Differential Diagnosis for 71-year-old Female with Facial Swelling and Rash
Single Most Likely Diagnosis
- Dermatomyositis: Given the combination of facial swelling, rash across the body including non-blanching rash on palms, and lack of response to antibiotics, prednisone (though this might be a partial response), famotidine, and cetirizine, dermatomyositis is a strong consideration. The absence of mucous membrane involvement does not rule out this diagnosis.
Other Likely Diagnoses
- Urticarial Vasculitis: The presence of a rash, some of which is non-blanching, suggests vasculitis. The lack of response to antihistamines (cetirizine) and the presence of systemic symptoms (though CRP is normal) could point towards an autoimmune or inflammatory condition like urticarial vasculitis.
- Erythema Multiforme: Although typically involves mucous membranes, some variants might not. The rash and the lack of response to initial treatments could suggest erythema multiforme, especially if triggered by an infection or medication.
- Autoimmune Disorders (e.g., Lupus, Rheumatoid Arthritis): These conditions can present with a wide range of symptoms including rashes and facial swelling. The normal labs do not rule out these diagnoses, as they can be seronegative or have normal inflammatory markers at times.
Do Not Miss Diagnoses
- Wegener's Granulomatosis (Granulomatosis with Polyangiitis): Although less likely given the normal CRP and lack of specific symptoms like sinusitis or renal involvement, this diagnosis is critical not to miss due to its potential for severe morbidity and mortality.
- Malignancy (e.g., Lymphoma, Leukemia): Certain malignancies can present with skin manifestations and systemic symptoms. The age of the patient and the lack of response to standard treatments make it crucial to consider and rule out malignancy.
- Infectious Diseases (e.g., Endocarditis, Lyme Disease): Despite the normal labs and lack of response to antibiotics, it's essential to consider infectious diseases, especially those that can have atypical presentations or require specific diagnostic tests.
Rare Diagnoses
- Relapsing Polychondritis: This condition involves inflammation of cartilage and can present with a variety of symptoms including skin manifestations. It's rare but should be considered in the differential due to the patient's age and the nature of her symptoms.
- Sweet Syndrome (Acute Febrile Neutrophilic Dermatosis): Characterized by fever, neutrophilia, and tender erythematous skin lesions, Sweet syndrome is a rare condition that could be considered, especially if the patient develops fever or other systemic symptoms.
- Sjögren's Syndrome: Although primarily known for its effects on exocrine glands, Sjögren's can also present with skin manifestations and systemic symptoms, making it a rare but possible diagnosis in this case.