Differential Diagnosis
The patient presents with a rash on her face, muscle aches and pains, especially in her wrists and hands, and a history of Hashimoto thyroiditis. Based on the provided information, the differential diagnosis can be categorized as follows:
Single most likely diagnosis
- A. dermatomyositis: The presence of erythematous, flaky patches on the dorsum of the hands along the knuckles, known as Gottron's sign, is a characteristic feature of dermatomyositis. The patient's symptoms of muscle aches and pains, particularly in the wrists and hands, also support this diagnosis. The association with Hashimoto thyroiditis, an autoimmune condition, further increases the likelihood of an autoimmune disease like dermatomyositis.
Other Likely diagnoses
- E. rheumatoid arthritis: Although the patient's symptoms could be consistent with rheumatoid arthritis, the presence of a characteristic rash and the specific distribution of muscle aches and pains make dermatomyositis more likely. Rheumatoid arthritis is still a possibility, especially given the patient's complaints of wrist and hand pain.
- D. psoriatic arthritis: This condition could be considered due to the presence of a rash and joint pain. However, the description of the rash as erythematous and flaky, without mention of psoriatic plaques, makes this diagnosis less likely.
Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
- B. erysipelas: Although erysipelas is an infection of the upper dermis and superficial lymphatics, typically presenting with well-demarcated, erythematous lesions, it is less likely given the patient's chronic symptoms and the presence of muscle aches. However, it's crucial to consider infectious causes, especially if the patient's condition worsens or does not respond to initial treatment.
- C. fibromyalgia: While fibromyalgia could explain the patient's muscle aches and pains, it does not account for the rash. Fibromyalgia is a diagnosis of exclusion and should be considered if other diagnoses are ruled out.
Rare diagnoses
- Other rare autoimmune or connective tissue diseases could be considered, but they are less likely given the patient's presentation and would require additional diagnostic testing to confirm. Examples might include systemic lupus erythematosus or mixed connective tissue disease, but these would be less likely without additional specific symptoms or findings.