NEET-PG 2024 Practice Questions

Q: What is the period called between the entry of an organism into the host and the point of maximum infectivity?

Latent Period. ***Latent Period*** - The **latent period** is the time from entry of an organism into the host until the host becomes **infectious** (able to transmit the disease to others). - During this phase, the organism replicates within the host, but the host is not yet shedding sufficient pathogen to transmit infection. - This period ends when the host begins to shed the pathogen and can transmit it to susceptible individuals, which often coincides with peak infectivity in many diseases. - The latent period is crucial in epidemiology for understanding disease transmission dynamics and implementing control measures. *Generation Time* - **Generation time** (or serial interval) in epidemiology refers to the time interval between the onset of infection in a primary case and the onset of infection in a secondary case. - It reflects the average time between successive generations in a chain of transmission. - This is distinct from the latent period and does not specifically address the period until infectivity begins. *Incubation Period* - The **incubation period** is the time between exposure to an infectious agent and the **onset of clinical symptoms**. - It may overlap with or differ from the latent period; some diseases are infectious before symptoms appear (e.g., measles, chickenpox), while others become infectious only after symptoms develop. - The incubation period does not directly correlate with the timing of infectivity. *Prodromal Period* - The **prodromal period** occurs after the incubation period and is characterized by the appearance of **early, nonspecific symptoms** (e.g., malaise, fever, fatigue). - These symptoms precede the characteristic manifestations of the disease. - During the prodromal period, the person may already be infectious, but this period is defined by symptom characteristics, not infectivity timing.

Q: A patient presents with loss of sensation along the ulnar nerve path. The histology is shown in the image, and a Lepromin test was performed. What is the expected outcome?

Tuberculoid leprosy with lepromin positive. ***Tuberculoid leprosy with lepromin positive*** - The image shows **epithelioid cell granulomas** with sparse lymphocytes, characteristic of a **strong cell-mediated immune response** seen in tuberculoid leprosy. - Patients with tuberculoid leprosy typically have a **positive lepromin skin test**, indicating a robust CMI response capable of containing the infection. *Borderline leprosy with lepromin positive* - Borderline leprosy exhibits a wider spectrum of histological features, often with a mix of tuberculoid and lepromatous characteristics, and is typically **lepromin variable or weakly positive**. - The significant presence of well-formed granulomas in the image points more strongly towards the tuberculoid pole rather than borderline forms. *Lepromatous leprosy with lepromin positive* - Lepromatous leprosy is characterized by a **weak or absent cell-mediated immune response**, leading to diffuse infiltration of **foamy macrophages (Virchow cells)** packed with abundant *M. leprae*, and the **absence of well-formed granulomas**. - Patients with lepromatous leprosy are typically **lepromin negative** due to their anergic immune state. *Scrofuloderma* - **Scrofuloderma** is a form of **cutaneous tuberculosis** resulting from direct extension of underlying tuberculous lymphadenitis or osteomyelitis to the skin. - While it involves granulomatous inflammation, the clinical context of ulnar nerve involvement and the specific histological appearance of well-formed epithelioid granulomas with sparse bacilli are more indicative of tuberculoid leprosy.

Q: A patient's skin biopsy shows a box-shaped or square-shaped pattern of inflammatory infiltrate, as shown in the image. What is the most likely diagnosis?

Lichen planus. ***Lichen planus*** - The image shows a characteristic **"box-shaped" or "square-shaped" infiltrate** of lymphocytes at the dermal-epidermal junction, obscuring the basal layer. - Other features consistent with lichen planus include **hypergranulosis**, **sawtooth rete ridges**, and **Civatte bodies** (apoptotic keratinocytes) in the basal layer. *Lichen amyloidosis* - This condition is characterized by deposition of **amyloid material** in the papillary dermis, often associated with keratinocyte necrosis. - While it can present with pruritic papules similar to lichen planus, the histology specifically shows **amyloid deposits**, not the typical basal cell damage or band-like infiltrate seen in the image. *Morphea* - Morphea is a form of localized scleroderma, characterized by **thickening of collagen bundles** in the dermis and subcutaneous tissue, leading to hardened skin plaques. - Histologically, it involves **sclerosis** and homogenization of collagen, with a sparse inflammatory infiltrate, which is distinct from the dense band-like infiltrate and epidermal changes shown. *Lichen nitidus* - Lichen nitidus is characterized by **small, discrete granulomas** within the papillary dermis (the "ball-and-claw" appearance), with epithelial extensions embracing the inflammatory infiltrate. - It involves a more **localized inflammatory process** and distinct granulomatous appearance, rather than the broad, band-like infiltrate seen across the dermal-epidermal junction in this image.

