Bone and Soft Tissue Pathology Practice Questions

Q: Hyperparathyroidism causes which of the following conditions?

Osteitis fibrosa cystica. **Explanation:** **Osteitis fibrosa cystica** is the classic skeletal manifestation of advanced hyperparathyroidism (HPT) [1]. In HPT, excess Parathyroid Hormone (PTH) stimulates massive osteoclastic activity. This leads to the replacement of normal marrow with fibrovascular tissue and the formation of cystic lesions [2]. A hallmark feature is the **"Brown Tumor,"** which is not a true neoplasm but a collection of giant cells, hemorrhage, and hemosiderin pigment within these cystic spaces [1]. Radiologically, this presents as "salt and pepper" skull and subperiosteal bone resorption (most common in the phalanges) [2]. **Analysis of Incorrect Options:** * **A. Osteitis deformans:** Also known as **Paget’s disease of bone**, this is a disorder of bone remodeling characterized by disorganized bone formation (mosaic pattern) and is not caused by PTH imbalance. * **B. Osteogenesis imperfecta:** A genetic "brittle bone" disease caused by mutations in **Type I collagen** synthesis, leading to frequent fractures and blue sclera. * **C. Ameloblastoma:** A benign but locally aggressive odontogenic tumor of the jaw, unrelated to systemic endocrine disorders like hyperparathyroidism. **NEET-PG High-Yield Pearls:** * **Von Recklinghausen’s disease of bone** is the eponym for Osteitis fibrosa cystica (not to be confused with Neurofibromatosis Type 1) [1]. * **Biochemical Profile:** High PTH, High Serum Calcium, and Low Serum Phosphate (in primary HPT). * **Radiology:** Look for "Rugger-Jersey spine" in secondary HPT (renal osteodystrophy). * **Histology:** "Dissecting osteitis" where osteoclasts tunnel into the center of bony trabeculae [2]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Endocrine System, pp. 1105-1106. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Bones, Joints, and Soft Tissue Tumors, p. 1194.

Q: What is the most common lesion that simulates a cementoblastoma?

Periapical cemento-osseous dysplasia. **Explanation:** The **Cementoblastoma** is a true neoplasm of cementoblasts, characterized radiographically by a well-defined radiopaque mass attached to the root of a tooth, typically surrounded by a thin radiolucent halo. **Why Periapical Cemento-osseous Dysplasia (PCOD) is the correct answer:** PCOD is the most common lesion that mimics cementoblastoma because, in its **mature (late) stage**, it presents as a dense radiopaque mass located at the apex of a tooth. While PCOD is a reactive/dysplastic process rather than a neoplasm, its radiographic appearance—a dense opacity often surrounded by a radiolucent rim—closely resembles cementoblastoma. The key clinical differentiator is that in PCOD, the tooth remains **vital**, and the lesion is not physically fused to the root, unlike cementoblastoma. **Analysis of Incorrect Options:** * **Periapical Sclerosing Osteitis (Condensing Osteitis):** This is a reaction to low-grade chronic inflammation (pulpitis). While radiopaque, it lacks the characteristic radiolucent rim seen in cementoblastoma and PCOD. * **Dense Bone Island (Idiopathic Osteosclerosis):** This is a localized growth of compact bone. It is not associated with an inflammatory trigger and typically lacks a radiolucent capsule. * **Hypercementosis:** This is the non-neoplastic deposition of excessive cementum. While it involves the root, it usually results in a smooth, club-shaped enlargement of the root rather than a distinct, large globular mass. **NEET-PG High-Yield Pearls:** * **Cementoblastoma:** Always attached to the root; causes root resorption; usually involves the **mandibular first molar**. * **PCOD:** Most common in **middle-aged African/Asian females**; typically involves **mandibular anterior teeth**; teeth are always **vital**. * **Key Radiographic Sign:** The "radiolucent rim" is a hallmark for both Cementoblastoma and mature PCOD.

Q: Peutz-Jeghers Syndrome is characterized by which mode of inheritance?

Autosomal dominant inheritance. **Explanation:** **Peutz-Jeghers Syndrome (PJS)** is a rare, hereditary polyposis syndrome characterized by the development of multiple hamartomatous polyps in the gastrointestinal tract and mucocutaneous hyperpigmentation. 1. **Why Autosomal Dominant is Correct:** PJS follows an **Autosomal Dominant (AD)** inheritance pattern. It is primarily caused by a germline mutation in the **STK11 (also known as LKB1)** gene located on chromosome 19p13.3 [1]. This gene acts as a tumor suppressor that regulates cell polarity and energy metabolism [1]. Because it is AD, a child of an affected parent has a 50% chance of inheriting the mutation. 2. **Why Other Options are Incorrect:** * **Autosomal Recessive:** While some polyposis syndromes like *MUTYH-associated polyposis (MAP)* are recessive, PJS consistently shows vertical transmission across generations, typical of AD disorders. * **X-linked (Dominant/Recessive):** The STK11 gene is located on an autosome (Chromosome 19), not a sex chromosome. Therefore, the disease affects males and females equally and can be passed from father to son, which rules out X-linked inheritance. **Clinical Pearls for NEET-PG:** * **Triad:** Hamartomatous polyps (most common in the small intestine), mucocutaneous melanin pigmentation (lips, buccal mucosa, hands), and increased cancer risk. * **Histology:** The hallmark is the **"arborizing" pattern** of smooth muscle fibers extending into the polyp fronds. * **Cancer Risk:** Patients have a significantly high risk of GI cancers (colorectal, pancreatic) and extra-GI cancers (breast, ovary, cervix, and **Sertoli cell tumors** of the testes) [1]. * **Intussusception:** The large hamartomatous polyps often act as lead points, making intussusception a common surgical complication. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Gastrointestinal Tract, pp. 813-814.

