Differential Diagnosis Development — MCQs

10 questions

Which of the following is not a differential diagnosis of non-accidental injury?

A 41 year old married female presented with headache for the last 6 months. She had several consultations. All her investigations were found to be within normal limits. She still insists that there is something wrong in her head and seeks another consultation. The most likely diagnosis is:

Choose the best method of diagnosis for the clinical sign represented in the image.

The Confusion Assessment Method (CAM) is used for which of the following?

Which of the following is not a cognitive error or dysfunction?

Statement 1 - A 59-year-old patient presents with flaccid bullae. Histopathology shows a suprabasal acantholytic split. Statement 2 - The row of tombstones appearance is diagnostic of Pemphigus vulgaris.

Radiation-induced necrosis can be diagnosed by:

Gene not involved in SCID:

Common differential diagnosis of verrucous carcinoma is -

Q10

In the evaluation of a newly diagnosed case of acute lymphoid leukemia (ALL), which of the following tests is not routinely included?

Differential Diagnosis Development Indian Medical PG Practice Questions and MCQs

Question 1: Which of the following is not a differential diagnosis of non-accidental injury?

A. Osteogenesis imperfecta
B. Scurvy
C. Caffey's disease
D. Osteopetrosis (Correct Answer)

Explanation: ***Correct: Osteopetrosis*** - Osteopetrosis is a rare genetic disorder characterized by **increased bone density** due to defective osteoclast function - While it causes bones to be brittle and prone to fracture, it has **distinctive radiological features** including diffuse sclerosis and "bone-within-bone" appearance - The **increased bone density on X-ray** is pathognomonic and readily distinguishes it from NAI, making it **less likely to be confused** with non-accidental injury in clinical practice - Fractures occur but the radiological pattern is diagnostic of the underlying metabolic bone disease *Incorrect: Osteogenesis imperfecta* - This is a **classic differential** for NAI causing **multiple brittle bone fractures** that can be mistaken for abuse - Features include **blue sclera**, **dentinogenesis imperfecta**, **wormian bones**, and **family history** - Often presents with multiple fractures at different stages of healing, mimicking the pattern seen in NAI *Incorrect: Scurvy* - Caused by **vitamin C deficiency**, leads to defective collagen synthesis - Results in **subperiosteal hemorrhages**, **metaphyseal fractures**, and **periosteal elevation** that closely mimic NAI - Additional features include **gingival bleeding**, **petechiae**, **follicular hyperkeratosis**, and **poor wound healing** *Incorrect: Caffey's disease* - Also known as **infantile cortical hyperostosis**, presents in infants under 6 months - Causes **periosteal reactions**, **bone thickening**, and **soft tissue swelling** in long bones, ribs, and mandible - The periosteal new bone formation can be mistaken for healing fractures from NAI, making it an important differential

Question 2: A 41 year old married female presented with headache for the last 6 months. She had several consultations. All her investigations were found to be within normal limits. She still insists that there is something wrong in her head and seeks another consultation. The most likely diagnosis is:

A. Illness Anxiety Disorder (Correct Answer)
B. Phobia
C. Psychogenic headache
D. Depression

Explanation: ***Illness Anxiety Disorder*** - This patient exhibits persistent **preoccupation with having a serious illness** despite **repeated medical evaluations** showing no underlying pathology. - She continues to **seek multiple consultations**, demonstrating **excessive health-related behaviors** characteristic of health anxiety. - Despite reassurance and normal investigations, she **insists something is wrong**, which is the core feature of this disorder. - Note: The presence of headache doesn't exclude this diagnosis; the key is the **disproportionate anxiety and health-seeking behavior** relative to the symptom. *Phobia* - Phobias involve an **intense, irrational fear** of a specific object or situation (e.g., agoraphobia, social phobia). - The patient's concern is about having an illness and physical symptoms, not a fear of a specific trigger or situation. *Psychogenic headache* - This is a **symptom description**, not a psychiatric disorder diagnosis. - While the headache may have psychological factors, the question asks for the **disorder** that best explains the overall clinical picture. - The primary pathology here is the **persistent health anxiety and reassurance-seeking behavior**, not just the headache itself. *Depression* - Although **depression can present with somatic symptoms** like headaches, the **core features of major depression** are not mentioned (e.g., persistent low mood, anhedonia, sleep/appetite changes, hopelessness). - The patient's **preoccupation with having a disease** despite medical reassurance is more characteristic of Illness Anxiety Disorder than depression alone.

