Differential Diagnosis
The patient's symptoms of limb weakness, difficulty breathing, fever, weight loss, purpuric lesions, and sensory and motor neuropathy suggest a complex and multifaceted condition. Here's a categorized differential diagnosis:
Single most likely diagnosis
- Vasculitis (e.g., Polyarteritis Nodosa or Granulomatosis with Polyangiitis): The combination of limb weakness, purpuric lesions, fever, weight loss, and neuropathy points towards a systemic vasculitis. The improvement in breathing difficulty with an inhaler might suggest an associated asthma-like condition, which can be seen in Churg-Strauss syndrome, a type of vasculitis.
Other Likely diagnoses
- Lymphoma: The presence of fever, weight loss, and neuropathy could suggest a lymphoma, particularly if there's involvement of the nervous system.
- Chronic Inflammatory Demyelinating Polyneuropathy (CIDP): This condition could explain the progressive limb weakness and neuropathy, but it doesn't fully account for the systemic symptoms like fever and purpuric lesions.
- Sarcoidosis: This multisystem disease can cause neuropathy, lung involvement (which might explain the breathing difficulty and response to inhalers), and skin lesions, but the purpuric nature of the lesions is less typical.
Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
- Guillain-Barré Syndrome: Although less likely given the chronic progression and systemic symptoms, Guillain-Barré syndrome is a medical emergency that can cause rapid progression of weakness and respiratory failure.
- Amyotrophic Lateral Sclerosis (ALS): While ALS primarily causes motor symptoms without sensory involvement, some variants can present with sensory symptoms, and the disease is fatal if not recognized and managed appropriately.
Rare diagnoses
- Multifocal Motor Neuropathy: A rare condition causing asymmetric muscle weakness, which could fit some of the patient's symptoms but doesn't account for the systemic features.
- Eosinophilic Granulomatosis with Polyangiitis (Churg-Strauss Syndrome): A rare form of vasculitis that could explain many of the patient's symptoms, including asthma-like symptoms, neuropathy, and purpuric lesions.
- Neurosarcoidosis with systemic involvement: While sarcoidosis is considered above, neurosarcoidosis with extensive systemic involvement is less common and could explain many of the patient's diverse symptoms.