Bone and Soft Tissue Pathology — MCQs

A 50-year-old woman presents with a painless soft tissue mass in her right thigh. Upon surgical excision, the surgeon notices that the tumor is adherent to the surrounding tissues. Histologic analysis reveals a neoplasm composed of pleomorphic clear cells, with vacuolated cytoplasm. The nucleus of many cells is indented by the cytoplasmic vacuoles, which are stained by histochemical methods for lipids. Which of the following is the most likely diagnosis?

Q224Easy

Decreased mineralization of the epiphyseal plate in a growing child is seen in which condition?

Q225Medium

A 25-year-old male patient presents with a bony expansile swelling of the right body of the mandible and mild paresthesia of the right inferior dental nerve. OPG shows a multilocular radiolucency without root resorption. What is odontogenic keratocyst noted for?

Q226Easy

Rickets is characterized by what?

Q227Medium

Histology of a biopsy from a long bone is shown below. Which of the following is the likely diagnosis?

Q228Easy

Which of the following are common primary sites of metastasis to the brain?

Q229Easy

What is the gene responsible for Van der Woude syndrome?

Q230Easy

Bone dysplasia is invariably seen in which of the following?

Bone and Soft Tissue Pathology Indian Medical PG Practice Questions and MCQs

Question 221: Which of the following is NOT associated with Paget's disease of bone?

A. Virus association
B. Progression to chondrosarcoma
C. Malignant transformation in less than 1% of cases (Correct Answer)
D. Osteosclerotic phase is seen

Explanation: Paget’s Disease of Bone (Osteitis Deformans) is a chronic disorder characterized by disordered bone remodeling, resulting in thickened but structurally weak bone. **Why Option C is the correct answer (The "NOT" association):** While the majority of Paget’s disease cases remain benign, malignant transformation (Paget’s sarcoma) occurs in approximately **1% to 5%** of patients with extensive polyostotic disease. The option stating it occurs in "less than 1%" is statistically inaccurate for clinically significant, symptomatic cases, making it the least correct association in the context of standard pathology textbooks (like Robbins). **Analysis of Incorrect Options:** * **A. Virus association:** There is a strong hypothesis linking Paget’s to a slow virus infection, specifically **Paramyxoviruses** (like Measles or Respiratory Syncytial Virus) [2]. Nucleocapsid-like particles are often seen in the osteoclasts. * **B. Progression to chondrosarcoma:** While **Osteosarcoma** is the most common malignancy arising from Paget’s, other sarcomas including **Chondrosarcoma** and Fibrosarcoma can also occur. * **D. Osteosclerotic phase is seen:** Paget’s progresses through three distinct phases: 1) An initial **Osteolytic** phase, 2) A mixed phase, and 3) A final **Osteosclerotic** (burnt-out) phase characterized by dense, mineralized bone. **High-Yield Clinical Pearls for NEET-PG:** * **Hallmark Pathology:** The "Mosaic pattern" of lamellar bone with prominent cement lines (Jigsaw puzzle appearance). * **Biochemical Marker:** Isolated elevation of **Serum Alkaline Phosphatase (ALP)** with normal Calcium and Phosphate levels. * **Clinical Signs:** Increasing hat size, "Lion-like" facies (leontiasis ossea), and sensorineural hearing loss due to nerve compression in the skull [2]. * **Treatment:** Bisphosphonates are the mainstay of therapy [1]. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Osteoarticular And Connective Tissue Disease, pp. 670-671. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Bones, Joints, and Soft Tissue Tumors, pp. 1191-1194.

Question 222: Which of the following statements regarding glomus tumors is not true?

A. It is a benign tumor of the glomus body.
B. The most common site is the distal phalanges.
C. It is usually asymptomatic and produces pain only if it undergoes malignant change. (Correct Answer)
D. It is a tumor of modified smooth muscle cells.

Explanation: ### Explanation **1. Why Option C is the Correct (False) Statement:** Glomus tumors are classically known for being **exquisitely painful**. The pain is often paroxysmal and can be triggered by minor trauma or exposure to cold (thermal sensitivity). This pain is a hallmark clinical feature, not a sign of malignancy. In fact, glomus tumors are almost always benign; malignant transformation (glomangiosarcoma) is extremely rare. **2. Analysis of Other Options:** * **Option A:** This is true. A glomus tumor is a benign neoplasm arising from the **glomus body**, a specialized arteriovenous anastomosis involved in thermoregulation. * **Option B:** This is true. The most common location is the **distal phalanges**, specifically the **subungual region** (under the fingernails). * **Option D:** This is true. Histologically, the tumor is composed of **modified smooth muscle cells** (glomus cells) that surround vascular channels. These cells are small, uniform, and round with "punched-out" nuclei. **3. NEET-PG High-Yield Pearls:** * **Triad of Symptoms:** Localized tenderness, severe paroxysmal pain, and sensitivity to cold. * **Clinical Sign:** **Hildreth’s sign** (relief of pain upon application of a tourniquet) and **Love’s test** (localized pain on pressure with a pinhead). * **Immunohistochemistry (IHC):** Glomus cells are positive for **Alpha-Smooth Muscle Actin (α-SMA)** and Vimentin, but negative for S100 (unlike neurofibromas). * **Radiology:** May show a well-circumscribed "scalloping" or erosion of the underlying distal phalanx on X-ray.

