Pediatric Dermatology Practice Questions

Q: A male child with cryptorchidism presents with large black scales on body flexures. Skin biopsy showed hypergranulosis and steroid sulfatase deficiency. What is the probable diagnosis?

X-linked ichthyosis nigra. ### Explanation The correct diagnosis is **X-linked Recessive Ichthyosis (XLRI)**, also known as Ichthyosis Nigra. **Why it is correct:** XLRI is caused by a deficiency of the enzyme **steroid sulfatase**, leading to an accumulation of cholesterol sulfate in the epidermis. This disrupts lipid metabolism and prevents normal desquamation. * **Clinical Presentation:** It typically presents with large, dark/brown "dirty" scales that characteristically **involve the neck and flexures** (unlike Ichthyosis Vulgaris). * **Systemic Associations:** It is frequently associated with **cryptorchidism** (undescended testes) and corneal opacities. * **Histopathology:** Unlike Ichthyosis Vulgaris, XLRI shows **hypergranulosis** (increased granular layer) or a normal granular layer. **Why the other options are incorrect:** * **Ichthyosis Vulgaris:** The most common type; it **spares the flexures** and histologically shows an **absent or diminished granular layer** (hypogranulosis). It is not associated with steroid sulfatase deficiency. * **Lamellar Ichthyosis:** Presents at birth as a **collodion membrane**. Scales are large and plate-like, often associated with ectropion and eclabium. It is autosomal recessive. * **Nonbullous Ichthyosiform Erythroderma (NBIE):** Presents with generalized erythroderma and fine white scales. It does not show the specific steroid sulfatase deficiency or the "nigra" (dark) scale pattern. **NEET-PG High-Yield Pearls:** 1. **Placental Sulfatase Deficiency:** Mothers carrying a fetus with XLRI often have **delayed labor** due to low estrogen levels (steroid sulfatase is needed to produce estriol). 2. **Mnemonic:** XLRI = **D**ark scales, **D**irty neck, **D**escend (Cryptorchidism), **D**elayed labor. 3. **Inheritance:** As the name suggests, it is X-linked recessive, affecting males almost exclusively.

Q: What is the mode of inheritance of incontinentia pigmenti?

X-linked dominant. **Explanation:** **Incontinentia Pigmenti (Bloch-Sulzberger syndrome)** is a rare multisystem neurocutaneous disorder caused by a mutation in the **IKBKG gene** (formerly NEMO). 1. **Why X-linked Dominant is correct:** The inheritance is **X-linked dominant**. The mutation is typically **lethal in males** in utero, which explains why the clinical phenotype is seen almost exclusively in females. Affected females survive due to functional mosaicism resulting from X-chromosome inactivation (Lyonization). 2. **Why other options are incorrect:** * **Autosomal Dominant/Recessive:** The gene is located on the X chromosome (Xq28), ruling out autosomal patterns. * **X-linked Recessive:** In recessive conditions, heterozygous females are usually asymptomatic carriers. In IP, a single mutated allele is sufficient to cause the disease in females and cause lethality in males. **Clinical Pearls for NEET-PG:** * **Four Stages of Skin Lesions:** 1. **Vesicular:** Linear vesicles (present at birth/infancy). 2. **Verrucous:** Hyperkeratotic linear plaques. 3. **Hyperpigmented:** "Swirl-like" or **"Marble cake"** pigmentation along **Blaschko’s lines**. 4. **Hypopigmented:** Atrophic, hairless patches. * **Associated Findings:** "Peg-shaped" or conical teeth (hypodontia), cicatricial alopecia, and CNS involvement (seizures/intellectual disability). * **Histopathology:** Characteristic **eosinophilic spongiosis** is seen in the vesicular stage.

Q: Combination of retinitis pigmentosa and ichthyosis is seen in which syndrome?

