Basic Dermatology Practice Questions

Q: Pyoderma gangrenosum is commonly associated with which of the following conditions?

Ulcerative colitis. **Explanation:** **Pyoderma Gangrenosum (PG)** is a rare, non-infectious neutrophilic dermatosis characterized by rapidly progressing, painful skin ulcers with undermined, violaceous borders. It is classically associated with systemic inflammatory conditions. **Why Ulcerative Colitis (UC) is the correct answer:** While PG is associated with both types of Inflammatory Bowel Disease (IBD), it is significantly more common in **Ulcerative Colitis** (occurring in approximately 5–12% of patients) than in Crohn’s disease (1–2%). The pathogenesis involves neutrophilic dysfunction and a heightened inflammatory response. Notably, the clinical course of PG does not always correlate with the activity of the underlying bowel disease. **Analysis of Incorrect Options:** * **A. Crohn's disease:** Although PG is associated with Crohn’s, UC remains the most frequent systemic association. In Crohn's, skin lesions are more likely to be "metastatic Crohn's" or perianal fistulas. * **B. Diverticulosis:** This is a structural abnormality of the colon wall and lacks the systemic immunological/neutrophilic triggers required to manifest PG. * **C. Colon cancer:** While PG can be a paraneoplastic manifestation of **hematologic malignancies** (like AML or IgA Monoclonal Gammopathy), it is not typically associated with solid organ tumors like colon cancer. **NEET-PG High-Yield Pearls:** 1. **Pathergy Phenomenon:** PG often exhibits pathergy, where minor trauma (like a needle prick or surgery) triggers new lesions or worsens existing ones. 2. **Morphology:** Look for the "violaceous (purple) undermined border" and "cribriform scarring" upon healing. 3. **Treatment:** The mainstay of treatment is **systemic corticosteroids** or Cyclosporine; surgical debridement is contraindicated due to pathergy. 4. **Other Associations:** Rheumatoid arthritis and Myelodysplastic Syndrome (MDS).

Q: Fox-Fordyce spots represent which of the following?

Apocrine sweat glands. **Explanation:** **Fox-Fordyce disease** (also known as apocrine miliaria) is a chronic inflammatory disorder caused by the **obstruction of the apocrine sweat gland ducts**. The correct answer is **D**. The condition occurs when a keratinous plug blocks the infundibulum of the hair follicle, leading to the rupture of the apocrine duct. This causes sweat to leak into the surrounding dermis, resulting in intense pruritus and the characteristic clinical appearance of multiple, small, firm, skin-colored to yellowish papules. **Analysis of Options:** * **A & B (Pilosebaceous/Sebaceous glands):** While Fox-Fordyce disease involves the hair follicle unit, it specifically affects the apocrine component. Note: **Fordyce spots** (without the "Fox") are ectopic sebaceous glands found on the lips or oral mucosa; these are distinct from Fox-Fordyce disease. * **C (Eccrine sweat glands):** Obstruction of eccrine glands leads to **Miliaria** (rubra, crystallina, or profunda), not Fox-Fordyce disease. **Clinical Pearls for NEET-PG:** * **Demographics:** Predominantly affects young women (ages 13–35). * **Distribution:** Occurs in "apocrine-rich" areas—most commonly the **axilla**, followed by the anogenital region and the areola. * **Key Symptom:** Severe, paroxysmal **itching**, which often worsens with emotional stress or heat (stimuli that trigger apocrine secretion). * **Histopathology:** Characterized by "spongiosis" of the follicular infundibulum and the presence of a keratotic plug. * **Treatment:** First-line treatments include topical retinoids and topical steroids; oral contraceptives may help some patients.

Q: What is true about lichen planus?

