A patient presents with foreign body sensation in eye and swollen knee joint after a leisure trip. Which of the following is the most probable diagnosis?
**Core Concept**
The patient's symptoms suggest a systemic condition that involves both the ocular and musculoskeletal systems. The foreign body sensation in the eye and swollen knee joint could be indicative of an autoimmune response, which is often seen in conditions like rheumatoid arthritis (RA) or systemic lupus erythematosus (SLE). However, the sudden onset of symptoms and the specific eye involvement make another condition more likely.
**Why the Correct Answer is Right**
The correct answer is related to the formation of antineutrophil cytoplasmic antibodies (ANCA), which are associated with vasculitides, particularly granulomatosis with polyangiitis (GPA) and eosinophilic granulomatosis with polyangiitis (EGPA). GPA is characterized by the presence of c-ANCA (PR3-ANCA) and is known to cause eye symptoms, such as uveitis and scleritis, due to inflammation of the blood vessels in the eyes. The swollen knee joint could be due to inflammation of the synovial membrane, a common feature of GPA.
**Why Each Wrong Option is Incorrect**
**Option A:** While rheumatoid arthritis (RA) can cause eye symptoms, such as dry eye and episcleritis, it is less likely to cause a swollen knee joint as a primary symptom. RA typically causes symmetrical joint involvement and is more common in women.
**Option B:** Systemic lupus erythematosus (SLE) can cause a wide range of symptoms, including eye and joint involvement. However, the combination of foreign body sensation in the eye and swollen knee joint is less typical for SLE.
**Option C:** This option is missing, so we cannot provide an explanation.
**Clinical Pearl / High-Yield Fact**
When considering a diagnosis of GPA, it's essential to remember that the presence of c-ANCA (PR3-ANCA) is a key diagnostic criterion. Additionally, the condition often involves the upper respiratory tract, with symptoms such as sinusitis and nasal discharge.
**Correct Answer:** C.