Refsum's syndrome. **Explanation:** **Refsum’s Syndrome** (Heredopathia Atactica Polyneuritiformis) is an autosomal recessive metabolic disorder caused by a deficiency in the enzyme **phytanoyl-CoA hydroxylase**. This leads to the systemic accumulation of **phytanic acid**. The classic clinical tetrad includes: 1. **Ichthyosis:** Usually presents as mild, generalized scaling. 2. **Retinitis Pigmentosa:** Leading to night blindness and constricted visual fields. 3. **Peripheral Neuropathy:** Chronic, progressive motor and sensory loss. 4. **Cerebellar Ataxia.** Other features include sensorineural deafness and cardiomyopathy. **Analysis of Incorrect Options:** * **A. Netherton Syndrome:** Characterized by the triad of **Ichthyosis linearis circumflexa**, **Bamboo hair** (Trichorrhexis invaginata), and **Atopy**. It does not involve retinitis pigmentosa. * **C. Down’s Syndrome:** A chromosomal disorder (Trisomy 21) associated with intellectual disability, characteristic facies, and dermatological findings like xerosis, syringomas, and alopecia areata, but not ichthyosis with retinitis pigmentosa. * **D. Sjögren-Larsson Syndrome (likely intended by "Mob's"):** This syndrome presents with the triad of **Ichthyosis**, **Spastic diplegia/quadriplegia**, and **Intellectual disability**. It features "glistening white dots" in the retina, not retinitis pigmentosa. **NEET-PG High-Yield Pearls:** * **Dietary Management:** The primary treatment for Refsum’s is a diet low in phytanic acid (avoiding green leafy vegetables, dairy, and ruminant fats). * **Differential Diagnosis:** If you see Ichthyosis + Neurological symptoms, think Refsum’s (Ataxia/Retinitis) or Sjögren-Larsson (Spasticity). * **Ichthyosis Linearis Circumflexa** is the pathognomonic skin finding for Netherton Syndrome.

Q: All of the following result in endogenous pigmentation of teeth except?

Vitamin B deficiency. **Explanation:** Endogenous (intrinsic) pigmentation of teeth occurs when chromogenic materials are deposited within the enamel or dentin during tooth development. **Why Vitamin B deficiency is the correct answer:** Vitamin B deficiency (specifically B12 or Folate) is associated with oral manifestations like glossitis, angular cheilitis, and **hyperpigmentation of the oral mucosa** (especially in dark-skinned individuals). However, it does **not** cause endogenous staining of the teeth. Tooth discoloration is typically linked to metabolic disorders, hematological conditions, or drug ingestion during odontogenesis. **Analysis of Incorrect Options:** * **Tetracycline:** This is the most classic cause of intrinsic staining. The drug binds to calcium phosphate and is deposited in the teeth during mineralization, causing a **yellow-brown to gray** discoloration that fluoresces under UV light. * **Fetal Jaundice & Erythroblastosis Fetalis:** Both conditions lead to hyperbilirubinemia. High levels of circulating bilirubin during the period of tooth calcification result in the deposition of bile pigments in the dental matrix. This typically manifests as **greenish (Chlorodontia)** or yellowish-brown discoloration of the primary teeth. **High-Yield Clinical Pearls for NEET-PG:** * **Porphyria (Congenital Erythropoietic Porphyria):** Causes a characteristic **reddish-brown** discoloration (Erythrodontia) that shows red fluorescence under Wood’s lamp. * **Fluorosis:** Causes "mottled enamel" with chalky white spots or brown pitting due to excessive fluoride intake (>1.5 ppm) during tooth development. * **Alkaptonuria:** May result in a brownish-black discoloration of teeth. * **Timing:** For endogenous staining to occur, the systemic insult must happen while the tooth crowns are forming (in utero for primary teeth; up to age 8 for permanent teeth).

Q: An adolescent boy complains of a splotchy red rash on the nape of his neck, discovered when he had his head shaved for football season. The rash seems to become more prominent with exercise or emotion. His mother notes that he has had the rash since infancy, but that it became invisible as hair grew. He had a similar rash on his eyelids that resolved in the newborn period. What is the most likely diagnosis?