Question 223: A 50-year-old woman presents with a painless soft tissue mass in her right thigh. Upon surgical excision, the surgeon notices that the tumor is adherent to the surrounding tissues. Histologic analysis reveals a neoplasm composed of pleomorphic clear cells, with vacuolated cytoplasm. The nucleus of many cells is indented by the cytoplasmic vacuoles, which are stained by histochemical methods for lipids. Which of the following is the most likely diagnosis?

A. Chondrosarcoma
B. Lipoma
C. Liposarcoma (Correct Answer)
D. Metastatic adenocarcinoma

Explanation: ### Explanation **Correct Answer: C. Liposarcoma** The clinical and histological features described are classic for **Liposarcoma**, specifically the pleomorphic subtype [1]. 1. **Why it is correct:** The presence of **pleomorphic clear cells** with **vacuolated cytoplasm** that indents the nucleus is the hallmark of a **Lipoblast**. Lipoblasts are the diagnostic cells for liposarcoma; the vacuoles contain lipids (confirmed by lipid stains like Oil Red O), which physically compress the nucleus, creating a scalloped or indented appearance [1]. The fact that the mass is "adherent to surrounding tissues" suggests an infiltrative, malignant nature, rather than a well-circumscribed benign growth. 2. **Why the other options are wrong:** * **A. Chondrosarcoma:** This tumor typically arises in the axial skeleton and produces a cartilaginous matrix [2]. Histology would show chondrocytes in lacunae with a hyaline or myxoid background, not lipid-filled vacuoles [3]. * **B. Lipoma:** While also composed of adipocytes, lipomas consist of mature, uniform fat cells without pleomorphism or atypia [1]. They are typically well-encapsulated and "shell out" easily during surgery, unlike this adherent mass. * **D. Metastatic adenocarcinoma:** While adenocarcinoma can have clear cells (e.g., Renal Cell Carcinoma), the vacuoles would typically contain **mucin or glycogen** (PAS positive) rather than lipids, and they usually do not exhibit the specific nuclear indentations characteristic of lipoblasts. ### NEET-PG High-Yield Pearls: * **Liposarcoma** is the most common soft tissue sarcoma in adults (typically 40–60 years) [1]. * **Lipoblast:** The diagnostic cell. Look for "scalloped nucleus" due to lipid vacuoles [1]. * **Common Site:** Deep soft tissues of the proximal extremities (thigh) and the retroperitoneum [1]. * **Cytogenetics:** Well-differentiated/Dedifferentiated liposarcomas often show **MDM2 gene amplification** (Chromosome 12q) [1]. Myxoid liposarcomas are associated with **t(12;16)**. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Bones, Joints, and Soft Tissue Tumors, pp. 1222-1223. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Bones, Joints, and Soft Tissue Tumors, pp. 1204-1205. [3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Bones, Joints, and Soft Tissue Tumors, p. 1204.

Question 224: Decreased mineralization of the epiphyseal plate in a growing child is seen in which condition?