Question 3: Choose the best method of diagnosis for the clinical sign represented in the image.

A. Serum copper
B. Serum ceruloplasmin (Correct Answer)
C. Karyotyping
D. PCR

Explanation: ***Serum ceruloplasmin*** - The image shows a **Kayser-Fleischer ring**, a greenish-brown discoloration in the periphery of the cornea, which is pathognomonic for **Wilson's disease**. - **Wilson's disease** is a genetic disorder of copper metabolism characterized by **low serum ceruloplasmin** levels (the primary copper-carrying protein in the blood) and increased copper deposition in various tissues. *Serum copper* - While Wilson's disease involves copper accumulation, **total serum copper** can be normal or even elevated due to widespread tissue damage releasing copper into the circulation, making it an unreliable diagnostic marker on its own. - A low serum copper level can be seen, but it is not as specific as low ceruloplasmin, as much of the copper in serum is bound to ceruloplasmin. *Karyotyping* - **Karyotyping** is used to analyze the number and structure of chromosomes and is primarily indicated for diagnosing chromosomal abnormalities, such as Down syndrome or Turner syndrome. - It is not relevant for diagnosing metabolic disorders like Wilson's disease, which is caused by a mutation in a single gene (ATP7B), not a chromosomal aberration. *PCR* - **PCR (Polymerase Chain Reaction)** is a technique used to amplify DNA sequences and can be used for genetic testing to identify specific mutations. - While genetic testing for the **ATP7B gene** mutation is a confirmatory test for Wilson's disease, it is not the primary or best method for initial diagnosis, especially when classic clinical signs and biochemical markers (like low ceruloplasmin) are present.

Question 4: The Confusion Assessment Method (CAM) is used for which of the following?

A. Schizophrenia
B. Delirium (Correct Answer)
C. Dementia
D. Depression

Explanation: ***Delirium*** - The Confusion Assessment Method (CAM) is a widely used and highly sensitive and specific tool for the rapid identification of **delirium**. - It assesses for acute onset and fluctuating course, inattention, disorganized thinking, and altered level of consciousness. *Schizophrenia* - Schizophrenia is a chronic mental health disorder primarily characterized by **psychosis**, including hallucinations, delusions, and disorganized thought. - While patients with schizophrenia can experience cognitive difficulties, specialized scales like the Positive and Negative Syndrome Scale (PANSS) are used, not the CAM. *Dementia* - Dementia is a gradual and progressive decline in cognitive function, including memory, thinking, and reasoning, severe enough to interfere with daily life. - Tools like the mini-mental state examination (MMSE) or Montreal Cognitive Assessment (MoCA) are used for screening and assessing dementia, not the CAM. *Depression* - Depression is a mood disorder characterized by persistent sadness, loss of interest, and other emotional and physical symptoms. - Assessment tools like the Hamilton Depression Rating Scale (HDRS) or Patient Health Questionnaire-9 (PHQ-9) are used for depression.

Question 5: Which of the following is not a cognitive error or dysfunction?

A. Arbitrary inference
B. Overgeneralization
C. Catastrophic thinking
D. Thought block (Correct Answer)

Explanation: ***Thought block*** - **Thought block** is a **formal thought disorder**, not a cognitive error or cognitive distortion - It involves a **sudden interruption in the stream of thought**, where the person experiences an abrupt cessation of thinking and speech - This is a **primary thought disorder** commonly associated with schizophrenia and other psychotic conditions - Unlike cognitive errors which involve **distorted interpretations**, thought block is a **disruption in the thought process itself** *Catastrophic thinking* - This IS a **cognitive error** (cognitive distortion) where individuals anticipate the **worst possible outcome** - Involves blowing small problems out of proportion in an exaggerated or unrealistic way - Common in anxiety and depressive disorders - Part of Beck's cognitive distortions framework *Arbitrary inference* - This IS a **cognitive error** where individuals draw **conclusions without sufficient evidence** or despite contradictory evidence - Involves making negative interpretations without logical support - Example: "My friend didn't call me back, so she must hate me" - Part of Beck's cognitive therapy model *Overgeneralization* - This IS a **cognitive error** where individuals draw **broad, sweeping negative conclusions** based on a single event - If one negative event occurs, the person believes it will happen repeatedly forever - Example: "I failed this test, so I'll fail all my exams" - Common cognitive distortion in depression

Question 6: Statement 1 - A 59-year-old patient presents with flaccid bullae. Histopathology shows a suprabasal acantholytic split. Statement 2 - The row of tombstones appearance is diagnostic of Pemphigus vulgaris.

