INI-CET 2026 Practice Questions

Q: An infant presents with pruritic lesions distributed over the hands, feet, and periumbilical region. Which of the following diagnoses best fits this clinical picture?

Scabies. ***Scabies*** - The distribution pattern involving the **hands, feet, and periumbilical region** is a hallmark sign of **scabies** infestation in infants, where the mite (*Sarcoptes scabiei*) prefers skin with a thin stratum corneum. - Intense **pruritus** that is often worse at night is the classic symptom resulting from a **delayed type IV hypersensitivity reaction** to the mites, their feces, and eggs. *Atopic dermatitis* - Classically presents as **erythematous, scaly patches** on the **extensor surfaces** of infants (often affecting cheeks or scalp), rather than the specific web space or periumbilical distribution seen in scabies. - While it is highly pruritic, it is typically a chronic, relapsing condition associated with a **personal or family history of atopy** (e.g., asthma, allergic rhinitis). *Bullous impetigo* - Presents as **flaccid, fluid-filled bullae** that rupture to leave a thin, varnish-like crust, typically caused by **Staphylococcus aureus**. - It is generally not associated with the intense, generalized pruritus seen in infestation diseases and usually lacks the specific distribution pattern described. *Eczema* - This is an umbrella term often used interchangeably with atopic dermatitis, characterized by **inflammation, scaling, and dryness**. - It does not involve **burrows or papules** in the webs of fingers or wrists, which are characteristic physical exam findings of scabies infestation.

Q: A female presents with greenish frothy discharge; whiff test and Amsel’s criteria are negative. What microscopy feature is expected?

Motile flagellates. ***Motile flagellates*** - The presentation of **greenish, frothy vaginal discharge** is a classic clinical feature of **trichomoniasis**, caused by the protozoan parasite *Trichomonas vaginalis*. - Microscopic examination of a **wet mount** will reveal the characteristic **motile, pear-shaped flagellated trophozoites**. *Pseudohyphae* - These are indicative of a **Candida albicans** (yeast) infection, which typically presents with **thick, white, curd-like discharge**. - While pruritus is common with candidiasis, the discharge is not classically described as greenish or frothy. *Clue cells* - These represent **bacterial vaginosis** (BV), characterized by epithelial cells coated with *Gardnerella vaginalis*. - The prompt explicitly states that **Amsel’s criteria** and the **whiff test** are negative, which effectively rules out a diagnosis of BV. *Gram-negative diplococci* - This finding is associated with **Neisseria gonorrhoeae** infection, which often presents with **purulent cervical discharge** and cervicitis. - While *N. gonorrhoeae* can cause discharge, it does not match the specific description of frothy green discharge or the expected microscopic findings of a protozoan infection.

Q: A male patient reports painful vesicular eruptions on the penis. Based on this presentation, which of the following is the most likely causative agent?

Herpes simplex virus. ***Herpes simplex virus*** - Infection with **Herpes simplex virus (HSV-2)** typically manifests as clusters of **painful vesicles** that rupture to form shallow, erythematous ulcers on the genitalia. - The clinical presentation is classic for primary genital herpes, which is often accompanied by **inguinal lymphadenopathy** and systemic symptoms like fever or malaise. *Haemophilus ducreyi* - This bacterium causes **chancroid**, which presents as a painful, deep, necrotic, and **purulent ulcer** rather than clusters of vesicles. - The base of the ulcer typically has gray/yellow exudate and bleeds easily, unlike the clear vesicular lesions of HSV. *Human papillomavirus* - This virus causes **condyloma acuminatum** (genital warts), which appear as **fleshy, cauliflower-like growths** rather than vesicular eruptions. - These lesions are usually asymptomatic or pruritic and are not typically associated with painful vesicle formation or acute rupture. *Treponema pallidum* - This organism causes **syphilis**, where the primary stage presents as a **chancre**, which is a **painless, indurated ulcer** with a clean base. - Unlike the painful vesicles of HSV, the primary syphilitic lesion is classically described as non-tender and associated with **regional lymphadenopathy**.

Q: A newborn presents with a skin lesion as shown. The infant is feeding normally, has no fever, hypotension, or shock signs. Which diagnosis is most likely?

Neonatal pemphigus due to transplacental antibody transfer. ***Neonatal pemphigus due to transplacental antibody transfer*** - This condition occurs due to the in utero transfer of maternal **pemphigus antibodies** (anti-desmoglein 1 or 3) across the placenta to the fetus. - It is a **transient condition** that typically resolves spontaneously within a few weeks as the maternal antibodies are cleared from the infant's circulation. *Staphylococcal scalded skin syndrome* - This typically presents with a **toxic-appearing infant** who is febrile and irritable, which contradicts the stable clinical presentation described. - It is caused by **exfoliative toxins** produced by *Staphylococcus aureus* and usually involves widespread erythema followed by desquamation rather than isolated bullae. *Bullous pemphigoid* - This is an **autoimmune blistering disease** that is extremely rare in newborns and typically manifests in elderly populations. - If present, it would be associated with distinct **subepidermal bullae** and intense **pruritus**, which is not the standard presentation for this case. *Epidermolysis bullosa* - This is a group of **genetic blistering disorders** characterized by skin fragility and blistering at sites of minor trauma or at birth. - The clinical history of a well-appearing, thriving infant makes a sudden onset of a generalized blistering disorder like this less suspicious than transient transplacental antibody transfer.

Question 1

An infant presents with pruritic lesions distributed over the hands, feet, and periumbilical region.
Which of the following diagnoses best fits this clinical picture?

Accepted Answer

Scabies

Answer

Atopic dermatitis

Answer

Bullous impetigo

Answer

Eczema

Question 2

A female presents with greenish frothy discharge; whiff test and Amsel’s criteria are negative.
What microscopy feature is expected?

Accepted Answer

Motile flagellates

Answer

Pseudohyphae

Answer

Clue cells

Answer

Gram-negative diplococci

Question 3

A male patient reports painful vesicular eruptions on the penis. Based on this presentation,
which of the following is the most likely causative agent?

Accepted Answer

Herpes simplex virus

Answer

Haemophilus ducreyi

Answer

Human papillomavirus

Answer

Treponema pallidum

Question 4

A newborn presents with a skin lesion as shown. The infant
is feeding normally, has no fever, hypotension, or shock signs.
Which diagnosis is most likely?

Accepted Answer

Neonatal pemphigus due to transplacental antibody transfer

Answer

Staphylococcal scalded skin syndrome

Answer

Bullous pemphigoid

Answer

Epidermolysis bullosa

INI-CET 2026

Dermatology