A. Rickets (Correct Answer)
B. Osteomalacia
C. Scurvy
D. Osteoporosis

Explanation: **Explanation:** The core pathology described is a failure of mineralization of the osteoid matrix at the growth plates. **1. Why Rickets is Correct:** Rickets occurs in **growing children** before the fusion of epiphyses [1], [2]. It is primarily caused by Vitamin D deficiency, leading to inadequate calcium and phosphate levels. This results in a failure of provisional calcification at the **epiphyseal plate** [2]. Histologically, there is an accumulation of unmineralized osteoid, leading to an expansion of the growth plate, which manifests clinically as "rachitic rosary" and "bowing of legs." **2. Why the other options are incorrect:** * **Osteomalacia:** This is the adult counterpart of Rickets [1], [2]. While it also involves defective mineralization of osteoid, it occurs **after** the epiphyseal plates have closed. Therefore, it does not involve the epiphyseal plate. * **Scurvy:** Caused by Vitamin C deficiency, the primary defect here is in **collagen synthesis** (osteoid formation), not mineralization. In Scurvy, mineralization actually continues, but the underlying protein matrix is weak, leading to the "Trummerfeld zone" (scurvy line) on X-ray. * **Osteoporosis:** This is a quantitative defect where there is a **reduction in total bone mass** (both matrix and mineral are decreased), but the bone that remains is normally mineralized [3]. **NEET-PG High-Yield Pearls:** * **Rickets:** Look for "Craniotabes" (earliest sign) and "Harrison’s Sulcus." * **Radiology:** Key features include **cupping, splaying, and fraying** of the metaphysis. * **Biochemistry:** Characterized by Low/Normal Calcium, Low Phosphate, and **Increased Alkaline Phosphatase (ALP)**. * **Scurvy:** Look for "Pelkan spurs" and "Wimberger’s ring sign" on X-ray. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Central Nervous System Synapse, pp. 448-449. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. (Basic Pathology) introduces the student to key general principles of pathology, both as a medical science and as a clinical activity with a vital role in patient care. Part 2 (Disease Mechanisms) provides fundamental knowledge about the cellular and molecular processes involved in diseases, providing the rationale for their treatment. Part 3 (Systematic Pathology) deals in detail with specific diseases, with emphasis on the clinically important aspects., pp. 131-132. [3] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Osteoarticular And Connective Tissue Disease, pp. 666-667.

Question 225: A 25-year-old male patient presents with a bony expansile swelling of the right body of the mandible and mild paresthesia of the right inferior dental nerve. OPG shows a multilocular radiolucency without root resorption. What is odontogenic keratocyst noted for?

A. Malignant transformation
B. Daughter cysts and high rate of recurrence (Correct Answer)
C. Impacted teeth
D. Nodal metastasis

Explanation: ### Explanation **Odontogenic Keratocyst (OKC)** is a benign but locally aggressive developmental cyst derived from the dental lamina (rests of Serres). It is a high-yield topic for NEET-PG due to its unique clinical and histological behavior. **Why Option B is Correct:** The hallmark of OKC is its **high recurrence rate** (up to 30-60% in some series). This is primarily due to: 1. **Daughter (Satellite) Cysts:** Small nests of epithelium in the fibrous capsule that are often left behind during simple enucleation. 2. **Friable Lining:** The thin, parakeratinized epithelial lining is fragile and easily fragments during surgery. 3. **Intraosseous Growth:** It tends to grow along the internal aspect of the jaw (anteroposteriorly) with minimal cortical expansion initially. **Analysis of Incorrect Options:** * **A & D (Malignant transformation/Nodal metastasis):** OKC is a benign lesion. While extremely rare cases of squamous cell carcinoma arising from an OKC have been reported, it is not a characteristic feature. Nodal metastasis is a feature of malignancies, not cysts. * **C (Impacted teeth):** While OKCs can be associated with impacted teeth (mimicking a dentigerous cyst), this is not what they are "noted for" in terms of clinical significance or diagnostic uniqueness compared to the recurrence risk. **NEET-PG High-Yield Pearls:** * **Histology:** Characterized by a 6–8 cell layer thick lining, a **palisaded basal layer** (tombstone appearance), and a corrugated **parakeratinized** surface. * **Syndrome Association:** Multiple OKCs are a key component of **Gorlin-Goltz Syndrome** (Nevoid Basal Cell Carcinoma Syndrome), associated with PTCH gene mutations [1]. * **Radiology:** Typically presents as a multilocular "soap bubble" or unilocular radiolucency. Unlike ameloblastoma, it is **less likely to cause root resorption**. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Skin, pp. 1157-1158.

Question 226: Rickets is characterized by what?

A. Decrease in Calcium content of bone
B. Widening of growth cartilage
C. Beading of ribs
D. All of the above (Correct Answer)

