**Core Concept**
Antihistone antibodies are autoantibodies that target histone proteins in the nucleus, particularly histone H1. They are classically associated with drug-induced lupus, where drugs like hydralazine, procainamide, and isoniazid trigger an immune response leading to the formation of these antibodies.

**Why the Correct Answer is Right**
In drug-induced lupus, antihistone antibodies are a hallmark serological finding. These antibodies form when drugs interfere with normal histone structure or function, leading to immune complex formation and activation of the complement system. They are detectable in serum and are often found in patients with drug-induced lupus, especially those on chronic therapy. The presence of antihistone antibodies correlates with clinical features such as arthralgia, rash, and serositis, though they are not specific to lupus.

**Why Each Wrong Option is Incorrect**
Option A: CREST syndrome involves antitopoisomerase I (anti-Scl-70) and anti-centromere antibodies, not antihistone antibodies.
Option B: PAN (polyarteritis nodosa) is characterized by anti-PR3 or anti-MPO antibodies, not antihistone antibodies.
Option D: Intestinal lymphoma is associated with immunoglobulin-based markers and B-cell dysregulation, not antihistone antibodies.

**Clinical Pearl / High-Yield Fact**
Antihistone antibodies are most commonly seen in drug-induced lupus and should prompt evaluation for drug exposure. Their presence can help differentiate drug-induced lupus from systemic lupus erythematosus (SLE), where antihistone antibodies are less frequent and often not diagnostic.

✓ Correct Answer: C. Drug induced Lupus