All of the above. **Explanation:** Lichen Planus (LP) is a chronic inflammatory dermatosis characterized by the **"6 Ps"**: Planar, Purple, Polygonal, Pruritic, Papules, and Plaques. The histopathology of LP is classic and frequently tested in NEET-PG. **Why "All of the Above" is correct:** The hallmark of LP is an interface dermatitis where T-cells attack the dermo-epidermal junction. * **Basal cell degeneration (Option A):** This is the primary event. Liquefactive degeneration (hydropic degeneration) of the basal layer occurs due to the T-cell mediated attack on keratinocytes. * **Colloid bodies (Option B):** Also known as **Civatte bodies** or Cytoid bodies, these are shrunken, eosinophilic, apoptotic keratinocytes found in the lower epidermis and papillary dermis. They represent the end result of basal cell damage. * **Epidermal hyperplasia (Option C):** In response to chronic inflammation, the epidermis thickens. This manifests as irregular acanthosis, often described as a **"Saw-tooth" appearance** of the rete ridges. **High-Yield Clinical Pearls for NEET-PG:** * **Wickham Striae:** White reticular lines on the surface of papules caused by focal **wedge-shaped hypergranulosis**. * **Max-Joseph Spaces:** Small clefts between the epidermis and dermis due to extensive basal cell damage. * **Direct Immunofluorescence (DIF):** Characterized by **shaggy linear deposits of Fibrinogen** along the basement membrane zone. * **Koebner Phenomenon:** Development of lesions at sites of trauma (also seen in Psoriasis and Vitiligo). * **Associations:** Strongly associated with **Hepatitis C infection**.

Q: Bull's eye lesions are clinically seen in which of the following conditions?

Erythema multiforme. **Explanation:** **Erythema Multiforme (EM)** is the correct answer because it is the classic clinical condition associated with **"Bull’s eye"** or **"Target" lesions**. These lesions are pathognomonic and typically consist of three concentric zones: 1. **A central dusky/dark area:** Often showing a blister or crust. 2. **A pale edematous ring:** Surrounding the center. 3. **A peripheral erythematous halo:** Representing the outer border. The underlying medical concept involves a **Type IV hypersensitivity reaction**, most commonly triggered by infections (especially **Herpes Simplex Virus**) or certain medications (like sulfonamides or NSAIDs). The immune system attacks the keratinocytes, leading to the characteristic concentric morphology. **Analysis of Incorrect Options:** * **Lingually impacted 3rd molar (A):** This is a dental/radiological condition and does not present with cutaneous targetoid lesions. * **Taurodontism (C):** This is a dental anomaly where the body of the tooth is enlarged and the roots are reduced in size (resembling a bull’s tooth), but it has no clinical correlation with "Bull's eye" skin lesions. **High-Yield Clinical Pearls for NEET-PG:** * **Distribution:** EM lesions are typically symmetrical and favor the **acral surfaces** (palms, soles, and extensor surfaces of limbs). * **EM Minor vs. Major:** EM Minor involves minimal mucosal involvement, while EM Major involves at least two mucosal surfaces (oral, ocular, or genital). * **Differential Diagnosis:** Targetoid lesions can also be seen in **Stevens-Johnson Syndrome (SJS)**, but in SJS, they are usually "atypical" (two zones instead of three) and more widespread on the trunk. * **Commonest Trigger:** HSV-1 is the most frequent cause of recurrent EM.

Q: Which of the following conditions is characterized by a 'bull's eye' type of radiologic feature?

Lingual impaction of 3rd molar. **Explanation:** The **'bull’s eye' appearance** in dental radiology is a classic sign of a **lingually impacted mandibular third molar**. When a lower third molar is displaced towards the lingual plate, its long axis becomes parallel to the X-ray beam. This projection causes the crown and the root to overlap, creating a radio-opaque circular image with a central radiolucency (representing the pulp canal), mimicking a target or bull’s eye. **Analysis of Options:** * **Lingual impaction of 3rd molar (Correct):** As described, the radiographic foreshortening and overlap of the tooth structures create the characteristic targetoid appearance on a periapical or panoramic radiograph. * **Erythema Multiforme (Incorrect):** While Erythema Multiforme is famous for **'target' or 'bull’s eye' lesions**, these are **clinical skin findings** (concentric erythematous rings), not radiologic features. In a Dermatology or Oral Medicine context, this is a common distractor. * **Ameloblastoma (Incorrect):** This is a benign but aggressive odontogenic tumor. Its classic radiologic appearance is described as **'soap bubble'** or **'honeycomb'** multilocular radiolucency, not a bull’s eye. **High-Yield Clinical Pearls for NEET-PG:** * **Target Lesions (Clinical):** Erythema Multiforme, Stevens-Johnson Syndrome (SJS), and sometimes Fixed Drug Eruptions. * **Target Lesions (Radiological):** Apart from lingual impaction, a 'target' sign on ultrasound can indicate **Intussusception** (Gastrointestinal). * **Buccal vs. Lingual Impaction:** If the impacted tooth appears shifted in the same direction as the tube (SLOB rule), it is lingual; if it appears as a 'bull's eye', it confirms the specific orientation towards the lingual plate.

