Bone and Soft Tissue Pathology Practice Questions

Q: Which of the following conditions is characterized by joint hypermobility and hyperelasticity?

Ehlers-Danlos syndrome. **Explanation:** The correct answer is **Ehlers-Danlos syndrome (EDS)**. EDS is a heterogeneous group of heritable connective tissue disorders characterized by defects in the synthesis or structure of **fibrillar collagen** [1]. Because collagen provides the structural framework for skin, joints, and blood vessels, its deficiency leads to the classic triad of **joint hypermobility**, **skin hyperextensibility**, and **tissue fragility** (easy bruising/scarring) [1]. **Analysis of Options:** * **Marfan Syndrome:** Caused by a mutation in the **FBN1 gene (Fibrillin-1)**. While it presents with joint laxity and long limbs (arachnodactyly), its hallmark features are ectopia lentis (upward lens dislocation) and cardiovascular complications like aortic root aneurysm/dissection. It does not typically feature the extreme skin hyperelasticity seen in EDS. * **Fragile X Syndrome:** A genetic condition causing intellectual disability. While patients may have mild joint laxity and a long face with large ears, it is primarily a neurodevelopmental disorder caused by **CGG trinucleotide repeats** in the FMR1 gene. * **Angelman Syndrome:** A neurogenetic disorder ("Happy Puppet") caused by loss of function of the **UBE3A gene** on chromosome 15. It presents with ataxia, seizures, and frequent laughter, but not connective tissue laxity. **High-Yield NEET-PG Pearls:** * **Classical EDS (Types I/II):** Mutation in **COL5A1/COL5A2** (Type V collagen). Features "cigarette paper" or "papyraceous" scars. * **Vascular EDS (Type IV):** Mutation in **COL3A1** (Type III collagen). Most severe form; prone to spontaneous rupture of the aorta or hollow viscera (e.g., colon). * **Kyphoscoliotic EDS (Type VI):** Due to **Lysyl hydroxylase deficiency**; presents with ocular fragility and severe scoliosis. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Genetic Disorders, pp. 154-156.

Q: The tissue of which lesion has been described as resembling a 'blood soaked sponge with large pores'?

Aneurysmal bone cyst. ### Explanation **Correct Answer: C. Aneurysmal Bone Cyst (ABC)** The description of a **"blood-soaked sponge"** is a classic gross pathological hallmark of an **Aneurysmal Bone Cyst (ABC)**. * **Pathophysiology:** ABC is a benign but locally aggressive osteolytic lesion characterized by blood-filled, cystic spaces separated by connective tissue septa [1]. * **Gross Appearance:** When the lesion is opened, the blood escapes, leaving behind a porous, honeycomb-like architecture that resembles a sponge saturated with blood. * **Microscopy:** The septa contain spindle cells, multinucleated giant cells, and reactive woven bone (osteoid), notably lacking an endothelial lining in the cystic spaces [1]. **Analysis of Incorrect Options:** * **A & B. Cavernous and Capillary Hemangiomas:** While these are vascular tumors, they consist of organized blood vessels lined by endothelium. A cavernous hemangioma contains large, blood-filled vascular channels, but it does not typically present with the "sponge-like" cystic architecture seen in bone pathology. * **D. Eruption Hematoma:** This is a soft tissue cyst (a variant of a dentigerous cyst) associated with an erupting tooth. It appears as a bluish, fluid-filled swelling on the gingiva, not a porous, sponge-like bony lesion. **NEET-PG High-Yield Pearls:** * **Radiology:** ABC typically presents as an **"eccentric, expansile, soap-bubble lesion"** with a "blow-out" appearance [1]. * **MRI Finding:** The presence of **fluid-fluid levels** (due to settling of RBCs) is a highly characteristic diagnostic feature. * **Genetics:** Look for the **USP6 gene rearrangement** on chromosome 17p13 in primary ABCs. * **Common Site:** Metaphysis of long bones and posterior elements of the vertebrae. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Bones, Joints, and Soft Tissue Tumors, pp. 1206-1208.

Q: A 12-year-old girl complains of leg pain persisting for several weeks with a low-grade fever. A radiograph reveals a mass in the diaphyseal region of the left femur with overlying cortical erosion and soft tissue extension. A biopsy of the lesion shows numerous small round cells, rich in PAS-positive diastase-sensitive granules. What is the most likely histological diagnosis?

Ewing's sarcoma. **Explanation:** The clinical presentation and histopathology point definitively to **Ewing’s Sarcoma**. **Why Ewing’s Sarcoma is correct:** 1. **Demographics & Site:** It typically affects children and adolescents (5–15 years) and is the most common bone tumor to involve the **diaphysis** of long bones (femur being the most common site). 2. **Clinical Features:** It often mimics osteomyelitis, presenting with pain, swelling, and systemic signs like **low-grade fever** and elevated ESR. 3. **Histopathology:** It is a "Small Round Blue Cell Tumor." The presence of **PAS-positive, diastase-sensitive granules** is a pathognomonic finding, indicating the presence of **glycogen** in the cytoplasm. **Why other options are incorrect:** * **Osteogenic Sarcoma:** Usually occurs in the **metaphysis** (not diaphysis) and shows malignant osteoid formation on biopsy. It is PAS negative. * **Osteoblastoma:** A benign, bone-forming tumor usually involving the posterior elements of the spine. It does not present with systemic symptoms or small round cells. * **Chondroblastoma:** A benign cartilaginous tumor characteristically located in the **epiphysis** of young patients. Histology shows "chicken-wire" calcification. **NEET-PG High-Yield Pearls:** * **Radiology:** Characterized by "Onion-skin" periosteal reaction and "Codman’s triangle." * **Genetics:** Associated with **t(11;22)** translocation involving the *EWS-FLI1* gene. * **Markers:** Strongly positive for **CD99 (MIC2)**. * **Homer-Wright Rosettes:** May be seen in cases with neuroectodermal differentiation (PNET spectrum).

