Dermatopathology Practice Questions

Q: What is the term for a swollen degenerating epithelial cell that results from acantholysis?

Tzanck cell. ### Explanation **Correct Answer: B. Tzanck cell** **Mechanism and Concept:** A **Tzanck cell** is a rounded, degenerating keratinocyte found in the epidermis. It results from **acantholysis**, a process where the intercellular bridges (desmosomes) between squamous epithelial cells are lost [1]. When these connections break, the cells lose their characteristic polygonal shape, detach from one another, and become rounded or "swollen." Cytologically, these cells often exhibit an enlarged nucleus, perinuclear halo, and condensed peripheral cytoplasm. This is a hallmark finding in **Pemphigus vulgaris** and viral infections like **Herpes Simplex (HSV)** and **Varicella-Zoster (VZV)** [1]. **Analysis of Incorrect Options:** * **A. Anitschow cell:** These are "caterpillar cells" (modified macrophages) seen in the heart during **Acute Rheumatic Fever** (Aschoff bodies), not epithelial cells. * **C. Ghost cell:** These are dead cells that retain their cellular outline but have lost their nucleus (karyolysis). They are typically seen in **Coagulative Necrosis** or specific tumors like Pilomatricoma and Craniopharyngioma. * **D. Prickle cell:** This is a normal anatomical term for cells in the *Stratum Spinosum* layer of the skin, named for the "prickly" appearance of their intact desmosomes. They are not degenerating or acantholytic. **High-Yield NEET-PG Pearls:** * **Tzanck Smear:** A rapid bedside diagnostic test where a blister base is scraped to look for these cells. * **Multinucleation:** In viral infections (HSV/VZV), Tzanck cells characteristically show **multinucleation, nuclear molding, and chromatin margination**. * **Pemphigus vs. Pemphigoid:** Tzanck cells are seen in Pemphigus (intraepidermal/acantholytic) but are **absent** in Bullous Pemphigoid (subepidermal/non-acantholytic) [1]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Skin, pp. 1170-1172.

Q: All of the following are markers of melanoma except?

Cytokeratin-20. **Explanation:** The diagnosis of malignant melanoma relies heavily on Immunohistochemistry (IHC) because it can mimic various carcinomas and sarcomas histologically. **Why Cytokeratin-20 (CK20) is the correct answer:** Melanoma is a tumor of neuroectodermal origin (melanocytes), not epithelial origin. **Cytokeratins** are intermediate filaments found in epithelial cells; therefore, melanoma is characteristically **Cytokeratin negative**. CK20, specifically, is a marker for gastrointestinal carcinomas, transitional cell carcinomas, and Merkel cell carcinoma. Its absence helps rule out epithelial malignancies. **Analysis of Incorrect Options:** * **S-100:** This is the **most sensitive** marker for melanoma. While it lacks specificity (also positive in nerve sheath tumors, Langerhans cells, and cartilage), a negative S-100 almost always rules out melanoma. [1] * **HMB-45:** This is a highly **specific** marker for melanoma. It reacts against gp100, a protein found in stage II melanosomes. It is excellent for confirming the diagnosis but may be negative in desmoplastic variants. * **Vimentin:** As melanocytes are derived from the neural crest, they express vimentin (an intermediate filament of mesenchymal cells). Almost all melanomas are Vimentin positive. **High-Yield Clinical Pearls for NEET-PG:** * **Melan-A (MART-1):** Another highly specific and sensitive marker frequently used alongside HMB-45. * **SOX10:** A nuclear marker that is gaining popularity for its high sensitivity in both conventional and desmoplastic melanomas. * **The "Melanoma IHC Panel":** Typically includes S-100, HMB-45, and Melan-A. * **Rule of Thumb:** Melanoma is **S-100 (+), Vimentin (+), but Cytokeratin (-).** [1] **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Skin, pp. 1150-1153.

Q: Munro's microabscesses are typically seen in which layer of the epidermis?

Stratum corneum. **Explanation:** **Munro’s microabscesses** are a pathognomonic histological feature of Psoriasis. They represent focal collections of **neutrophils** that have migrated from the dermal papillae through the epidermis to reach the **Stratum corneum**. This occurs due to the chemotactic effect of leukotriene B4 and IL-8. * **Why Stratum Corneum is correct:** In Psoriasis, the epidermal turnover time is significantly shortened. Neutrophils trapped within the parakeratotic scales (nucleated cells in the horny layer) of the **stratum corneum** form these microabscesses. * **Stratum granulosum:** This layer is typically **thinned or absent** (hypogranulosis) in Psoriasis, making it an incorrect site for these abscesses. * **Basal layer:** This layer shows increased mitotic activity (hyperplasia) in Psoriasis, but it is not the site of neutrophil accumulation. * **Papillary tips:** While dilated capillaries and edema are seen here, neutrophil collections specifically at the papillary tips are characteristic of **Dermatitis Herpetiformis** (forming "Kogoj-like" patterns or papillary microabscesses), not Munro’s microabscesses. **High-Yield Clinical Pearls for NEET-PG:** 1. **Kogoj’s Pustule:** If neutrophils collect in the **Stratum spinosum** (malpighian layer), they are called **Spongeiform pustules of Kogoj** (commonly seen in Pustular Psoriasis). 2. **Histology Mnemonic (P-S-O-R):** **P**arakeratosis, **S**tratum granulosum decrease, **O**longated rete ridges (regular), **R**educed suprapapillary plate thickness. 3. **Auspitz Sign:** Pinpoint bleeding on scraping a psoriatic plaque occurs due to the rupture of dilated capillaries in the dermal papillae covered by a thin suprapapillary plate.

Q: Histopathological diagram of a lesion shows characteristic intracytoplasmic viral inclusion bodies. Which virus is responsible for these inclusions?

