Differential Diagnosis for Pruritus without Rash
- Single most likely diagnosis
- Dry skin (xerosis): Given the patient's history of fasting for 17 days, dehydration and dry skin are likely causes of pruritus without rash. The lack of new detergents, soaps, or creams and normal laboratory results support this diagnosis.
- Other Likely diagnoses
- Cholestasis: Although liver function tests (CMP) were normal, cholestasis can cause pruritus without rash. Further evaluation of liver function and bile ducts may be necessary.
- Uremic pruritus: Although the patient's CBC and CMP were normal, kidney function should be further evaluated to rule out uremic pruritus, especially if the patient has a history of kidney disease.
- Thyroid disorders: Although the TSH level was normal, thyroid disorders can cause pruritus without rash. Further evaluation of thyroid function may be necessary.
- Atopic dermatitis: Given the patient's history of seasonal allergies, atopic dermatitis is a possible cause of pruritus without rash.
- Do Not Miss (ddxs that may not be likely, but would be deadly if missed)
- Lymphoma: Lymphoma can cause pruritus without rash, and it is essential to rule out this diagnosis due to its potential severity.
- Leukemia: Leukemia can also cause pruritus without rash, and further evaluation of the patient's blood counts and bone marrow may be necessary.
- Multiple myeloma: Multiple myeloma can cause pruritus without rash, and further evaluation of the patient's blood counts and bone marrow may be necessary.
- Rare diagnoses
- Polycythemia vera: This rare blood disorder can cause pruritus without rash, especially after hot showers.
- Neurological disorders: Certain neurological disorders, such as multiple sclerosis or neuropathy, can cause pruritus without rash.
- Mastocytosis: This rare disorder can cause pruritus without rash, especially if the patient has a history of mast cell disorders.