Salmon patch. **Explanation:** The clinical presentation is classic for a **Salmon patch** (also known as *Nevus simplex*). These are the most common vascular lesions of infancy, representing persistent fetal dermal capillaries. **Why Salmon Patch is correct:** * **Location:** They typically occur on the midline, specifically the nape of the neck (often called a **"Stork bite"**) or the eyelids/glabella (often called an **"Angel kiss"**). * **Evolution:** While facial lesions (eyelids) usually fade within 1–2 years, nuchal lesions (nape of the neck) often persist into adulthood, becoming "hidden" by hair. * **Dynamic Nature:** The rash characteristically becomes more erythematous and prominent during periods of increased blood flow, such as exercise, crying, or emotional stress. **Why other options are incorrect:** * **Sebaceous nevus:** A congenital hamartoma that appears as a yellowish-orange, hairless plaque, usually on the scalp. It becomes verrucous (warty) during puberty due to hormonal influence, not red/splotchy with exercise. * **Neonatal acne:** Presents as inflammatory papules and pustules on the face around 2–3 weeks of age; it does not persist from infancy to adolescence as a flat red patch. * **Pustular melanosis (Transient Neonatal Pustular Melanosis):** Characterized by fragile pustules that rupture to leave a collarette of scale and hyperpigmented macules. It resolves within weeks to months of birth. **Clinical Pearls for NEET-PG:** * **Salmon Patch vs. Port-Wine Stain:** Salmon patches are midline, blanchable, and often fade (except nuchal ones). Port-wine stains (*Nevus flammeus*) are usually lateral, do not fade, and grow proportionately with the child. * **Nuchal persistence:** Approximately 50% of nuchal salmon patches persist indefinitely. * **Management:** Reassurance is the mainstay as they are benign and asymptomatic.

Q: Sturge-Weber syndrome is associated with which of the following?

Port wine stain. **Explanation:** **Sturge-Weber Syndrome (SWS)**, also known as encephalotrigeminal angiomatosis, is a neurocutaneous disorder characterized by the presence of a **Port-wine stain (PWS)**, also known as Nevus Flammeus. 1. **Why Option A is Correct:** The hallmark of SWS is a congenital capillary malformation (Port-wine stain) typically involving the skin supplied by the **trigeminal nerve** (most commonly the V1 and V2 distributions). Pathophysiologically, it is caused by a somatic mutation in the **GNAQ gene**. This cutaneous lesion is associated with ipsilateral leptomeningeal angiomas and glaucoma. 2. **Why Other Options are Incorrect:** * **B. Cavernous hemangioma:** These are deep vascular malformations (slow-flow) that appear as soft, compressible blue masses. They are not a diagnostic feature of SWS. * **C. Lymphangioma:** These are malformations of the lymphatic system (e.g., cystic hygroma) and are unrelated to the capillary-venous pathology of SWS. * **D. Hemangiosarcoma:** This is a rare, highly malignant neoplasm of the vascular endothelium, whereas SWS involves benign congenital malformations. **High-Yield Clinical Pearls for NEET-PG:** * **The Triad:** 1. Facial Port-wine stain, 2. Leptomeningeal angiomatosis (causing seizures and hemiparesis), 3. Glaucoma. * **Radiology:** Skull X-ray or CT shows characteristic **"Tram-track" calcifications** (gyriform calcifications) due to cortical atrophy and calcification of the underlying angiomas. * **Distribution:** A PWS involving the **upper eyelid** (V1 distribution) carries the highest risk for associated CNS involvement. * **Treatment:** Pulsed Dye Laser (PDL) is the gold standard for treating the Port-wine stain.

Q: A young 8-year-old boy presents with multiple, small, pinpoint, shiny, papular lesions on the dorsal aspect of his hands, forearms, and penis. What is the most likely diagnosis?