Q: A patient presents with orange-hued skin lesions and hyperkeratotic palms and soles. A biopsy shows alternating parakeratosis and orthokeratosis. What is the most likely diagnosis?

Pityriasis rubra pilaris. ***Pityriasis rubra pilaris*** - This condition classically presents with **salmon-colored to orange-hued plaques** and **hyperkeratotic palms and soles**. - Histologically, Pityriasis rubra pilaris is characterized by **alternating parakeratosis and orthokeratosis** in vertical and horizontal directions ("checkerboard" pattern). *Follicular psoriasis* - While psoriasis can present with hyperkeratosis and scales, **follicular psoriasis** specifically involves the hair follicles, seen as follicular papules and pustules. - The classic alternating parakeratosis and orthokeratosis is more indicative of PRP than of follicular psoriasis, which typically shows more uniform parakeratosis. *Keratosis follicularis* - Also known as Darier disease, this condition presents with **greasy, crusted, foul-smelling papules** on seborrheic areas. - Histopathology reveals characteristic **dyskeratosis** with acantholytic cells (corps ronds and grains), which is different from the described alternating parakeratosis and orthokeratosis. *Ichthyosis vulgaris* - This is a genetic disorder characterized by **dry, scaly skin** due to impaired epidermal barrier function, often worse in winter. - Histopathology typically shows a **diminished or absent granular layer** and compact orthokeratosis without parakeratosis, differing from the biopsy findings.

Q: A patient presents with annular, scaly plaques with perifollicular extension on the trunk. What is the most likely diagnosis?

Tinea. ***Tinea*** - **Tinea corporis** classically presents with **annular, scaly plaques with central clearing** and an active, raised border. - On hairy areas or with follicular involvement, dermatophyte infections show **perifollicular extension** as the fungus invades hair follicles. - The **annular morphology with scale** is pathognomonic for dermatophyte infection, confirmed by **KOH preparation** showing septate hyphae. - Common sites include trunk, limbs, and any body area with hair follicles. *Psoriasis* - Presents with **well-demarcated, erythematous plaques** with **silvery-white scales**, typically on extensor surfaces (elbows, knees, scalp). - **Follicular psoriasis** is rare and shows **pinpoint follicular papules**, not annular plaques with perifollicular extension. - Auspitz sign (pinpoint bleeding on scale removal) helps differentiate from tinea. *Lichen planus* - Characterized by **pruritic, polygonal, purple, planar papules** (the "6 Ps"). - **Lichen planopilaris** (follicular variant) causes **scarring alopecia** with follicular hyperkeratosis, not annular scaly plaques. - Wickham striae may be visible on mucosal surfaces. *Pityriasis versicolor* - Caused by **Malassezia species**, presents as **hypo- or hyperpigmented macules** with fine scale on trunk and upper arms. - **Follicular variant** (pityriasis folliculorum) shows discrete follicular papules, NOT annular plaques. - "Spaghetti and meatballs" appearance on KOH prep (short hyphae and spores) differentiates from dermatophytes.

Q: An adolescent male presents with severe acne lesions and sinus tracts. Which is the most effective drug for this condition?

Isotretinoin. ***Isotretinoin*** - This patient presents with **severe acne**, likely cystic or nodular, given the mention of "sinus tracts," which often correlates with **acne conglobata**. - **Isotretinoin** is the most effective treatment for severe acne as it targets all four pathogenic factors of acne: **sebaceous gland activity**, **follicular hyperkeratinization**, *C. acnes* proliferation, and inflammation. *Minocycline* - Minocycline is an **oral antibiotic** used for moderate to severe inflammatory acne, primarily due to its anti-inflammatory properties and ability to reduce *C. acnes*. - While effective for some inflammatory acne, it is **less effective than isotretinoin** for severe, nodulocystic acne or acne with sinus tracts and is not a definitive cure. *Doxycycline* - Doxycycline is another **oral tetracycline antibiotic** commonly used for moderate to severe inflammatory acne due to its anti-inflammatory effects and reduction of *C. acnes*. - Similar to minocycline, it is a good option for inflammatory acne but **insufficient for very severe, recalcitrant acne** with sinus tracts, where isotretinoin is superior. *Topical dapsone* - Topical dapsone is an **anti-inflammatory agent** primarily used for mild to moderate inflammatory acne, particularly papules and pustules. - It is **not effective for severe nodulocystic acne** or acne associated with sinus tracts and would not be appropriate as monotherapy for this presentation.

