Okay, let's tackle this question. The patient is a 34-year-old woman with bloody nipple discharge, no masses, and normal skin. She's on oral contraceptives. The question is about the most likely lesion found on excisional biopsy.

First, I need to think about the differential diagnoses for bloody nipple discharge. Common causes include ductal papilloma, intraductal carcinoma, fibrocystic changes, or maybe some benign conditions. Since there's no mass or lymphadenopathy, malignancy is less likely, but still possible.

Ductal papilloma is a benign tumor that often presents with bloody discharge. It's the most common cause of spontaneous bloody discharge. Intraductal papilloma is another possibility, but usually associated with a palpable mass. Fibrocystic changes can cause discharge but are more associated with cyclical pain and lumps. Intraductal carcinoma, like Paget's disease, can present with discharge but often has other signs like skin changes or a mass.

The patient uses oral contraceptives, which might influence the type of lesion. However, the key here is the absence of a mass. Ductal papilloma is a small lesion within the duct, so it might not be palpable. The excisional biopsy would show a papillary lesion with fibrovascular cores and epithelial proliferation.

Now, looking at the options (though they're not labeled here), the correct answer is likely ductal papilloma. The other options like fibrocystic changes or intraductal carcinoma would present differently. So the explanation should highlight the typical presentation of ductal papilloma and why other options are less likely.

**Core Concept**
The question assesses the differential diagnosis of bloody nipple discharge in a young woman without palpable mass. The key principle involves recognizing the most common benign lesion associated with this presentation, which is **intraductal papilloma**, characterized by papillary proliferation within a breast duct.

**Why the Correct Answer is Right**
Intraductal papilloma is the most frequent cause of **bloody, unilateral, spontaneous nipple discharge** in women aged 30–50 years. It arises from a single large duct, often near the nipple, and presents with minimal systemic symptoms. Histologically, the lesion shows **cylindrical or papillary projections** with fibrovascular cores lined by cuboidal epithelium. The absence of a palpable mass or skin changes (e.g., peau d’orange) supports a benign etiology. Oral contraceptive use may exacerbate ductal secretions but is not directly causative.

**Why Each Wrong Option is Incorrect**
**Option A:** *Fibrocystic changes* cause non-bloody, milky discharge and are associated with cyclic breast pain and palpable lumps, not isolated bloody discharge.
**Option B:** *Intraductal carcinoma* (e.g., Paget’s disease) typically presents with eczematous nipple changes, fixed mass, or lymphadenopathy, which are absent here.
**Option C:** *Ductal carcinoma in situ* (DCIS) often involves microcalcifications and is linked to mammographic abnormalities, not isolated bloody discharge without a mass.

**Clinical Pearl / High-Yield Fact**
**Remember the “Rule of 1s” for intr

✓ Correct Answer: C. Intraductal papilloma