A. Statements 1 & 2 are correct, 2 is not explaining 1 (Correct Answer)
B. Statements 1 and 2 are correct and 2 is the correct explanation for 1
C. Statements 1 and 2 are incorrect
D. Statement 1 is incorrect

Explanation: ***Correct: Statements 1 & 2 are correct, 2 is not explaining 1*** **Analysis of Statement 1:** - A 59-year-old patient with **flaccid bullae** and **suprabasal acantholytic split** on histopathology is the classic presentation of **Pemphigus vulgaris** - The flaccid (easily ruptured) nature of bullae distinguishes it from tense bullae seen in bullous pemphigoid - The suprabasal location of the split (just above the basal layer) with acantholysis (loss of cell-to-cell adhesion) is pathognomonic - **Statement 1 is CORRECT** ✓ **Analysis of Statement 2:** - The **"row of tombstones" or "tombstone appearance"** is indeed a diagnostic histopathological feature of Pemphigus vulgaris - This appearance results from basal keratinocytes remaining attached to the basement membrane while suprabasal cells separate due to acantholysis - The intact basal cells standing upright resemble a row of tombstones - **Statement 2 is CORRECT** ✓ **Does Statement 2 explain Statement 1?** - Statement 2 describes a **histopathological appearance** (tombstone pattern) that is a **consequence** of the suprabasal split - However, it does NOT explain the **underlying cause** of the flaccid bullae or the suprabasal split - The true explanation involves **IgG autoantibodies against desmoglein 3 (and desmoglein 1)**, which attack intercellular adhesion structures (desmosomes), causing **acantholysis** - Therefore, **Statement 2 does NOT explain Statement 1** ✗ *Incorrect: Statement 2 is the correct explanation for Statement 1* - While both statements describe features of Pemphigus vulgaris, the tombstone appearance is a descriptive finding, not an explanatory mechanism *Incorrect: Statements 1 and 2 are incorrect* - Both statements are medically accurate descriptions of Pemphigus vulgaris features *Incorrect: Statement 1 is incorrect* - Statement 1 correctly describes the cardinal clinical and histopathological features of Pemphigus vulgaris

Question 7: Radiation-induced necrosis can be diagnosed by:

A. MRI
B. CT
C. PET
D. Biopsy (Correct Answer)

Explanation: ***Biopsy*** - A **biopsy** is the definitive diagnostic method for radiation-induced necrosis, allowing for histological examination of tissue to confirm necrosis and rule out residual or recurrent tumor. [1], [2] - It provides a direct view of cellular changes, identifying **necrosis, atypical cells**, and ruling out **malignancy**. *MRI* - While **MRI** can show structural changes indicative of necrosis (e.g., mass effect, edema), it often cannot definitively differentiate between **radiation necrosis** and **tumor recurrence.** [2] - It often shows **T1 hypointensity** and **T2 hyperintensity**, but these findings are not specific. *CT* - **CT scans** are useful for detecting gross changes like **mass effect** and **edema** but have limited sensitivity for distinguishing necrosis from tumor recurrence. - It may show **low-density lesions** but lacks the resolution and specificity for precise diagnosis. *PET* - **PET scans** measure metabolic activity and can help distinguish between **tumor recurrence** (high uptake) and **radiation necrosis** (low uptake) in some cases. - However, false positives can occur, as some inflammatory processes in necrosis can also show increased uptake, making it **less definitive** than a biopsy. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Central Nervous System, pp. 1307-1308. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Neoplasia, pp. 340-341.