Lichen nitidus. ### **Explanation** The clinical presentation of multiple, small, pinpoint, shiny, flesh-colored papules in a child is classic for **Lichen Nitidus**. #### **Why Lichen Nitidus is Correct** Lichen nitidus is a chronic inflammatory dermatosis characterized by tiny (1–2 mm), uniform, **flat-topped, shiny (glistening)**, skin-colored papules. It typically affects children and young adults. Common sites of involvement include the **dorsal hands, forearms, chest, and the shaft/glans of the penis**. A key histopathological feature often tested is the **"claw clutching a ball"** appearance (elongated rete ridges encircling a dermal lymphocytic infiltrate). #### **Why Other Options are Incorrect** * **Molluscum Contagiosum:** These are larger, pearly-white papules characterized by **central umbilication**. They are viral (Poxvirus) and usually not as "pinpoint" or numerous in a localized area like the hands. * **Scabies:** While it involves the hands and penis, it presents with **intense nocturnal pruritus**, burrows, and inflammatory vesicles/pustules rather than shiny, uniform papules. * **Lichen Planus (LP):** Although related, LP presents with larger, **violaceous (purple), polygonal, pruritic** plaques often associated with **Wickham striae**. Lichen nitidus is often considered a variant of LP but is clinically distinct due to its smaller size and lack of color. #### **NEET-PG High-Yield Pearls** * **Koebner Phenomenon:** Lichen nitidus (like Lichen Planus and Psoriasis) can show linear lesions due to trauma. * **Clinical Sign:** The lesions are often described as having a **"glistening"** or "sand-like" appearance under bright light. * **Treatment:** Usually asymptomatic and self-limiting; topical steroids or tacrolimus can be used if pruritic. * **Histology Keyword:** "Claw clutching a ball" (Infiltrate of lymphocytes and histiocytes trapped by epidermal colrettes).

Q: What is true about Acrodermatitis enteropathica?

Lifelong treatment is required.. **Acrodermatitis Enteropathica (AE)** is a rare genetic disorder characterized by a severe deficiency of zinc. ### **Explanation of Options** * **Correct Option (A):** AE is caused by a mutation in the **SLC39A4 gene**, which encodes the **ZIP4 transporter** responsible for zinc uptake in the enterocytes of the duodenum and jejunum. Since the genetic defect in the transporter is permanent, patients cannot absorb dietary zinc effectively. Therefore, **lifelong oral zinc supplementation** (usually 3–5 mg/kg/day of elemental zinc) is mandatory to prevent relapse. * **Option B:** It is an **Autosomal Recessive** disorder, not dominant. * **Option C:** Zinc is a vital cofactor for DNA polymerase and alkaline phosphatase. Deficiency leads to **impaired wound healing** and increased susceptibility to secondary infections (especially *Candida albicans* and *Staph. aureus*). * **Option D:** Zinc absorption is **severely impaired** due to the defective ZIP4 transporter. ### **Clinical Pearls for NEET-PG** 1. **The Classic Triad:** Periorificial and acral dermatitis, Alopecia, and Diarrhea (seen in only 20% of cases). 2. **Timing of Presentation:** Symptoms typically appear **after weaning** from breast milk. Breast milk contains a zinc-binding ligand (citric acid) that aids absorption, which is absent in cow's milk. 3. **Dermatological Findings:** Symmetrical, erythematous, vesiculobullous, and eczematous plaques around the mouth, anus, and distal extremities. 4. **Diagnosis:** Low serum zinc levels (<50 µg/dL) and **low serum alkaline phosphatase** (a zinc-dependent enzyme). 5. **Acquired Form:** Can occur in adults due to chronic alcoholism, malabsorption, or prolonged parenteral nutrition without zinc supplementation.

Q: A child presents with a vesiculobullous, pustular rash around the mouth and on the extremities, along with alopecia and diarrhea. What is the most likely nutritional deficiency?

