What classic triad of symptoms is associated with Acute Interstitial Nephritis (AIN)?

The classic triad of symptoms associated with Acute Interstitial Nephritis (AIN) includes fever, rash, and eosinophiluria, making this the correct answer.

Fever is often present due to the inflammatory response triggered by the underlying cause of AIN, such as drug reactions, infections, or autoimmune conditions. A skin rash may develop as a result of hypersensitivity reactions, which are common in cases where medications or allergic factors are the cause of AIN. Eosinophiluria is a key laboratory finding; the presence of eosinophils in the urine indicates an allergic or inflammatory process affecting the renal interstitium.

Other answer choices, while related to different renal or systemic conditions, do not pertain specifically to AIN. Flank pain and hematuria could be more indicative of renal calculi or pyelonephritis, while chest pain, dyspnea, and cough relate primarily to respiratory or cardiovascular issues. Lastly, edema, hypertension, and proteinuria are more characteristic of nephrotic syndrome or chronic kidney conditions rather than the acute inflammatory process seen in AIN. Thus, the first choice accurately encapsulates the defining features of Acute Interstitial Nephritis.