Q: Which of the following conditions is associated with a defect in DNA repair mechanisms?

Xeroderma pigmentosum. **Explanation:** **Xeroderma Pigmentosum (XP)** is the correct answer because it is a rare autosomal recessive disorder characterized by a fundamental defect in **Nucleotide Excision Repair (NER)**. In healthy individuals, the NER pathway repairs DNA damage (specifically pyrimidine dimers) caused by ultraviolet (UV) radiation. In XP patients, this mechanism fails, leading to extreme photosensitivity, premature skin aging, and a 10,000-fold increased risk of developing skin cancers (BCC, SCC, and Melanoma) at a very young age. **Analysis of Incorrect Options:** * **Ichthyosis:** This refers to a group of genetic skin disorders characterized by dry, thickened, and "fish-like" scaly skin. The defect usually lies in keratinization or skin barrier proteins (e.g., **Filaggrin** in Ichthyosis vulgaris or **Transglutaminase-1** in Lamellar ichthyosis), not DNA repair. * **Mosaicism:** This is a genetic phenomenon where an individual has two or more genetically different cell lines derived from a single zygote. It is caused by post-zygotic mutations (e.g., McCune-Albright syndrome or Segmental Vitiligo) rather than a generalized defect in DNA repair machinery. **High-Yield Clinical Pearls for NEET-PG:** * **Inheritance:** Autosomal Recessive. * **Earliest Sign:** Severe "sunburn" after minimal exposure and prominent **freckling** (ephelides) before age 2. * **Associated Features:** Progressive neurological degeneration (in 20-30% of cases, known as **De Sanctis-Cacchione syndrome**) and ocular abnormalities like photophobia and corneal clouding. * **Diagnosis:** Clinically suspected; confirmed by functional assays for DNA repair or genetic testing. * **Management:** Strict UV protection is the mainstay of treatment.

Q: All are true about lichen planus except:

Not associated with oral ulcer. **Explanation:** Lichen Planus (LP) is a chronic inflammatory condition affecting the skin and mucous membranes. The correct answer is **Option A** because Lichen Planus is frequently associated with oral involvement (seen in up to 50% of patients). **Oral Lichen Planus** can present as reticulate (white lacy patterns), atrophic, or **erosive/ulcerative** lesions. Ulcerative oral LP is a well-recognized clinical variant and carries a small risk of malignant transformation into squamous cell carcinoma. **Analysis of other options:** * **Option B: Wickham’s Striae:** These are characteristic fine, white, lacy lines found on the surface of the papules or oral lesions, caused by focal thickening of the granular layer (orthokeratosis). * **Option C: Colloid Bodies:** Also known as **Civatte bodies** or Cytoid bodies, these are found on histology. They represent apoptotic keratinocytes in the lower epidermis/basal layer and are a hallmark of the interface dermatitis seen in LP. * **Option D: 5 'P's:** This is the classic clinical mnemonic for LP: **P**lanar (flat-topped), **P**urple (violaceous), **P**olygonal, **P**ruritic, and **P**apules. **High-Yield Clinical Pearls for NEET-PG:** 1. **Koebner Phenomenon:** Development of lesions along the site of trauma (also seen in Psoriasis and Vitiligo). 2. **Histology Triad:** Hyperkeratosis (without parakeratosis), "Saw-tooth" appearance of rete ridges, and a band-like lymphocytic infiltrate at the dermo-epidermal junction. 3. **Max-Joseph Spaces:** Small areas of separation between the epidermis and dermis due to basal cell degeneration. 4. **Association:** Often associated with **Hepatitis C** infection. 5. **Treatment:** Topical corticosteroids are the first-line treatment.