Zinc Deficiency. ***Zinc Deficiency*** - This clinical presentation represents a classic case of **acrodermatitis enteropathica**, a condition caused by zinc deficiency, characterized by a vesiculobullous, pustular, and eczematous rash in a **periorificial** (around the mouth) and **acral** distribution. - Other key features of zinc deficiency include **alopecia** (hair loss), chronic **diarrhea**, **impaired growth**, and **immunodeficiency**, leading to recurrent infections. *Vitamin C Deficiency* - Known as **scurvy**, this deficiency leads to impaired collagen synthesis, resulting in manifestations like **petechiae**, **ecchymoses**, perifollicular hemorrhage, **bleeding gums**, and **corkscrew hairs**. - In infants, it can present with **subperiosteal hemorrhages**, causing severe pain and reluctance to move (**pseudoparalysis**), but not the periorificial rash seen here. *Vitamin D Deficiency* - This deficiency primarily affects bone mineralization, leading to **rickets** in children and **osteomalacia** in adults. Clinical signs include **bowed legs** (genu varum), **rachitic rosary** (beading of the ribs), and **craniotabes** (soft skull). - Cutaneous manifestations are not a feature of vitamin D deficiency; its role is primarily in **calcium homeostasis** and bone health. *Copper Deficiency* - Copper deficiency primarily manifests with hematological abnormalities like **microcytic anemia** (refractory to iron treatment) and neurological symptoms such as **myelopathy** and peripheral neuropathy. - Cutaneous signs are rare but can include **hypopigmentation** of the skin and kinky, brittle hair (**pili torti**), which are features of the genetic disorder **Menkes disease**.

Question 1

A male child with cryptorchidism presents with large black scales on body flexures. Skin biopsy showed hypergranulosis and steroid sulfatase deficiency. What is the probable diagnosis?

Accepted Answer

X-linked ichthyosis nigra

Answer

Ichthyosis vulgaris

Answer

Ichthyosis lamellar

Answer

Nonbullous ichthyosiform erythroderma

Question 2

What is the mode of inheritance of incontinentia pigmenti?

Accepted Answer

X-linked dominant

Answer

Autosomal dominant

Answer

Autosomal recessive

Answer

X-linked recessive

Question 3

Combination of retinitis pigmentosa and ichthyosis is seen in which syndrome?

Accepted Answer

Refsum's syndrome

Answer

Netherton syndrome

Answer

Down's syndrome

Answer

Mob's syndrome

Question 4

All of the following result in endogenous pigmentation of teeth except?

Accepted Answer

Vitamin B deficiency

Answer

Tetracycline

Answer

Fetal jaundice

Answer

Erythroblastosis fetalis

Question 5

A 2-year-old child, born out of a consanguineous marriage, presented with a history of collodion membrane. Physical examination revealed large, thick, plate-like brown scaling with generalized distribution, but no erythroderma or ectropion. Which of the following is the most likely diagnosis?

Accepted Answer

Lamellar ichthyosis

Answer

Ichthyosis vulgaris

Answer

X-linked ichthyosis

Answer

Netherton syndrome

Question 6

An adolescent boy complains of a splotchy red rash on the nape of his neck, discovered when he had his head shaved for football season. The rash seems to become more prominent with exercise or emotion. His mother notes that he has had the rash since infancy, but that it became invisible as hair grew. He had a similar rash on his eyelids that resolved in the newborn period. What is the most likely diagnosis?

Accepted Answer

Salmon patch

Answer

Sebaceous nevus

Answer

Neonatal acne

Answer

Pustular melanosis

Question 7

Sturge-Weber syndrome is associated with which of the following?

Accepted Answer

Port wine stain

Answer

Cavernous hemangioma

Answer

Lymphangioma

Answer

Hemangiosarcoma

Question 8

A young 8-year-old boy presents with multiple, small, pinpoint, shiny, papular lesions on the dorsal aspect of his hands, forearms, and penis. What is the most likely diagnosis?

Accepted Answer

Lichen nitidus

Answer

Molluscum contagiosum

Answer

Scabies

Answer

Lichen planus

Question 9

What is true about Acrodermatitis enteropathica?

Accepted Answer

Lifelong treatment is required.

Answer

It is an autosomal dominant disorder.

Answer

Wound healing is not affected.

Answer

Zinc absorption is normal.

Question 10

A child presents with a vesiculobullous, pustular rash around the mouth and on the extremities, along with alopecia and diarrhea. What is the most likely nutritional deficiency?

Accepted Answer

Zinc Deficiency

Answer

Vitamin C Deficiency

Answer

Vitamin D Deficiency

Answer

Copper Deficiency

Pediatric Dermatology — MCQs

Pediatric Dermatology — MCQs

On this page

Practice by Chapter

Want unlimited practice?