Differential Diagnosis for Pruritus in a 70-year-old Lady

Single most likely diagnosis

• Dry skin (xerosis): This is a common condition in the elderly due to decreased moisture in the skin, which can cause pruritus without any visible skin lesions or rash. The lack of skin findings and the age of the patient make this a highly plausible diagnosis.

Other Likely diagnoses

• Chronic kidney disease: Pruritus is a well-known symptom in patients with chronic kidney disease, particularly in those undergoing dialysis. The mechanism is not fully understood but is thought to be related to the buildup of uremic toxins.
• Hypothyroidism: Some patients with hypothyroidism may experience pruritus, although the exact mechanism is unclear. This condition is more common in women and can occur at any age, including the elderly.
• Iron deficiency anemia: Iron deficiency can cause pruritus, possibly due to the effect of iron deficiency on the skin and nervous system.
• Psychogenic causes: Psychological factors such as anxiety and depression can manifest as pruritus without any skin lesions. Elderly individuals may be more prone to these conditions due to social isolation, loss of loved ones, or chronic illness.

Do Not Miss (ddxs that may not be likely, but would be deadly if missed)

• Hodgkin lymphoma: Although rare, Hodgkin lymphoma can present with pruritus as an initial symptom, often without any other specific findings. Missing this diagnosis could lead to delayed treatment and a poorer prognosis.
• Multiple myeloma: This plasma cell dyscrasia can cause pruritus, among other symptoms like bone pain and anemia. Early detection is crucial for effective management.
• Cholestasis: Obstruction of the bile ducts can lead to the accumulation of bile salts in the skin, causing intense pruritus without rash. This condition requires prompt diagnosis and treatment to prevent liver damage.

Rare diagnoses

• Neurological disorders (e.g., multiple sclerosis, neuropathy): Certain neurological conditions can cause pruritus due to nerve damage or dysfunction. These are less common causes but should be considered if other diagnoses are ruled out.
• Paraneoplastic syndromes: These are rare disorders that are triggered by an altered immune system response to a neoplasm. Pruritus can be a symptom of some paraneoplastic syndromes.
• Aquagenic pruritus: A rare condition characterized by intense pruritus after contact with water, without any visible skin lesions. The cause is unknown, and diagnosis is often one of exclusion.