General Pathology Practice Questions

Q: Which of the following statements about Becker muscular dystrophy is FALSE?

The gene involved is for myosin.. **Explanation:** The correct answer is **C** because Becker Muscular Dystrophy (BMD) is caused by a mutation in the **dystrophin gene** (located on the short arm of the X chromosome, Xp21), not the myosin gene [1]. Dystrophin is a vital structural protein that links the intracellular cytoskeleton (actin) to the extracellular matrix, stabilizing the sarcolemma during muscle contraction. * **Option A is true:** BMD follows an **X-linked recessive** inheritance pattern, primarily affecting males while females are typically asymptomatic carriers [2]. * **Option B is true:** BMD is characterized by **slowly progressive** proximal muscle weakness. Unlike Duchenne Muscular Dystrophy (DMD), patients with BMD often remain ambulatory well into their 20s or later. * **Option D is true:** DMD is more severe because it results from **frameshift mutations** leading to a near-total absence of dystrophin [1]. In contrast, BMD results from **non-frameshift (in-frame) mutations**, leading to the production of a truncated but partially functional dystrophin protein [1]. **NEET-PG High-Yield Pearls:** * **Genetic Locus:** The dystrophin gene is the largest known human gene, making it highly susceptible to spontaneous mutations. * **Clinical Sign:** Both DMD and BMD may present with **pseudohypertrophy of the calves** (fatty replacement of muscle). * **Diagnosis:** Gold standard is genetic testing; muscle biopsy shows diminished (not absent) dystrophin staining in BMD. * **Cardiac Involvement:** Dilated cardiomyopathy is a common cause of mortality in both conditions. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Peripheral Nerves and Skeletal Muscles, pp. 1244-1246. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Genetic Disorders, p. 151.

Q: Which stain is used for melanin?

Masson Fontana stain. **Explanation:** The correct answer is **Masson Fontana stain**. **1. Why Masson Fontana is correct:** Melanin is a non-lipid, non-hematogenous pigment produced by melanocytes [1]. It possesses **argentaffin** properties, meaning it has the inherent ability to reduce silver nitrate to metallic silver without the need for an external reducing agent. The Masson Fontana stain utilizes this property; the silver salts are reduced by melanin, resulting in a distinct **black** coloration of the pigment granules. **2. Analysis of Incorrect Options:** * **Alizarin red S:** This is a specialized stain used to identify **calcium** deposits. It reacts with calcium to form an orange-red lake. * **Von Kossa:** This is another method for **calcium** (specifically phosphates and carbonates). It is a metal substitution method where silver replaces calcium, appearing as black deposits. * **PAS (Periodic Acid-Schiff) stain:** This stain is primarily used to demonstrate **glycogen, mucopolysaccharides, and basement membranes**. It stains these structures magenta/bright pink. It is also the stain of choice for identifying fungal cell walls. **3. NEET-PG High-Yield Pearls:** * **Bleaching Test:** To confirm a pigment is melanin, "Melanin Bleaching" is performed using hydrogen peroxide or potassium permanganate. Melanin disappears, whereas other pigments like lipofuscin do not. * **Schmorl’s Reaction:** Another method used for melanin (and lipofuscin), which produces a blue-green color. * **DOPA Reaction:** Used to identify the enzyme tyrosinase in fresh tissue to confirm melanocytic activity. * **Iron Stain:** To differentiate melanin from hemosiderin (which looks similar), use **Prussian Blue (Perl’s stain)**; it stains hemosiderin blue but does not react with melanin. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Blood And Bone Marrow Disease, pp. 633-634.

Q: Identify the rosette and its corresponding diagnosis.

Perivascular pseudorosette. ***Perivascular pseudorosette*** - Characterized by **radial arrangement** of tumor cells around blood vessels with **fibrillary processes** extending toward the vessel wall, creating a perivascular pattern. - **Pathognomonic** for **ependymoma**, a glial tumor arising from ependymal cells lining the ventricles and central canal of the spinal cord. *Homer Wright rosette* - Features tumor cells arranged in a **circular pattern** around a **central tangle of neural filaments** without a true lumen. - Classically associated with **neuroblastoma** and **medulloepithelioma**, but not diagnostic as they can be seen in other neural tumors. *True rosette* - Contains a **central true lumen** lined by tumor cells, representing primitive neural tube formation. - Seen in **primitive neuroectodermal tumors (PNET)** and **medulloepithelioma**, but less specific than other rosette types. *Flexner Wintersteiner rosette* - Shows tumor cells arranged around a **central lumen** with terminal bars and **internal limiting membrane**, resembling retinal photoreceptors. - **Pathognomonic** for **retinoblastoma**, the most common primary intraocular malignancy in children.

Question 1

Which of the following statements about Becker muscular dystrophy is FALSE?

Accepted Answer

The gene involved is for myosin.

Answer

It is an X-linked recessive inherited disorder.

Answer

It is characterized by slowly progressive muscle weakness of the legs and pelvis.

Answer

Duchenne muscular dystrophy is much more severe than Becker muscular dystrophy.

Question 2

All of the following are opsonins, except?

Accepted Answer

LTB4

Answer

IgG

Answer

C3b

Answer

Mannose binding lectin

Question 3

Amyloid material can be best diagnosed by which method?

Accepted Answer

Polarized microscopy

Answer

Electron microscopy

Answer

X-ray crystallography

Answer

Scanning electron microscopy

Question 4

Yellow or green pigmentation of teeth is seen in which of the following conditions?

Accepted Answer

Erythroblastosis fetalis

Answer

Porphyria

Answer

Internal resorption

Answer

Nasmyth membrane

Question 5

Which stain is used for melanin?

Accepted Answer

Masson Fontana stain

Answer

Alizarin red S

Answer

Von Kossa

Answer

PAS stain

Question 6

Common variable hypogammaglobulinemia shows which of the following?

Accepted Answer

Normal B cell count

Answer

Decreased B cell count

Answer

Increased B cell count

Answer

Absent B cells

Question 7

Secondary amyloidosis is seen most commonly in which of the following conditions?

Accepted Answer

Tuberculosis

Answer

Actinomycosis

Answer

Rabies

Answer

Secondary syphilis

Question 8

Which of the following conditions can present with numbness of the lip in the absence of previous dental treatment?

Accepted Answer

Metastatic carcinoma

Answer

Central nervous system lesion

Answer

Osteomyelitis

Answer

Infection

Question 9

Which proto-oncogene is involved in Gastrointestinal Stromal Tumors (GIST)?

Accepted Answer

KIT

Answer

RAS

Answer

RET

Answer

MYC

Question 10

Identify the rosette and its corresponding diagnosis.

Accepted Answer

Perivascular pseudorosette

Answer

Homer Wright rosette

Answer

True rosette

Answer

Flexner Wintersteiner rosette

General Pathology — MCQs

General Pathology — MCQs

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