specifically targets the areas that experience more friction or pressure, thereby providing a unique clinical profile that helps in diagnosis. Other rashes described in the incorrect options do not align with the presentation of keratoderma blenorrhagicum, which reinforces the understanding of its specific characteristics and its association with systemic conditions.