Okay, let's tackle this question. The patient is a 78-year-old woman with multiple lesions on her face and back. The lesions are described as well-circumscribed, tan to brownish, slightly raised, rough, and 0.5-1.5 cm. The key point is that the clinician can peel away parts of the lesion with a scalpel blade. Hmm.

First, I need to think about skin lesions in elderly patients. Common ones include seborrheic keratosis, actinic keratosis, basal cell carcinoma, and maybe melanoma. But the description here is important. Seborrheic keratoses are often called "barnacles of aging" and are common in older adults. They have a waxy, stuck-on appearance, and the "peeling" with a scalpel blade is a classic sign of seborrheic keratosis. The term for that is the "pencil sign" or "scale sign," where the surface can be scraped off, revealing a smooth layer underneath.

Actinic keratosis is another possibility, but those are usually rough, scaly, and more associated with sun-exposed areas. However, actinic keratoses are considered precancerous and don't typically peel off easily. Basal cell carcinomas are usually pearly or waxy nodules, not the same description. Melanoma would have more irregular features, like asymmetry, notched borders, multiple colors, which isn't mentioned here.

The key here is the clinical sign with the scalpel. Seborrheic keratosis is known for the ability to scrape off the surface. Also, the age and location (face and back) fit. So the answer is likely seborrheic keratosis. Let me check the options again. The correct answer is D, so I need to make sure that D is Seborrheic Keratosis. The other options would be actinic keratosis, basal cell carcinoma, and maybe melanoma. Each of those doesn't have the peeling characteristic. The peeling is a hallmark of seborrheic keratosis, so the answer is D.

**Core Concept**
The question tests recognition of seborrheic keratosis, a benign epidermal tumor common in older adults. Key diagnostic features include the "pencil sign," where the lesion's surface can be scraped off with a scalpel blade due to its waxy, adherent keratin layer.

**Why the Correct Answer is Right**
Seborrheic keratoses are benign, hyperkeratotic lesions with a characteristic "stuck-on" appearance. The ability to "peel away" the surface (pencil sign) occurs because the lesion's outer layer is loosely attached to the underlying epidermis. This is due to acanthotic epidermal proliferation with a compressed, hyperkeratotic stratum corneum. The described tan-brown color and size further align with seborrheic keratosis.

**Why Each Wrong Option is Incorrect**
**Option A:** Actinic keratosis presents as rough, erythematous, or scaly patches, not peelable lesions. It lacks the waxy surface and is considered premalignant.
**Option B:** Basal cell carcinoma (BCC) typically

✓ Correct Answer: D. Seborrheic keratoses