Bone and Soft Tissue Pathology Practice Questions

Q: Which of the following are seen in rickets?

Defective mineralization. **Explanation:** The core pathology of **Rickets** is the failure of osteoid to mineralize. Rickets occurs in the growing bones of children (before epiphyseal closure) and is characterized by an accumulation of unmineralized matrix at the growth plate. * **Why Option B is Correct:** In Rickets, there is a deficiency of Calcium or Phosphate (often due to Vitamin D deficiency). This leads to **defective mineralization** of the newly formed osteoid at the zone of provisional calcification. This results in the expansion of the growth plate and the characteristic skeletal deformities. * **Why Option A is Incorrect:** While **cupping, splaying, and fraying** of the metaphysis are classic *radiological* features of rickets, the question asks for the underlying pathological process. Cupping is a sign, whereas defective mineralization is the fundamental mechanism. * **Why Option C is Incorrect:** **Epiphyseal dysgenesis** (fragmented, "stippled" epiphysis) is a hallmark of **Hypothyroidism** (Cretinism), not rickets. In rickets, the epiphyses are often delayed in appearance or blurred, but not dysgenetic. * **Why Option D is Incorrect:** **Defective osteoid formation** is the hallmark of **Scurvy** (Vitamin C deficiency). In Scurvy, the mineralizing mechanism is intact, but the collagen/osteoid matrix itself is not produced correctly. **High-Yield Pearls for NEET-PG:** * **Earliest Clinical Sign:** Craniotabes (softening of skull bones). * **Earliest Radiological Sign:** Fraying and cupping of the distal ends of the radius and ulna. * **Biochemical Profile:** Low/Normal Calcium, Low Phosphate, and **Elevated Alkaline Phosphatase (ALP)**—ALP is the best marker for disease activity. * **Rachitic Rosary:** Palpable beads at the costochondral junctions (rounded in rickets, sharp/angular in the "Scorbutic rosary" of Scurvy).

Q: What is the most common cause of osteoblastic bone metastasis in females?

Breast cancer. **Explanation:** **1. Why Breast Cancer is Correct:** In females, **breast cancer** is the most common primary malignancy to metastasize to the bone [1]. While breast cancer often produces mixed (osteolytic and osteoblastic) lesions, it is the **most frequent cause of osteoblastic (sclerotic) metastases in women**. This occurs because tumor cells secrete factors like Bone Morphogenetic Proteins (BMPs) and TGF-β, which stimulate osteoblast proliferation and new bone formation. **2. Why Other Options are Incorrect:** * **Cervical Cancer:** While it can spread to pelvic bones, it is a much less common cause of bone metastasis compared to breast cancer and typically presents as osteolytic lesions. * **Thyroid Cancer:** Follicular thyroid carcinoma frequently metastasizes to bone [1], but these lesions are characteristically **purely osteolytic** and often "pulsatile" in nature. * **Osteosarcoma:** This is a primary bone tumor, not a metastatic process from another organ [2]. While it produces osteoid (bone), it does not fit the category of "metastasis" in this context. **3. High-Yield NEET-PG Pearls:** * **Most common cause of osteoblastic metastasis (Overall & Males):** Prostate Cancer (presents with elevated Serum Acid Phosphatase and PSA) [1]. * **Most common cause of osteolytic metastasis (Adults):** Lung Cancer and Multiple Myeloma [1]. * **Most common site for bone metastasis:** Spine (Vertebrae), followed by the femur and pelvis. * **Imaging Gold Standard:** Bone scan (Technetium-99m) is highly sensitive for osteoblastic activity, whereas PET scans or MRI are better for purely lytic lesions like Myeloma. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Osteoarticular And Connective Tissue Disease, pp. 671-674. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Osteoarticular And Connective Tissue Disease, pp. 673-674.

Q: In the alveolar variant of rhabdomyosarcoma, the resultant fusion protein is believed to function as what?

Chimeric transcription factor. **Explanation:** The correct answer is **B. Chimeric transcription factor.** **Understanding the Mechanism:** Alveolar Rhabdomyosarcoma (ARMS) is characterized by specific chromosomal translocations, most commonly **t(2;13)(q35;q14)** and less frequently **t(1;13)(p36;q14)**. These translocations result in the fusion of the **PAX3** (or PAX7) gene with the **FOXO1** (formerly FKHR) gene. * **PAX3/7** are genes involved in muscle differentiation (transcription factors). * **FOXO1** is a transcription factor involved in cell cycle regulation. The resulting **PAX3-FOXO1** fusion protein is a **chimeric transcription factor**. It possesses the DNA-binding domain of PAX and the transactivation domain of FOXO1, making it a much more potent activator of myogenic genes than wild-type PAX3. This leads to dysregulated gene expression, promoting cell proliferation and inhibiting apoptosis. **Analysis of Incorrect Options:** * **A & D (Growth Factor/Receptor):** While many cancers (like GIST or HER2+ breast cancer) involve growth factors or their receptors, ARMS is driven by nuclear genetic rearrangement, not extracellular signaling molecules. * **C (Constitutively active kinase):** This mechanism is classic for **Chronic Myeloid Leukemia (BCR-ABL)**, where the fusion protein acts as a tyrosine kinase. In ARMS, the fusion protein acts directly on DNA in the nucleus. **High-Yield Clinical Pearls for NEET-PG:** * **Embryonal RMS:** Most common type; associated with **loss of heterozygosity (LOH) at 11p15.5** (IGF-2 gene). * **Alveolar RMS:** More aggressive; characterized by **t(2;13)** fusion. * **Histology:** ARMS shows small round blue cells arranged in clusters separated by fibrous septa, resembling pulmonary alveoli. * **IHC Markers:** Desmin, Myogenin (Myf4), and MyoD1 are positive. Myogenin expression is typically more diffuse in the Alveolar variant compared to the Embryonal variant.