Molluscum contagiosum. ***Molluscum contagiosum*** - **Molluscum contagiosum virus** (a **poxvirus**) produces pathognomonic **intracytoplasmic Henderson-Patterson bodies** (molluscum bodies) that are diagnostic. - These **eosinophilic inclusion bodies** are large, well-defined, and occupy most of the cytoplasm in infected keratinocytes. *Cytomegalovirus (CMV)* - CMV produces characteristic **intranuclear inclusions** called **"owl-eye" inclusions**, not intracytoplasmic bodies. - These inclusions are **basophilic** and surrounded by a clear halo within the nucleus. *Herpes simplex virus (HSV)* - HSV creates **intranuclear Cowdry A inclusions** that are **eosinophilic** and surrounded by a clear halo. - The viral inclusions are located in the **nucleus**, not in the cytoplasm as described. *Human papilloma virus (HPV)* - HPV causes **koilocytic changes** with **perinuclear halos** and nuclear enlargement, not distinct inclusion bodies. - The characteristic finding is **koilocytosis** (hollow cells) rather than intracytoplasmic inclusions.

Q: "Church spire effect" is shown by which of the following conditions?

Verruca vulgaris. The **"Church spire effect"** is a classic histopathological descriptor for **Verruca vulgaris** (the common wart), caused by Human Papillomavirus (HPV) [1]. **1. Why Verruca vulgaris is correct:** In Verruca vulgaris, the epidermis undergoes significant reactive changes. The "church spire" appearance refers to **pointed projections of hyperkeratosis** (thickening of the stratum corneum) and **parakeratosis** (retention of nuclei in the stratum corneum) that sit atop a papillomatous (undulating) epidermis [1]. These sharp, peaked elevations resemble the spires of a church. **2. Why the other options are incorrect:** * **Pemphigus vulgaris:** Characterized by **suprabasal acantholysis** (loss of cell-to-cell adhesion) leading to a "tombstone appearance" of the basal layer and intraepidermal blisters. * **Pemphigus vegetans:** A variant of pemphigus characterized by exuberant granulation tissue and **pseudoepitheliomatous hyperplasia**, but it lacks the peaked, spire-like keratinization. * **Verrucous papillary outgrowth:** This is a general morphological description rather than a specific pathological sign like the "church spire" effect. **3. High-Yield Clinical Pearls for NEET-PG:** * **Koilocytes:** The hallmark of HPV infection; these are squamous cells with shrunken, "raisin-like" nuclei surrounded by a clear halo [1]. * **Other features of Verruca:** Hypergranulosis (thickened granular layer) and inward-bending rete ridges (often called "kissing" rete ridges) [1]. * **Acanthosis:** Diffuse epidermal hyperplasia is always present in verrucous lesions [1]. * **Differential Diagnosis:** Seborrheic keratosis also shows papillomatosis but is distinguished by "horn cysts" and a "stuck-on" clinical appearance. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Skin, pp. 1177-1178.

Question 1

What is the term for a swollen degenerating epithelial cell that results from acantholysis?

Accepted Answer

Tzanck cell

Answer

Anitschow cell

Answer

Ghost cell

Answer

Prickle cell

Question 2

All of the following are markers of melanoma except?

Accepted Answer

Cytokeratin-20

Answer

S-100

Answer

HMB-45

Answer

Vimentin

Question 3

Biopsy from a mole on the foot shows cytologic atypia of melanocytes and diffuse epidermal infiltration by anaplastic cells, which are also present in the papillary and reticular dermis. What is the most likely diagnosis?

Accepted Answer

Melanoma, Clark level IV

Answer

Congenital melanocytic nevus

Answer

Dysplastic nevus

Answer

Melanoma, Clark level III

Question 4

Munro's microabscesses are typically seen in which layer of the epidermis?

Accepted Answer

Stratum corneum

Answer

Stratum granulosum

Answer

Basal layer

Answer

Papillary tips

Question 5

Intraepithelial vacuolation with formation of a vesicle or bulla intraepithelially above the basal layer is characteristically seen in which of the following conditions?

Accepted Answer

Pemphigus

Answer

Candida albicans

Answer

Bullous pemphigoid

Answer

Lichen planus

Question 6

Histopathological diagram of a lesion shows characteristic intracytoplasmic viral inclusion bodies. Which virus is responsible for these inclusions?

Accepted Answer

Molluscum contagiosum

Answer

Cytomegalovirus (CMV)

Answer

Herpes simplex virus (HSV)

Answer

Human papilloma virus (HPV)

Question 7

"Church spire effect" is shown by which of the following conditions?

Accepted Answer

Verruca vulgaris

Answer

Pemphigus vulgaris

Answer

Pemphigus vegetans

Answer

Verrucous papillary outgrowth

Question 8

Which cancer is known to develop in chronic ulcers?

Accepted Answer

Squamous cell carcinoma

Answer

Malignant melanoma

Answer

Basal cell carcinoma

Answer

Kaposi sarcoma

Question 9

Examination of a skin lesion demonstrates very abnormal squamous cells with a high nuclear/cytoplasmic ratio and clumped chromatin. These cells form nests within the epidermis that extend to the superficial surface of the epithelium. In some places, nests of these cells have central areas of abnormal keratin formation. The basement membrane is intact and no nests of cells are seen in the dermis. Which of the following terms best describes this lesion?

Accepted Answer

Carcinoma in situ

Answer

Dysplasia

Answer

Invasive carcinoma

Answer

Metaplasia

Question 10

Skin biopsy in leprosy is characterized by which of the following?

Accepted Answer

All of the above

Answer

Periappendageal bacilli

Answer

Periappendageal lymphocytosis

Answer

Perivascular lymphocytosis

Dermatopathology — MCQs

Dermatopathology — MCQs

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