Question 8: Gene not involved in SCID:

A. BTK (Correct Answer)
B. ZAP70
C. IL2RG
D. JAK3

Explanation: ***BTK*** - **Bruton's tyrosine kinase (BTK)** is associated with **X-linked agammaglobulinemia (XLA)**, a primary immunodeficiency characterized by the absence of B cells and low immunoglobulin levels, not SCID [1]. - Individuals with XLA have recurrent bacterial infections but typically have intact T-cell immunity, differentiating it from SCID [1]. *ZAP70* - Mutations in the **ZAP70 gene** lead to a form of **SCID** characterized by an absence of CD8+ T cells and non-functional CD4+ T cells. - ZAP70 is critical for signal transduction from the T cell receptor, and its deficiency severely impairs T-cell development and function. *IL2RG* - The **IL2RG gene** encodes the **common gamma chain (γc)**, a shared component of several interleukin receptors (e.g., IL-2, IL-4, IL-7, IL-9, IL-15, IL-21) [1]. - Mutations in IL2RG cause **X-linked severe combined immunodeficiency (X-SCID)**, the most common form of SCID, leading to a profound defect in T-cell and NK-cell development [1]. *JAK3* - **JAK3** is a tyrosine kinase that associates with the common gamma chain (γc) and plays a crucial role in signaling downstream of cytokine receptors [1]. - Defects in **JAK3** lead to an **autosomal recessive form of SCID** that phenocopies X-SCID, with impaired T-cell and NK-cell development due to disrupted cytokine signaling [1]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of the Immune System, pp. 247-249.

Question 9: Common differential diagnosis of verrucous carcinoma is -

A. Adenocarcinoma
B. Tuberculosis
C. Condylomata lata
D. Condylomata acuminata (Correct Answer)

Explanation: ***Condylomata acuminata*** - **Verrucous carcinoma** is a rare, well-differentiated squamous cell carcinoma that often presents as a large, exophytic, warty mass, making it clinically similar to **condylomata acuminata (genital warts)** [1]. - Both conditions can appear as **cauliflower-like lesions** on mucosal surfaces, especially in the anogenital region, necessitating **biopsy** for definitive differentiation [1]. *Adenocarcinoma* - **Adenocarcinoma** typically arises from glandular tissue and presents as a mass or ulcer, but rarely as a **verrucous (warty)** lesion [2]. - Its histological features, characterized by **glandular differentiation**, are distinct from the acanthotic, hyperkeratotic pattern of verrucous carcinoma [2]. *Tuberculosis* - **Tuberculosis** can cause granulomatous lesions, but these are typically **ulcerative** or **nodular**, rather than large, exophytic, warty growths characteristic of verrucous carcinoma. - Diagnosis involves identifying **acid-fast bacilli** and characteristic granulomas with caseous necrosis, which are absent in verrucous carcinoma. *Condylomata lata* - **Condylomata lata** are broad, flat, moist papules associated with **secondary syphilis**, which are distinct from the exophytic, warty appearance of verrucous carcinoma [3]. - These lesions are typically **non-pruritic** and reveal spirochetes on dark-field microscopy, unlike verrucous carcinoma [3]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Lower Urinary Tract and Male Genital System, pp. 974-975. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Lower Urinary Tract and Male Genital System, pp. 973-974. [3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Female Genital Tract, pp. 1000-1002.

Question 10: In the evaluation of a newly diagnosed case of acute lymphoid leukemia (ALL), which of the following tests is not routinely included?

A. Plasma viscosity (Correct Answer)
B. Bone marrow biopsy
C. Complete metabolic panel
D. Cell surface phenotyping

Explanation: ### Plasma viscosity - **Plasma viscosity** measurement is not a standard diagnostic or staging test for **acute lymphoid leukemia (ALL)**. [1] - While it can be elevated in conditions with high protein levels or hypergammaglobulinemia, it does not provide specific information relevant to ALL diagnosis or treatment planning. [1] *Bone marrow biopsy* - A **bone marrow biopsy** is crucial for diagnosing ALL, confirming the presence of **lymphoblasts**, and assessing disease burden. [2] - It also helps in identifying cytogenetic and molecular abnormalities. [2] *Cell surface phenotyping* - **Cell surface phenotyping** (immunophenotyping) via **flow cytometry** is essential for classifying the subtype of ALL (e.g., B-ALL, T-ALL) and identifying specific markers. [2] - This information guides treatment protocols and predicts prognosis. [2] *Complete metabolic panel* - A **complete metabolic panel (CMP)** assesses organ function (e.g., kidney, liver), **electrolyte balance**, and levels of substances like **uric acid** and **lactate dehydrogenase (LDH)**. - These measurements are vital for identifying complications, assessing baseline health, and monitoring for **tumor lysis syndrome** which can be seen in ALL.

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