Q: A static bone cyst is a cyst developing from which tissue?

None of the above. A **Static Bone Cyst**, also known as a **Stafne Bone Cyst** or Stafne defect, is not a true cyst because it lacks an epithelial lining. Instead, it is a developmental depression or concavity found on the lingual aspect of the mandible. ### **Explanation of the Correct Answer** The correct answer is **None of the above** because a static bone cyst does not develop from odontogenic, mucosal, or infectious tissues. It is an **anatomical variation** where the cortical bone of the mandible is indented by **ectopic salivary gland tissue** (usually the submandibular gland). Since it is a bone indentation containing normal glandular tissue rather than a fluid-filled pathologic cavity, it is considered a "pseudocyst." ### **Analysis of Incorrect Options** * **Option A:** While it involves the salivary gland, it is **not an infection**. It is a developmental anomaly where the gland is simply displaced into a bony depression. * **Option B:** It has no relation to the **odontogenic apparatus** (the tissues that form teeth). Unlike Radicular or Dentigerous cysts, it does not arise from the dental lamina or enamel organ. * **Option C:** It does not arise from the **oral mucosa**. It is located deep on the lingual cortical plate, typically below the inferior alveolar canal. ### **High-Yield NEET-PG Pearls** * **Location:** Classically located in the **posterior mandible**, below the mylohyoid line and the mandibular canal. * **Radiographic Appearance:** Appears as a well-demarcated, ovoid, unilocular radiolucency. * **Clinical Feature:** It is **asymptomatic** and usually discovered incidentally on routine panoramic X-rays. * **Management:** No treatment is required; it remains "static" (unchanged) over time. Biopsy is unnecessary if the radiographic location is classic.

Question 1

Hyperparathyroidism causes which of the following conditions?

Accepted Answer

Osteitis fibrosa cystica

Answer

Osteitis deformans

Answer

Osteogenesis imperfecta

Answer

Ameloblastoma

Question 2

What is the most common lesion that simulates a cementoblastoma?

Accepted Answer

Periapical cemento-osseous dysplasia

Answer

Periapical sclerosing osteitis

Answer

Dense bone island

Answer

Hypercementosis

Question 3

A 69-year-old woman presents with a hip fracture sustained from a fall. She has a history of recurrent pneumonia over the past year. Laboratory findings include a normal white blood cell count, thrombocytopenia, and an elevated erythrocyte sedimentation rate (ESR). X-rays show multiple lytic bone lesions. Serum electrophoresis reveals an M-protein spike. What is the most likely diagnosis?

Accepted Answer

Multiple myeloma (plasma cell myeloma)

Answer

Chronic lymphocytic leukemia

Answer

Monoclonal gammopathy of uncertain significance

Answer

Plasmacytoma

Question 4

Osteosclerotic bone metastasis is found most commonly in which carcinoma?

Accepted Answer

Prostate

Answer

Kidney

Answer

Thyroid

Answer

Lung

Question 5

A 39-year-old woman is evaluated for severe left hip pain after twisting her leg. She has bony deformities of the lower extremities with limited mobility. The patient had a history of precocious puberty and hyperthyroidism, which was managed by radioiodine therapy. Physical examination shows large, hyperpigmented macules with irregular borders located on the left shoulder, left side of the neck, and left buttock. Which of the following genes is involved in this condition?

Accepted Answer

GNAS

Answer

PTEN

Answer

RET

Answer

STK11

Question 6

Peutz-Jeghers Syndrome is characterized by which mode of inheritance?

Accepted Answer

Autosomal dominant inheritance

Answer

Autosomal recessive inheritance

Answer

X-linked recessive inheritance

Answer

X-linked dominant inheritance

Question 7

In Osteogenic sarcoma, what is the predominant histological finding?

Accepted Answer

Osteoid forming tumor cells

Answer

Giant cell

Answer

Fibroblastic proliferation

Answer

Chondroblasts

Question 8

In bone infarcts, all are true except?

Accepted Answer

Bone infarcts occur in thalassaemia major.

Answer

Dysbaric osteonecrosis is commonly juxta-articular.

Answer

Bone infarcts occur in Gaucher's disease.

Answer

Bone infarcts are often diaphyseal in sickle cell disease.

Question 9

A static bone cyst is a cyst developing from which tissue?

Accepted Answer

None of the above

Answer

Infection of salivary gland in the mandible

Answer

Tissue of the odontogenic apparatus

Answer

Tissue of the oral mucosa

Question 10

A 10-year-old child presents with a predisposition to fractures, anemia, hepatosplenomegaly, and diffusely increased radiographic density of bones. What is the most likely diagnosis?

Accepted Answer

Osteopetrosis

Answer

Osteogenesis imperfecta

Answer

Pyknodysostosis

Answer

Myelofibrosis

Bone and Soft Tissue Pathology — MCQs

Bone and Soft Tissue Pathology — MCQs

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