Dermatopathology Practice Questions

Q: A patient presents with multiple, pearly papules on the face. Biopsy reveals a malignant tumor. Which of the following microscopic features would most likely be observed?

Palisading nuclei. **Explanation:** The clinical presentation of **pearly papules** on the face, often with telangiectasia, is the classic description of **Basal Cell Carcinoma (BCC)**, the most common skin cancer. **Why the correct answer is right:** The hallmark histopathological feature of BCC is the presence of nests or islands of basaloid cells (cells with large, dark nuclei and scant cytoplasm). At the periphery of these nests, the nuclei align themselves in a parallel, fence-like arrangement known as **peripheral palisading**. Additionally, a characteristic "retraction artifact" (clefting) is often seen between the tumor nests and the surrounding stroma. **Why the incorrect options are wrong:** * **A. Cytoplasmic viral inclusions:** These are characteristic of viral infections like Molluscum Contagiosum (Henderson-Patterson bodies) or HPV (koilocytes), not malignant tumors like BCC. * **B. Keratin:** While BCC can occasionally show focal keratinization (Basosquamous variant), **Keratin pearls** are the pathognomonic feature of **Squamous Cell Carcinoma (SCC)**. * **C. Melanin:** While "Pigmented BCC" exists, melanin is the defining feature of **Melanoma**. In a general question about pearly papules, palisading is the more specific diagnostic marker for BCC. **High-Yield NEET-PG Pearls:** * **Most common site:** Upper 2/3rd of the face (above the line joining the earlobe to the angle of the mouth). * **Risk Factor:** Chronic UV exposure; also associated with **Gorlin Syndrome** (PTCH gene mutation). * **Behavior:** Locally invasive ("Rodent ulcer") but rarely metastasizes. * **Treatment of choice:** Surgical excision or Mohs Micrographic Surgery (for high-risk areas).

Q: An epidermal cyst is lined by which type of epithelium?

Stratified squamous epithelium. **Explanation:** An **epidermal cyst** (also known as an epidermal inclusion cyst or sebaceous cyst) is the most common cutaneous cyst. It originates from the follicular infundibulum. 1. **Why the correct answer is right:** The wall of an epidermal cyst is composed of **stratified squamous epithelium** that is identical to the surface epidermis. This lining includes a distinct **granular cell layer**. As the cells mature and shed into the cyst cavity, they form laminated layers of **keratin**, which constitutes the "cheesy" white material found inside. 2. **Why the incorrect options are wrong:** * **Transitional epithelium:** Found in the urinary tract (urothelium); it allows for stretching. It is not found in cutaneous cysts. * **Columnar epithelium:** Typically lines the gastrointestinal tract or respiratory tract. While found in some developmental cysts (like bronchogenic cysts), it does not line epidermal cysts. * **Cuboidal epithelium:** Found in glandular ducts or the thyroid. It is not a feature of true epidermal cysts. **High-Yield Clinical Pearls for NEET-PG:** * **Punctum:** A characteristic central pore or "opening" is often visible on the surface, representing the plugged follicle. * **Histology Tip:** The presence of a **granular layer** distinguishes an epidermal cyst from a **pilar cyst** (trichilemmal cyst), which lacks a granular layer and undergoes "abrupt keratinization." * **Gardner Syndrome:** Multiple epidermal cysts, especially in unusual locations (like the face or scalp), are a clinical marker for Gardner Syndrome (associated with familial adenomatous polyposis). * **Rupture:** If the cyst wall ruptures, the keratin acts as an irritant, leading to a painful foreign-body giant cell reaction (pseudoinflammation).

Question 1

A 74-year-old woman has noted increasing size and number of darker brown patches on the dorsum of each hand for the past 15 years. They do not change with sun exposure, are nonpruritic, and non-tender. On examination, these 0.5- to 1-cm lightly pigmented lesions are flat. Which of the following is the most likely microscopic finding in these lesions?

Accepted Answer

Basal melanocytic hyperplasia

Answer

Dermal nevus cells

Answer

Loss of melanin in surrounding skin

Answer

Mast cell proliferation

Question 2

Which mutation is seen in malignant melanoma?

Accepted Answer

CDKN2A

Answer

N-MYC

Answer

RB gene

Answer

p53

Question 3

A patient presents with multiple, pearly papules on the face. Biopsy reveals a malignant tumor. Which of the following microscopic features would most likely be observed?

Accepted Answer

Palisading nuclei

Answer

Cytoplasmic viral inclusions

Answer

Keratin

Answer

Melanin

Question 4

A 60-year-old diabetic female presented with a burning sensation aggravated by spicy food. Intraoral examination revealed multiple periodontal abscesses and a keratotic area in a lace pattern with occasional erosive areas within the lace pattern. What histological feature would be expected?

Accepted Answer

Saw-tooth rete ridges

Answer

Elongated rete ridges

Answer

Flattened rete ridges

Answer

Bulbous rete ridges

Question 5

An epidermal cyst is lined by which type of epithelium?

Accepted Answer

Stratified squamous epithelium

Answer

Transitional epithelium

Answer

Columnar epithelium

Answer

Cuboidal epithelium

Dermatopathology — MCQs

Dermatopathology — MCQs

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