Differential Diagnosis
- Single most likely diagnosis
- Ehlers-Danlos Syndrome (EDS) or a related disorder: The patient's symptoms of muscle and skin weakness, looseness, and stretchiness, along with a history of suspected immune dysregulation and partial improvement with high-dose steroids, could suggest an underlying connective tissue disorder. EDS is known for its skin hyperextensibility, joint hypermobility, and tissue fragility. The iatrogenic trigger might have exacerbated an underlying condition.
- Other Likely diagnoses
- Dermatomyositis: An inflammatory disease characterized by skin rash and muscle weakness, which can be triggered by various factors including drugs (iatrogenic). The partial response to high-dose steroids supports this diagnosis, as dermatomyositis is known to respond to immunosuppressive therapy.
- Scleroderma (Systemic Sclerosis): This autoimmune disorder can cause skin tightening and thickening, but some forms, like limited systemic sclerosis, might present with skin looseness in certain stages. The immune dysregulation history and response to steroids make it a consideration.
- Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
- Sepsis or Infection: Although less likely given the description, any condition causing significant skin and muscle compromise could potentially lead to infections or sepsis, which are medical emergencies.
- Malignancy (e.g., Dermatologic or Soft Tissue Sarcomas): Certain malignancies can cause rapid changes in skin and muscle, and while less likely, missing a diagnosis of cancer could have severe consequences.
- Rare diagnoses
- Pseudoxanthoma Elasticum (PXE): A genetic disorder affecting connective tissue, leading to skin laxity among other symptoms. It's less likely but could be considered in the differential due to the skin and potential muscle involvement.
- Cutis Laxa: A group of rare disorders characterized by inelastic, hanging skin, which could be acquired or inherited. The iatrogenic trigger might be relevant in the acquired form.