Basic Dermatology Practice Questions

Q: All of the following are true regarding erythrocyanosis frigida, EXCEPT:

Seen exclusively in alcoholic males. **Explanation:** **Erythrocyanosis frigida** (also known as *erythrocyanosis crurum puellarum frigida*) is a localized vascular disorder caused by an abnormal response to cold. **1. Why Option A is the Correct Answer (The Exception):** The statement is false because the condition is seen **almost exclusively in young women**, particularly those with "heavy" or fat legs. It is not associated with alcoholic males. The pathogenesis involves cold-induced vasospasm of the arterioles followed by secondary dilatation of the capillaries and venules in areas with thick subcutaneous fat. **2. Analysis of Other Options:** * **Option B:** It characteristically involves the **lower third of the leg**, the ankles, and sometimes the posterior aspect of the calves. The affected skin appears dusky, cyanotic, and cold to the touch. * **Option C:** Severe cases can lead to the formation of painful, chronic ulcers known as **Bazin’s ulcers** (Erythema Induratum). While Bazin's disease is traditionally associated with tuberculosis, the term is also used for the ulcerative stage of erythrocyanosis. * **Option D:** Treatment focuses on keeping the limbs warm. However, in severe or refractory cases, **lumbar sympathectomy** may be beneficial to improve peripheral blood flow and promote healing of ulcers. **Clinical Pearls for NEET-PG:** * **Triad of Erythrocyanosis:** Coldness, cyanosis (bluish-red discoloration), and swelling. * **Differential Diagnosis:** Must be distinguished from **Chilblains** (Pernio), which presents as itchy/burning papules on fingers/toes, and **Livedo Reticularis**. * **Key Demographic:** Think "Young females with thick legs in cold climates."

Q: What is the primary function of Langerhans cells?

Antigen presentation. **Explanation:** **Langerhans cells (LCs)** are specialized dendritic cells located primarily in the **Stratum Spinosum** of the epidermis. Their primary function is **Antigen Presentation**. As the skin’s "sentinels," they capture exogenous antigens via their dendrites, process them, and migrate to regional lymph nodes. There, they present these antigens to naive T-cells, initiating an adaptive immune response (specifically Type IV hypersensitivity). **Analysis of Options:** * **Option B (Correct):** LCs are professional antigen-presenting cells (APCs). They express MHC Class II molecules and contain characteristic **Birbeck granules** (tennis-racket shaped), which are involved in endocytosis. * **Option A:** While LCs can internalize particles, their primary physiological role is not systemic clearance (phagocytosis), which is the domain of macrophages/neutrophils. * **Options C & D:** While LCs are involved in the immune milieu of various diseases, they are not specifically defined by an association with autoimmune conditions or chronic infections in a diagnostic sense. **High-Yield Clinical Pearls for NEET-PG:** * **Origin:** Derived from the **Bone Marrow** (monocyte-macrophage lineage). * **Markers:** Positive for **CD1a, S100, and Langerin (CD207)**. * **Electron Microscopy:** Pathognomonic **Birbeck granules** (tennis-racket appearance). * **Clinical Correlation:** **Langerhans Cell Histiocytosis (LCH)** is a proliferative disorder where these cells infiltrate various organs. On imaging, it may present as "punched-out" lytic bone lesions.

Q: Which of the following conditions does not show an isomorphic type of Koebner phenomenon?