Q: A patient presents with itchy skin lesions with blistering along with gastrointestinal issues. Which of the following is the most specific serological test for this condition?

Anti-endomysial antibody. ***Anti-endomysial antibody*** - The combination of **itchy, blistering skin lesions** and **gastrointestinal issues** is highly suggestive of **Dermatitis Herpetiformis**, which is the cutaneous manifestation of **celiac disease**. - **Anti-endomysial antibody (EMA)**, particularly IgA, is highly specific (nearly 100%) for **celiac disease** and thus for Dermatitis Herpetiformis, especially when tested on primate esophagus. *Anti-TTG antibody* - **Anti-tissue transglutaminase (tTG) antibody** (IgA) is a sensitive and specific serological marker for **celiac disease** and is often the first-line test. - While highly indicative, **EMA** is generally considered to have slightly higher specificity than tTG for celiac disease, particularly in predicting intestinal villous atrophy. *Anti-nuclear antibody* - **Anti-nuclear antibodies (ANA)** are primarily associated with **systemic autoimmune diseases** like Systemic Lupus Erythematosus. - They are not specific for **celiac disease** or **Dermatitis Herpetiformis**. *Anti-desmoglein antibody* - **Anti-desmoglein antibodies** (anti-Dsg1 and anti-Dsg3) are specific for **pemphigus vulgaris** and **pemphigus foliaceus**, which are autoimmune blistering disorders. - While these conditions present with blistering, they typically lack the gastrointestinal symptoms and the specific pruritic, grouped vesicular pattern seen in **Dermatitis Herpetiformis**. - This is not the appropriate serological test for DH/celiac disease. *IgA deposits at the dermoepidermal junction* - The presence of **granular IgA deposits at the dermoepidermal junction** (dermal papillae) is the **gold standard for diagnosing Dermatitis Herpetiformis** through **direct immunofluorescence** of a skin biopsy. - However, this is a **histopathological finding**, not a serological test, and therefore does not fit the question's criteria for a "serological test."

Q: A 27-year-old patient presents with motheaten alopecia, moist perianal lesions, and an asymptomatic macular rash. What is the most likely causative organism?

Treponema. ***Treponema*** - The constellation of **motheaten alopecia**, **moist perianal lesions** (condyloma lata), and an **asymptomatic macular rash** is highly characteristic of **secondary syphilis**, caused by *Treponema pallidum*. - **Condyloma lata** are highly infectious, raised plaques found in moist areas, and the rash can affect palms and soles. *Haemophilus* - *Haemophilus influenzae* is primarily associated with **respiratory infections** (e.g., otitis media, epiglottitis, pneumonia) and sometimes meningitis. - It does not cause the specific dermatological manifestations described in the patient. *Klebsiella* - *Klebsiella pneumoniae* is a common cause of **nosocomial infections**, particularly **pneumonia** (often with currant jelly sputum), **UTIs**, and wound infections. - It is not associated with skin conditions like alopecia or maculopapular rashes typical of syphilis. *Herpes Simplex* - Herpes Simplex Virus (HSV) causes **vesicular or ulcerative lesions**, commonly known as cold sores or genital herpes. - It does not cause motheaten alopecia, moist perianal plaques (condyloma lata), or an asymptomatic macular rash in the same manner as syphilis.

Q: A patient presents with sinus tracts on the foot, and a smear reveals filamentous organisms.