Q: Compound odontoma shows on a radiograph as what?

Distinguishable tooth-like structures. **Explanation:** Odontomas are the most common odontogenic tumors, classified as hamartomas rather than true neoplasms [1]. They are composed of mature enamel, dentin, cementum, and pulp tissue. **1. Why the correct answer is right:** **Compound Odontomas** are characterized by a high degree of morphodifferentiation. On a radiograph, they appear as a cluster of multiple, small, **distinguishable tooth-like structures** (denticles) contained within a thin radiolucent fibrous capsule. They are most commonly found in the anterior maxilla. **2. Why the incorrect options are wrong:** * **A. Supernumerary teeth:** While they may resemble extra teeth, odontomas are disorganized hamartomatous growths, not fully functional or anatomically independent teeth. * **B. Radiolucent and radiopaque areas:** This is a non-specific description. While odontomas have both components (the calcified mass and the surrounding fibrous capsule), this description applies to many lesions like cementoblastomas or ossifying fibromas. * **C. Masses of calcified areas:** This describes **Complex Odontomas**. Unlike the compound type, complex odontomas show poor morphodifferentiation and appear as a disordered, "sunburst" or amorphous radiopaque mass, typically found in the posterior mandible. **3. High-Yield NEET-PG Pearls:** * **Compound Odontoma:** "Compound = Components" (looks like mini-teeth); Anterior Maxilla. * **Complex Odontoma:** "Complex = Confused" (amorphous mass); Posterior Mandible. * **Clinical Presentation:** Usually asymptomatic; often discovered when they prevent the eruption of a permanent tooth. * **Gardner Syndrome:** Multiple odontomas can be a feature of this syndrome (along with intestinal polyposis and osteomas). **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Head and Neck, pp. 741-742.

Question 1

Which of the following conditions is characterized by joint hypermobility and hyperelasticity?

Accepted Answer

Ehlers-Danlos syndrome

Answer

Marfan syndrome

Answer

Fragile X syndrome

Answer

Angelman syndrome

Question 2

A 45-year-old man presents with back pain and facial pain. Physical examination reveals coarse facial features and kyphosis. Laboratory examination shows elevated alkaline phosphatase. Radiographic studies demonstrate skull thickening with narrowing of foramina, and bowing of the femur and tibia. Bone biopsy reveals a mosaic pattern of bone spicules with prominent osteoid seams. Which of the following neoplasms occurs with increased frequency in patients with this disorder?

Accepted Answer

Osteosarcoma

Answer

Astrocytoma

Answer

Hodgkin's lymphoma

Answer

Meningioma

Question 3

Renal osteodystrophy differs from nutritional osteomalacia by having which of the following?

Accepted Answer

Increased phosphates

Answer

Increased calcium

Answer

Decreased calcium

Answer

None of the above

Question 4

A sample to look for uric acid crystals (gouty tophus) would be submitted to the pathology laboratory in:

Accepted Answer

Alcohol

Answer

Formalin

Answer

Distilled water

Answer

Normal saline

Question 5

The tissue of which lesion has been described as resembling a 'blood soaked sponge with large pores'?

Accepted Answer

Aneurysmal bone cyst

Answer

Cavernous hemangioma

Answer

Capillary hemangioma

Answer

Eruption hematoma

Question 6

A 12-year-old girl complains of leg pain persisting for several weeks with a low-grade fever. A radiograph reveals a mass in the diaphyseal region of the left femur with overlying cortical erosion and soft tissue extension. A biopsy of the lesion shows numerous small round cells, rich in PAS-positive diastase-sensitive granules. What is the most likely histological diagnosis?

Accepted Answer

Ewing's sarcoma

Answer

Osteogenic sarcoma

Answer

Osteoblastoma

Answer

Chondroblastoma

Question 7

A radiologist notes the presence of fine, radiographically dense crystals in the tissues of a knee joint. This patient most likely has which of the following types of arthropathy?

Accepted Answer

Pseudogout

Answer

Gonococcal arthritis

Answer

Gouty arthritis

Answer

Osteoarthritis

Question 8

Compound odontoma shows on a radiograph as what?

Accepted Answer

Distinguishable tooth-like structures

Answer

Supernumerary teeth

Answer

Radiolucent and radiopaque areas

Answer

Masses of calcified areas

Question 9

A 60-year-old male with end-stage kidney disease diagnosed 5 years ago, managed with hemodialysis, hypertension, and diabetes, presents with bone pain and dyspnea. He has poor compliance with medications and hemodialysis. Chest X-ray reveals hazy bilateral infiltrates, and chest CT shows bilateral ground-glass infiltrates. Laboratory studies show elevated calcium and phosphate levels, with a PTH level of 130 pg/ml. What is the best management for this patient?

Accepted Answer

Parathyroidectomy

Answer

Calcitriol 0.5 mg IV with hemodialysis and sevelamer three times daily

Answer

Calcitriol 0.5 mg orally daily with sevelamer 1600 mg three times daily

Answer

More aggressive hemodialysis to achieve optimal fluid and electrolyte balance

Question 10

A patient presents with endocrinopathy, fibrous dysplasia of bone, and hyperpigmentation. What is the possible diagnosis?

Accepted Answer

McCune-Albright syndrome

Answer

Ollier's syndrome

Answer

Mazabraud syndrome

Answer

Maffucci's syndrome

Bone and Soft Tissue Pathology — MCQs

Bone and Soft Tissue Pathology — MCQs

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