Molluscum contagiosum. ### Explanation The **Koebner phenomenon** (isomorphic response) refers to the development of skin lesions characteristic of a pre-existing dermatosis at the site of trauma or injury to previously healthy skin. #### Why Molluscum Contagiosum is the Correct Answer While **Molluscum contagiosum** (MC) often shows lesions appearing in a linear pattern due to scratching (autoinoculation), this is termed **Pseudo-Koebner phenomenon**. The distinction lies in the underlying mechanism: * **True Koebner:** An isomorphic response in non-infectious inflammatory or metabolic skin diseases. * **Pseudo-Koebner:** Occurs in infectious conditions (e.g., MC, Viral Warts) where trauma physically spreads the infectious agent (virus) to a new site. #### Analysis of Incorrect Options * **B. Vitiligo:** This is a classic example of the **True Koebner phenomenon**. Trauma to the skin can trigger the destruction of melanocytes, leading to new depigmented patches in a linear or traumatic distribution. * **C. Psoriasis:** This is the most common and prototypical condition associated with the Koebner phenomenon. Approximately 25% of psoriasis patients exhibit this response following triggers like surgery, scratches, or sunburns. #### NEET-PG High-Yield Pearls * **Common True Koebner conditions:** Psoriasis, Lichen Planus, Vitiligo, Pityriasis Rubra Pilaris (PRP). * **Pseudo-Koebner conditions:** Molluscum contagiosum, Verruca plana (Warts), Impetigo. * **Reverse Koebner:** Disappearance of a lesion following trauma (e.g., Psoriasis, Granuloma annulare). * **Wolf’s Isotopic Response:** Occurrence of a new skin disease at the exact site of a previously healed, unrelated skin disease (most commonly post-Herpes Zoster).

Q: A young lady presents with lacy lesions in the oral cavity and genitals, and her proximal nail fold has extended onto the nail bed. What is the likely diagnosis?

Lichen planus. **Explanation:** The clinical presentation described is a classic case of **Lichen Planus (LP)**. The diagnosis is based on two pathognomonic features: 1. **Lacy lesions (Wickham Striae):** These are reticulate, white, lacy patterns found on the buccal mucosa and genitals. Oral involvement occurs in about 50% of patients with cutaneous LP. 2. **Pterygium formation:** This is the most characteristic nail finding in LP. It occurs when the **proximal nail fold fuses with the nail matrix and bed**, resulting in a V-shaped extension of skin over the nail. This leads to permanent scarring and destruction of the nail unit. **Why other options are incorrect:** * **Candidiasis:** Typically presents as white, curd-like plaques (thrush) that can be scraped off, leaving an erythematous base. In nails, it causes chronic paronychia (swelling of the nail fold) and onychomycosis, but it does **not** cause pterygium formation. * **Options C & D:** These are incorrect as the clinical triad of mucosal lacy lesions and pterygium is highly specific for Lichen Planus. **High-Yield Clinical Pearls for NEET-PG:** * **The 6 P’s of LP:** Planar (flat-topped), Purple, Polygonal, Pruritic, Papules, and Plaques. * **Koebner Phenomenon:** Development of lesions at sites of trauma (also seen in Psoriasis and Vitiligo). * **Nail LP:** Besides pterygium, look for "angel wing" deformity, longitudinal ridging, and thinning of the nail plate. * **Histopathology:** Characterized by "saw-tooth" rete ridges, Civatte bodies (apoptotic keratinocytes), and a band-like lymphocytic infiltrate at the dermo-epidermal junction.

Q: What are the characteristic bodies found in Lichen planus?

Civatte bodies. **Explanation:** The correct answer is **Civatte bodies**. These are characteristic histopathological findings in **Lichen Planus (LP)**. **1. Why Civatte bodies are correct:** Lichen planus is a chronic inflammatory condition characterized by a T-cell mediated attack on basal keratinocytes. This leads to **liquefaction degeneration** of the basal layer. The damaged keratinocytes undergo apoptosis and shrink into eosinophilic, rounded, anucleated structures known as **Civatte bodies** (also called colloid or cytoid bodies). They are typically found in the lower epidermis or upper dermis and contain deposits of IgM. **2. Analysis of Incorrect Options:** * **HP (Henderson-Paterson) bodies:** These are large, intracytoplasmic inclusion bodies seen in **Molluscum Contagiosum**, caused by the Poxvirus. * **Warthin-Finkeldey bodies:** These are multinucleated giant cells with eosinophilic nuclear and cytoplasmic inclusions, characteristic of **Measles** (Rubeola). * **Negri bodies:** These are pathognomonic eosinophilic intracytoplasmic inclusions found in pyramidal cells of the hippocampus and Purkinje cells of the cerebellum in **Rabies**. **3. High-Yield Clinical Pearls for NEET-PG:** * **Histopathology of LP:** Remember the mnemonic **"SAW"**: **S**aw-tooth rete ridges, **A**canthosis, and **W**ickham striae (clinically). Other features include hypergranulosis and a band-like lymphocytic infiltrate at the dermo-epidermal junction. * **Clinical 6 P’s of LP:** Planar, Purple, Polygonal, Pruritic, Papules, and Plaques. * **Koebner Phenomenon:** Positive in Lichen Planus, Psoriasis, and Vitiligo. * **Max Joseph Space:** Small areas of separation between the epidermis and dermis due to extensive basal cell degeneration in LP.

