Differential Diagnosis for Itching Confined to the Forearms
- Single most likely diagnosis
- Dry skin (xerosis): This is a common condition that can cause itching, especially in areas like the forearms, due to low humidity, harsh soaps, or aging skin. It's often seen in individuals who frequently wash their hands or are exposed to dry environments.
- Other Likely diagnoses
- Atopic dermatitis (eczema): Although it can affect any part of the body, atopic dermatitis often involves the forearms and can cause intense itching. It's associated with allergies and asthma.
- Contact dermatitis: This condition occurs when the skin comes into contact with an irritant or allergen, leading to itching, redness, and sometimes blistering. Common culprits include certain metals (like nickel), latex, or certain plants.
- Insect bites or stings: Reactions to insect bites can cause localized itching and may be confined to the forearms if that's where the bites occurred.
- Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
- Lymphoma: Although rare, certain types of lymphoma, like cutaneous T-cell lymphoma, can present with itching as a primary symptom. It's crucial to consider this in the differential diagnosis due to its severe implications.
- Thyroid disorders: Both hyperthyroidism and hypothyroidism can cause itching, though the mechanism is not fully understood. Itching due to thyroid disorders can sometimes be localized.
- Rare diagnoses
- Polycythemia vera: A rare blood disorder characterized by the overproduction of red blood cells, which can lead to itching, particularly after warm baths or showers. The itching is thought to be due to the release of histamine from basophils.
- Cholestasis: Obstruction of bile flow can cause itching without a rash, though it's typically more generalized. In rare cases, it might be perceived as more localized, including the forearms.