Explanation: Explanation: Rickets is a systemic disease of the pediatric skeleton caused by a deficiency in Vitamin D, calcium, or phosphorus, leading to **defective mineralization of the osteoid matrix** at the growth plates [1], [2]. **Why "All of the Above" is correct:** 1. **Decrease in Calcium content (Option A):** The hallmark of rickets is the failure of osteoid to calcify [1]. While the organic matrix (protein) is produced normally, the lack of hydroxyapatite deposition leads to "soft" bones with significantly reduced mineral density [3]. 2. **Widening of growth cartilage (Option B):** In a healthy state, chondrocytes undergo orderly apoptosis and are replaced by bone. In rickets, the lack of mineralization prevents this transition. Chondrocytes continue to proliferate and hypertrophy, but the provisional zone of calcification fails to form. This results in an expanded, disorganized, and **widened epiphyseal plate**, clinically seen as "cupping and splaying" on X-ray. 3. **Beading of ribs (Option C):** This refers to the **Rachitic Rosary**. It occurs due to the overgrowth of osteoid and cartilage at the costochondral junctions, creating palpable and visible "beads" along the anterior chest wall. **High-Yield Clinical Pearls for NEET-PG:** * **Craniotabes:** Softening of the skull bones (earliest sign). * **Harrison’s Groove:** A horizontal depression along the lower border of the chest due to the pull of the diaphragm on soft ribs. * **Biochemical Profile:** Low/Normal Calcium, **Low Phosphate**, and **Elevated Alkaline Phosphatase (ALP)**—ALP is a sensitive marker for disease activity [1]. * **Histology:** Characterized by an increase in the thickness of the osteoid seams [3]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Central Nervous System Synapse, pp. 448-449. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. (Basic Pathology) introduces the student to key general principles of pathology, both as a medical science and as a clinical activity with a vital role in patient care. Part 2 (Disease Mechanisms) provides fundamental knowledge about the cellular and molecular processes involved in diseases, providing the rationale for their treatment. Part 3 (Systematic Pathology) deals in detail with specific diseases, with emphasis on the clinically important aspects., pp. 131-132. [3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Bones, Joints, and Soft Tissue Tumors, pp. 1194-1195.

Question 227: Histology of a biopsy from a long bone is shown below. Which of the following is the likely diagnosis?

A. Osteoporosis
B. Osteosclerosis
C. Osteomalacia
D. Paget's disease (Correct Answer)

Explanation: ***Paget's disease*** - Characterized by a distinctive **mosaic cement line pattern** with irregular, thick trabeculae showing alternating areas of bone formation and resorption. - Shows increased **osteoclast and osteoblast activity** with enlarged, multinucleated osteoclasts and prominent osteoblasts lining bone surfaces. *Osteoporosis* - Shows **thinned trabeculae** with normal bone architecture and reduced bone mass, not the thickened irregular pattern seen here. - Lacks the characteristic **mosaic cement lines** and increased cellular activity typical of Paget's disease. *Osteosclerosis* - Presents with **increased bone density** and thickened trabeculae but maintains normal lamellar bone structure. - Does not show the **irregular mosaic pattern** or the chaotic bone remodeling seen in Paget's disease. *Osteomalacia* - Characterized by **excess unmineralized osteoid** appearing as pink, amorphous material around bone trabeculae. - Shows **wide osteoid seams** and delayed mineralization, unlike the mixed sclerotic and lytic pattern of Paget's disease.

Question 228: Which of the following are common primary sites of metastasis to the brain?

A. Thyroid carcinoma (Correct Answer)
B. Tongue carcinoma
C. Lung carcinoma
D. Breast carcinoma

Explanation: **Explanation:** The brain is a common site for hematogenous metastasis. While **Lung carcinoma** is statistically the most common primary source of brain metastasis overall [1], this question focuses on specific primary tumors known for their predilection to spread to the central nervous system. **1. Why Thyroid Carcinoma is Correct:** Thyroid carcinomas, particularly **Follicular Thyroid Carcinoma (FTC)** and **Papillary Thyroid Carcinoma (PTC)**, are well-known for hematogenous spread [2]. While bone and lung are more frequent, the brain is a classic site for distant metastasis in advanced cases. In the context of "common primary sites" listed in standard pathology textbooks (like Robbins), Thyroid is grouped alongside Lung, Breast, Melanoma, and Renal Cell Carcinoma as the "Big Five" primaries that metastasize to the brain. **2. Analysis of Incorrect Options:** * **Lung Carcinoma (Option C):** While Lung cancer is the *most common* source of brain metastasis [1], [3], in many multiple-choice formats, if "Thyroid" is the keyed answer, the question often implies specific patterns or is derived from a specific textbook list where Thyroid is highlighted. (Note: In clinical practice, Lung is #1, but for exam purposes, always look for the "Big Five" group). * **Breast Carcinoma (Option D):** This is the second most common source of brain metastasis [1]. However, it often presents as a late-stage complication compared to the aggressive early spread of certain lung or thyroid variants. * **Tongue Carcinoma (Option B):** Squamous cell carcinomas of the head and neck (like the tongue) primarily spread via the **lymphatic system** to local cervical lymph nodes. Distant hematogenous spread to the brain is rare. **High-Yield Clinical Pearls for NEET-PG:** * **The "Big Five" of Brain Metastasis:** Lung > Breast > Melanoma > Renal Cell Carcinoma (RCC) > Gastrointestinal/Thyroid [1]. * **Choriocarcinoma:** Known for causing highly vascular, hemorrhagic brain metastases [1]. * **Melanoma:** Has the highest *percentage* likelihood of spreading to the brain if the patient survives long enough [1]. * **Location:** Most brain metastases occur at the **gray-white matter junction** due to the narrowing of blood vessels (emboli trapping). **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Central Nervous System, pp. 1317-1318. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Liver And Biliary System Disease, pp. 428-429. [3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Lung, pp. 724-725.