Q: Migratory necrolytic erythema is seen in which of the following conditions?

Glucagonoma syndrome. **Explanation:** **Migratory Necrolytic Erythema (MNE)** is a pathognomonic cutaneous marker for **Glucagonoma**, a rare alpha-cell tumor of the pancreas. The rash typically presents as pruritic, painful, erythematous plaques that progress to vesicles and bullae, eventually crusting and healing with hyperpigmentation. It most commonly affects the perineum, buttocks, and distal extremities. The underlying mechanism is thought to be related to hypoaminoacidemia, zinc deficiency, or the direct effect of excess glucagon causing inflammatory arachidonic acid release. **Analysis of Incorrect Options:** * **Peutz-Jeghers Syndrome:** Characterized by hamartomatous gastrointestinal polyps and **mucocutaneous hyperpigmentation** (melanotic macules) on the lips, buccal mucosa, and digits. * **Sarcoidosis:** Associated with various skin manifestations, most notably **Lupus Pernio** (violaceous plaques on the nose/cheeks) and **Erythema Nodosum** (painful pretibial nodules). * **Amyloidosis:** Classic skin findings include **"Pinch purpura"** (periorbital ecchymosis) and waxy, translucent papules or plaques due to amyloid deposition in the dermis. **High-Yield Clinical Pearls for NEET-PG:** * **Glucagonoma Syndrome (The 4 D's):** **D**ermatitis (MNE), **D**iabetes (mild), **D**epression, and **D**eep Vein Thrombosis (DVT). * **Laboratory findings:** Extremely high serum glucagon levels (>1000 pg/mL) and low serum amino acids. * **Treatment:** Somatostatin analogues (Octreotide) are used to control symptoms by inhibiting glucagon release before surgical resection.

Q: What is the recommended treatment for geographic tongue?

Routine observation at recall visits. **Explanation:** **Geographic Tongue**, also known as **Benign Migratory Glossitis**, is a common, benign inflammatory condition of the tongue. It is characterized by well-demarcated areas of atrophy (depapillation) of the filiform papillae, surrounded by a slightly raised, white-to-yellowish circinate border. These lesions "migrate" over time as one area heals and another develops. **Why Option D is correct:** The condition is **asymptomatic** in the vast majority of cases and has no malignant potential. Because it is a self-limiting, benign condition with an unknown etiology (though sometimes linked to psoriasis or atopy), the standard of care is **routine observation and patient reassurance**. Treatment is only indicated if the patient experiences a burning sensation (glossodynia), in which case topical steroids or zinc supplements may be used. **Why other options are incorrect:** * **A. Excision:** This is a benign, diffuse, and migratory mucosal condition; surgical intervention is unnecessary and contraindicated. * **B. Penicillin:** Geographic tongue is not a bacterial infection (like syphilis or strep throat); antibiotics have no role in its management. * **C. Nystatin:** This is an antifungal used for Oral Candidiasis (Thrush). While geographic tongue can mimic the appearance of some fungal infections, it is not caused by *Candida*. **High-Yield NEET-PG Pearls:** * **Histopathology:** Shows "Munro’s microabscesses" (neutrophils in the epithelium), similar to psoriasis. * **Association:** Strongly associated with **Fissured Tongue** (Scrotal tongue). * **Clinical Feature:** The loss of **filiform papillae** is the hallmark; fungiform papillae often remain as red dots. * **Trigger:** Can be exacerbated by spicy or acidic foods.