Nocardia. ***Correct: Nocardia*** - **Nocardia species** cause **actinomycetoma**, a chronic infection characterized by **sinus tracts** discharging purulent material with sulfur granules - Smear shows **branching filamentous organisms** that are gram-positive and partially acid-fast - Classic presentation: sinus tracts on foot with filamentous organisms on direct microscopy - Key features: aerobic actinomycetes, branching at acute angles (45°) *Incorrect: Sporothrix* - Causes **sporotrichosis** (lymphocutaneous nodules along lymphatics), not sinus tracts - **Dimorphic fungus** diagnosed primarily by culture, not direct smear - Clinical presentation: nodular lesions following trauma (rose gardener's disease) - Does not show filamentous organisms on direct smear *Incorrect: Dermatophytes* - Cause **superficial infections** of skin, hair, and nails (tinea pedis, ringworm) - Do not form **deep sinus tracts** or involve subcutaneous tissue - Microscopy shows septate hyphae in skin scrapings, not in discharge from sinus tracts - Clinical presentation completely different from actinomycetoma *Incorrect: Candida* - **Yeast** causing mucocutaneous infections (thrush, vaginitis) or systemic candidiasis - Does not cause **sinus tracts** on the foot - Microscopy reveals **budding yeasts and pseudohyphae**, not true branching filaments - Not associated with actinomycetoma-type presentations

Question 1

Identify the structures labeled A, B, C, and D in the given histological section of skin

Accepted Answer

A: Sebaceous gland; B: Arrector pili muscle; C: Apocrine gland; D: Eccrine gland

Answer

A: Eccrine gland; B: Arrector pili muscle; C: Sebaceous gland; D: Apocrine gland

Answer

A: Sebaceous gland; B: Apocrine gland; C: Eccrine gland; D: Arrector pili muscle

Answer

A: Apocrine gland; B: Eccrine gland; C: Sebaceous gland; D: Arrector pili muscle

Question 2

What is the period called between the entry of an organism into the host and the point of maximum infectivity?

Accepted Answer

Latent Period

Answer

Generation Time

Answer

Incubation Period

Answer

Prodromal Period

Question 3

A patient presents with loss of sensation along the ulnar nerve path. The histology is shown in the image, and a Lepromin test was performed. What is the expected outcome?

Accepted Answer

Tuberculoid leprosy with lepromin positive

Answer

Borderline leprosy with lepromin positive

Answer

Lepromatous leprosy with lepromin positive

Answer

Scrofuloderma

Question 4

A patient's skin biopsy shows a box-shaped or square-shaped pattern of inflammatory infiltrate, as shown in the image. What is the most likely diagnosis?

Accepted Answer

Lichen planus

Answer

Lichen amyloidosis

Answer

Morphea

Answer

Lichen nitidus

Question 5

A patient presents with orange-hued skin lesions and hyperkeratotic palms and soles. A biopsy shows alternating parakeratosis and orthokeratosis. What is the most likely diagnosis?

Accepted Answer

Pityriasis rubra pilaris

Answer

Follicular psoriasis

Answer

Keratosis follicularis

Answer

Ichthyosis vulgaris

Question 6

A patient presents with annular, scaly plaques with perifollicular extension on the trunk. What is the most likely diagnosis?

Accepted Answer

Tinea

Answer

Psoriasis

Answer

Lichen planus

Answer

Pityriasis versicolor

Question 7

An adolescent male presents with severe acne lesions and sinus tracts. Which is the most effective drug for this condition?

Accepted Answer

Isotretinoin

Answer

Minocycline

Answer

Doxycycline

Answer

Topical dapsone

Question 8

A patient presents with itchy skin lesions with blistering along with gastrointestinal issues. Which of the following is the most specific serological test for this condition?

Accepted Answer

Anti-endomysial antibody

Answer

Anti-TTG antibody

Answer

Anti-nuclear antibody

Answer

IgA deposits at the dermoepidermal junction

Answer

Anti-desmoglein antibody

Question 9

A 27-year-old patient presents with motheaten alopecia, moist perianal lesions, and an asymptomatic macular rash. What is the most likely causative organism?

Accepted Answer

Treponema

Answer

Haemophilus

Answer

Klebsiella

Answer

Herpes Simplex

Question 10

A patient presents with sinus tracts on the foot, and a smear reveals filamentous organisms.

Accepted Answer

Nocardia

Answer

Sporothrix

Answer

Dermatophytes

Answer

Candida

NEET-PG 2024

Anatomy

Community Medicine

Dermatology

Internal Medicine

Microbiology