Q: Peripheral giant cell granuloma occurs most commonly on which of the following locations?

Gingiva. **Explanation:** **Peripheral Giant Cell Granuloma (PGCG)** is a common reactive exophytic lesion of the oral cavity, representing a local response to chronic irritation or trauma. 1. **Why Gingiva is Correct:** The PGCG originates specifically from the **periosteum or the periodontal ligament**. Because these tissues are anatomically associated with the tooth-bearing areas, the lesion occurs exclusively on the **gingiva** (usually the interdental papilla) or the edentulous **alveolar ridge**. Between the two, the gingiva is the most frequent site of involvement. 2. **Why Other Options are Incorrect:** * **Alveolar Ridge:** While PGCG can occur here in edentulous patients, it is statistically less common than the gingival presentation in dentate individuals. * **Palate and Floor of the Mouth:** These sites lack the periodontal ligament and the specific periosteal environment required for PGCG formation. Lesions found here are more likely to be Pyogenic Granulomas or Irritation Fibromas. **High-Yield Clinical Pearls for NEET-PG:** * **Clinical Appearance:** It typically presents as a firm, reddish-blue or "liver-colored" nodule. The dark color is due to prominent vascularity and hemorrhage. * **Histopathology:** Characterized by a non-encapsulated proliferation of **multinucleated giant cells** in a background of ovoid to spindle-shaped mesenchymal cells, with prominent **hemosiderin deposits**. * **Radiology:** While "peripheral" (soft tissue), it may cause "cupping" or superficial resorption of the underlying alveolar bone. * **Differential Diagnosis:** Must be distinguished from **Central Giant Cell Granuloma (CGCG)**, which is an intraosseous lesion, and the "Brown Tumor" of hyperparathyroidism (biochemical correlation with Serum Calcium/PTH is essential).

Question 1

All of the following lesions may be classified as odontogenic tumours EXCEPT?

Accepted Answer

Branchial cleft cyst

Answer

Acanthomatous ameloblastoma

Answer

Myxoma

Answer

Simple ameloblastoma

Question 2

Which of the following are seen in rickets?

Accepted Answer

Defective mineralization

Answer

Cupping of the metaphysis

Answer

Epiphyseal dysgenesis

Answer

Defective osteoid formation

Question 3

A 25-year-old male is diagnosed with osteosarcoma involving his right femur. Mutation of which of the following genes can be related to the development of osteosarcoma?

Accepted Answer

RB gene

Answer

APC gene

Answer

Bcl-2 gene

Answer

c-myc gene

Question 4

Which one of the following soft tissue sarcomas frequently metastasizes to lymph nodes?

Accepted Answer

Embryonal rhabdomyosarcoma

Answer

Fibrosarcoma

Answer

Osteosarcoma

Answer

Alveolar soft part sarcoma

Question 5

Ewing's sarcoma is associated with which marker?

Accepted Answer

CD-56

Answer

CD-38

Answer

CD-117

Answer

CD-139

Question 6

Which of the following statements is NOT TRUE about synovial sarcoma?

Accepted Answer

It is seen in individuals over 50 years of age.

Answer

It does not arise from synovium.

Answer

It occurs more commonly at extra-articular sites.

Answer

Knee and foot are common sites involved.

Question 7

What is the most common cause of osteoblastic bone metastasis in females?

Accepted Answer

Breast cancer

Answer

Cervical cancer

Answer

Thyroid cancer

Answer

Osteosarcoma

Question 8

In the alveolar variant of rhabdomyosarcoma, the resultant fusion protein is believed to function as what?

Accepted Answer

Chimeric transcription factor

Answer

Activated growth factor receptor

Answer

Constitutively active kinase

Answer

Novel growth factor

Question 9

Synovial sarcomas typically spread by which route?

Accepted Answer

Lymphatic route

Answer

Hematogenous route

Answer

Drop metastasis

Answer

It does not metastasize; it is a locally invasive tumor

Question 10

Peripheral giant cell granuloma occurs most commonly on which of the following locations?

Accepted Answer

Gingiva

Answer

Alveolar ridge

Answer

Palate

Answer

Floor of the mouth

Bone and Soft Tissue Pathology — MCQs

Bone and Soft Tissue Pathology — MCQs

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