Q: Keloid formation is not typically seen over which of the following areas?

Eyelids. **Explanation:** Keloids are benign fibroproliferative growths resulting from an exaggerated healing response to skin injury. They are characterized by the excessive deposition of Type I and Type III collagen that extends **beyond the boundaries** of the original wound. **Why Eyelids are the Correct Answer:** Keloid formation is highly dependent on skin tension and the density of skin appendages. The **eyelids**, along with the **penis, scrotum, palms, and soles**, are considered "immune" or highly resistant to keloid formation. This is primarily due to the extreme laxity of the skin and the lack of high dermal tension in these regions. **Analysis of Incorrect Options:** * **Ear:** The earlobes are one of the most common sites for keloids, often triggered by ear piercing. * **Face:** While less common than the chest, keloids can occur on the face, particularly along the jawline (often associated with acne or folliculitis barbae). * **Neck:** The anterior and lateral neck are high-tension areas prone to hypertrophic scars and keloids following trauma or surgical procedures. **Clinical Pearls for NEET-PG:** 1. **Commonest Site:** The **presternal area** (over the sternum) is the most common site due to high constant skin tension. Other common sites include the deltoid region and upper back. 2. **Histology:** Characterized by thick, eosinophilic, "glassy" collagen bundles (hyalinized collagen). 3. **Treatment:** Intralesional **Triamcinolone acetonide** (corticosteroid) is the first-line treatment. 4. **Key Difference:** Unlike hypertrophic scars, keloids do not regress spontaneously and extend beyond the original margin of injury.

Question 1

All of the following are true regarding erythrocyanosis frigida, EXCEPT:

Accepted Answer

Seen exclusively in alcoholic males

Answer

Occurs in the lower third of leg on leg or ankle

Answer

Causes Bazin's ulcer

Answer

Sympathectomy may be beneficial in some patients

Question 2

What is the primary function of Langerhans cells?

Accepted Answer

Antigen presentation

Answer

Phagocytosis

Answer

Associated with autoimmune conditions

Answer

Associated with chronic infections

Question 3

Which of the following conditions does not show an isomorphic type of Koebner phenomenon?

Accepted Answer

Molluscum contagiosum

Answer

Vitiligo

Answer

Psoriasis

Answer

None of the above

Question 4

A young lady presents with lacy lesions in the oral cavity and genitals, and her proximal nail fold has extended onto the nail bed. What is the likely diagnosis?

Accepted Answer

Lichen planus

Answer

Candidiasis

Answer

Both

Answer

None

Question 5

What are the characteristic bodies found in Lichen planus?

Accepted Answer

Civatte bodies

Answer

HP bodies

Answer

Warthin Finkeldy bodies

Answer

Negri bodies

Question 6

A patient with a 4-year history of diabetes presents with the skin lesion shown in the image. What is the most likely diagnosis?

Accepted Answer

Necrolytic migratory erythema

Answer

Bullous disease of diabetes

Answer

Necrobiosis lipoidica diabeticorum

Answer

Pigmented purpuric dermatosis

Question 7

Migratory necrolytic erythema is seen in which of the following conditions?

Accepted Answer

Glucagonoma syndrome

Answer

Peutz-Jeghers syndrome

Answer

Sarcoidosis

Answer

Amyloidosis

Question 8

What is the recommended treatment for geographic tongue?

Accepted Answer

Routine observation at recall visits

Answer

Excision of the lesion

Answer

Penicillin therapy

Answer

Topical application of Nystatin

Question 9

All of the following perforating disorders are associated with chronic renal failure EXCEPT:

Accepted Answer

Calciphylaxis

Answer

Reactive perforating collagenosis

Answer

Elastosis perforans serpiginosa

Answer

Kyrle disease

Question 10

Keloid formation is not typically seen over which of the following areas?

Accepted Answer

Eyelids

Answer

Ear

Answer

Face

Answer

Neck

Basic Dermatology — MCQs

Basic Dermatology — MCQs

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