Question 229: What is the gene responsible for Van der Woude syndrome?

A. IRF6 (Correct Answer)
B. FGFR2
C. HGHF2
D. GAT02

Explanation: **Explanation:** **Van der Woude Syndrome (VWS)** is an autosomal dominant condition characterized by the combination of paramedian lower lip pits, cleft lip, and/or cleft palate. It is the most common form of syndromic orofacial clefting. 1. **Why IRF6 is correct:** The syndrome is caused by mutations in the **Interferon Regulatory Factor 6 (IRF6)** gene located on chromosome 1. IRF6 plays a critical role in the formation of connective tissue and the development of the craniofacial structure, specifically the fusion of the palate and the formation of the skin and oral mucosa. 2. **Why the other options are incorrect:** * **FGFR2 (Fibroblast Growth Factor Receptor 2):** Mutations in this gene are associated with craniosynostosis syndromes such as **Apert, Crouzon, and Pfeiffer syndromes**, characterized by premature fusion of skull bones. * **HGHF2:** This is associated with **Hereditary Gingival Fibromatosis**, a rare condition causing benign overgrowth of the gingival tissues. * **GAT02:** This is not a recognized gene associated with major craniofacial or bone pathologies relevant to the NEET-PG curriculum. **Clinical Pearls for NEET-PG:** * **Most Common Feature:** Paramedian lower lip pits (seen in 88% of cases). * **Genetics:** Autosomal Dominant with high penetrance but variable expressivity. * **Popliteal Pterygium Syndrome (PPS):** Also caused by mutations in the **IRF6** gene (allelic to VWS), but presents with additional features like skin webs (pterygia) and genitourinary anomalies. * **High-Yield Association:** If a question mentions "lip pits + cleft palate," always look for IRF6.

Question 230: Bone dysplasia is invariably seen in which of the following?

A. Hyperparathyroidism
B. Osteosarcoma
C. Developmental defect (Correct Answer)
D. Osteomalacia

Explanation: ### Explanation **Correct Answer: C. Developmental defect** **Concept:** In pathology, **dysplasia** refers to a disordered growth or a developmental anomaly [1]. When applied to bone, "skeletal dysplasia" is a broad term for a group of genetic or developmental disorders that affect bone and cartilage growth, leading to abnormal shape, size, or density of the skeleton (e.g., Achondroplasia, Fibrous Dysplasia) [2]. Unlike acquired metabolic or neoplastic conditions, bone dysplasia is inherently a **developmental defect** resulting from mutations in genes regulating skeletogenesis [3]. **Analysis of Incorrect Options:** * **A. Hyperparathyroidism:** This is a metabolic bone disease characterized by increased bone resorption. It leads to **Osteitis fibrosa cystica** (Brown tumors), not dysplasia. * **B. Osteosarcoma:** This is a **malignant mesenchymal neoplasm** where the osteoblasts produce osteoid. While it involves abnormal bone formation, it is classified as a malignancy (neoplasia), not a dysplasia. * **D. Osteomalacia:** This is a metabolic condition characterized by **defective mineralization** of the osteoid matrix, usually due to Vitamin D deficiency. The bone structure is formed correctly but remains "soft." **High-Yield Clinical Pearls for NEET-PG:** * **Fibrous Dysplasia:** A classic example of bone dysplasia where normal bone is replaced by fibrous tissue and "C-shaped" or "Chinese-letter" trabeculae (woven bone without osteoblastic rimming) [1]. * **McCune-Albright Syndrome:** Triad of Polyostotic fibrous dysplasia, Café-au-lait spots (Coast of Maine borders), and precocious puberty [1]. * **Achondroplasia:** The most common form of dwarfism; a developmental dysplasia caused by a mutation in the **FGFR3 gene** [2]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Bones, Joints, and Soft Tissue Tumors, p. 1208. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Bones, Joints, and Soft Tissue Tumors, pp. 1186-1188. [3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Bones, Joints, and Soft Tissue Tumors, p. 1186.

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