Q: Which of the following drugs is used in generalized lichen planus?

Both Dapsone and Systemic steroids. **Explanation:** Lichen Planus (LP) is a chronic inflammatory, T-cell mediated autoimmune condition characterized by the "6 Ps": Planar, Purple, Polygonal, Pruritic, Papules, and Plaques. While localized LP is typically managed with topical corticosteroids, **generalized or eruptive lichen planus** requires systemic intervention to control the widespread inflammation and prevent post-inflammatory hyperpigmentation. * **Systemic Steroids (Option A):** These are the first-line systemic treatment for generalized LP. They work by rapidly suppressing the T-cell mediated immune response, reducing itching, and halting the progression of new lesions. * **Dapsone (Option B):** This is a recognized second-line or adjunctive treatment. It possesses anti-inflammatory and immunomodulatory properties that are particularly effective in treating the bullous variant of LP and generalized cases that are resistant to or require a steroid-sparing agent. Since both drugs are established systemic therapies for extensive disease, **Option C** is the most accurate choice. **Why other options are incorrect:** * **Methotrexate (Option D):** While sometimes used in recalcitrant or erosive mucosal LP, it is not considered a standard first-line systemic therapy for generalized cutaneous LP compared to steroids and Dapsone. **High-Yield Clinical Pearls for NEET-PG:** * **Wickham Striae:** Fine white reticular scales on the surface of papules (due to hypergranulosis). * **Histopathology:** Characterized by "saw-tooth" rete ridges, Civatte bodies (apoptotic keratinocytes), and a band-like lymphocytic infiltrate at the dermo-epidermal junction. * **Koebner Phenomenon:** Development of lesions along the line of trauma (also seen in Psoriasis and Vitiligo). * **Associations:** Strongly associated with **Hepatitis C virus** infection.

Question 1

Pyoderma gangrenosum is commonly associated with which of the following conditions?

Accepted Answer

Ulcerative colitis

Answer

Crohn's disease

Answer

Diverticulosis

Answer

Colon cancer

Question 2

Fox-Fordyce spots represent which of the following?

Accepted Answer

Apocrine sweat glands

Answer

Pilosebaceous glands

Answer

Sebaceous glands

Answer

Eccrine sweat glands

Question 3

Which of the following is NOT included under the diagnostic criteria for Neurofibromatosis type 1?

Accepted Answer

Cafe-au-lait macules

Answer

Optic glioma

Answer

Periungual fibroma

Answer

Sphenoid dysplasia

Question 4

What is true about lichen planus?

Accepted Answer

All of the above

Answer

Basal cell degeneration

Answer

Colloid bodies seen

Answer

Epidermal hyperplasia in chronic cases

Question 5

Bull's eye lesions are clinically seen in which of the following conditions?

Accepted Answer

Erythema multiforme

Answer

Lingually impacted 3rd molar

Answer

Taurodontism

Answer

None of the above

Question 6

Which of the following conditions is characterized by a 'bull's eye' type of radiologic feature?

Accepted Answer

Lingual impaction of 3rd molar

Answer

Erythema multiforme

Answer

Ameloblastoma

Answer

None of the above

Question 7

A patient presented with scarring alopecia, thinned nails, hypopigmented macular lesions over the trunk and oral mucosa. What is the most likely diagnosis?

Accepted Answer

Lichen planus

Answer

Psoriasis

Answer

Leprosy

Answer

Pemphigus

Question 8

Which of the following conditions is associated with a defect in DNA repair mechanisms?

Accepted Answer

Xeroderma pigmentosum

Answer

Icthyosis

Answer

Mosaicism

Answer

None of the above

Question 9

All are true about lichen planus except:

Accepted Answer

Not associated with oral ulcer

Answer

Wickham's striae present

Answer

Colloid body on histology

Answer

Morphology can be represented by 5 'P's

Question 10

Which of the following drugs is used in generalized lichen planus?

Accepted Answer

Both Dapsone and Systemic steroids

Answer

Systemic steroids

Answer

Dapsone

Answer

Methotrexate

Basic Dermatology — MCQs

Basic Dermatology — MCQs

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