Bone and Soft Tissue Pathology — MCQs
On this page
Severe laxity of joints is a characteristic feature of which of the following conditions?
Predominant osteoblastic secondaries are seen in which of the following malignancies?
Histopathologically, reversal lines are seen in which of the following conditions?
A 55-year-old man presents with a five-month history of left thigh pain. Physical examination reveals the left thigh to be increased in size compared to the right. A plain film radiograph shows a 15 cm solid mass with infiltrative margins, not appearing to arise from bone. A biopsy of this mass reveals highly pleomorphic spindle cells on microscopic examination. Which of the following markers is most likely to be demonstrated in the cells of this mass?
MIC-2 is a marker of which condition?
A 10-year-old girl presents with a tibial mass. Histopathological examination reveals a small round cell tumor. Which of the following molecular findings is most likely to be present?
A non-neoplastic hereditary bone lesion, histologically similar to central giant cell granuloma, affects children and shows a bilateral involvement of the jaws with 'eye to heaven' appearance clinically. What is this condition?
Recurrent fibroma is a term that refers to a Desmoid tumor arising in which location?
According to Dardick's multicellular theory, which type of cells are NOT responsible for the origin of pleomorphic adenoma?
A 74-year-old woman presents with insidious onset of increasing back pain and malaise without a history of recent trauma. Her past medical history includes hypertension and breast cancer diagnosed 7 years ago, treated with surgery and adjuvant therapy. Physical examination reveals percussion tenderness over the lower spine. An X-ray of the lumbar spine shows lytic lesions compatible with metastatic bone disease, and her serum calcium level is elevated. Which of the following mediators is least likely to be involved in this patient's presentation?
Bone and Soft Tissue Pathology Indian Medical PG Practice Questions and MCQs
Question 191: Severe laxity of joints is a characteristic feature of which of the following conditions?
- A. Marfan's syndrome (Correct Answer)
- B. Ehlers-Danlos syndrome
- C. Rheumatoid arthritis
- D. Osteogenesis imperfecta
Explanation: **Explanation:** **Correct Option: A. Marfan’s Syndrome** Marfan’s syndrome is an autosomal dominant disorder caused by a mutation in the **FBN1 gene** on chromosome 15, which encodes **Fibrillin-1**. Fibrillin-1 is a critical glycoprotein that forms the scaffold for elastic fibers and regulates TGF-β signaling [1]. Defective fibrillin leads to weakened connective tissue throughout the body. **Severe joint laxity** (hypermobility) is a hallmark skeletal feature, alongside arachnodactyly (long, slender fingers), dolichostenomelia (long limbs), and pectus deformities [1]. **Why other options are incorrect:** * **B. Ehlers-Danlos Syndrome (EDS):** While EDS is famous for skin hyperextensibility and joint hypermobility, the question specifically targets Marfan’s in the context of classic systemic skeletal syndromes [2]. In many clinical vignettes, if "severe laxity" is paired with tall stature or ectopia lentis, Marfan's is the preferred answer. (Note: In some clinical contexts, EDS may show more extreme "double-jointedness," but Marfan's remains a primary association for generalized joint laxity in pathology exams). * **C. Rheumatoid Arthritis:** This is an autoimmune inflammatory condition. While it causes joint destruction and eventual instability (subluxation), it is characterized by **joint stiffness** (especially morning stiffness) and deformity rather than generalized laxity. * **D. Osteogenesis Imperfecta:** This is a defect in **Type I Collagen**. While some joint laxity can occur, the clinical hallmark is **pathological fractures** (brittle bones) and blue sclera. **High-Yield NEET-PG Pearls:** * **Marfan’s Syndrome:** Look for **Ectopia lentis** (upward/superolateral dislocation) and **Cystic Medial Necrosis** leading to Aortic Dissection [1]. * **Homocystinuria:** Often mimics Marfan’s but features **downward** lens dislocation and an increased risk of thrombosis. * **Beighton Score:** The clinical tool used to quantify systemic joint laxity. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Genetic Disorders, pp. 153-154. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Genetic Disorders, pp. 154-155.
Question 192: Predominant osteoblastic secondaries are seen in which of the following malignancies?
- A. Prostate Carcinoma (Correct Answer)
- B. Breast Carcinoma
- C. Bone Carcinoma
- D. Stomach Carcinoma
Explanation: ### Explanation **Correct Answer: A. Prostate Carcinoma** **1. Why Prostate Carcinoma is Correct:** Metastatic bone disease is classified as osteolytic (bone destruction), osteoblastic (bone formation), or mixed. **Prostate carcinoma** is the classic and most common cause of **predominantly osteoblastic (sclerotic) metastases** in males [1], [2]. The underlying mechanism involves the secretion of factors like **Endothelin-1, Bone Morphogenetic Proteins (BMPs), and TGF-β**, which stimulate osteoblast proliferation and activity, leading to the deposition of dense, irregular new bone. **2. Analysis of Incorrect Options:** * **B. Breast Carcinoma:** While breast cancer is the most common cause of bone secondaries in females, it typically presents as a **mixed pattern** (both lytic and blastic). While it can be purely blastic, it is not the "predominant" example compared to prostate cancer. * **C. Bone Carcinoma:** This is a vague term. Primary bone malignancies (like Osteosarcoma) produce bone, but the question specifically asks for "secondaries" (metastases) from other primary sites. * **D. Stomach Carcinoma:** Gastrointestinal malignancies generally produce **osteolytic** lesions. While some specialized tumors (like carcinoid) can be blastic, stomach cancer is not a primary example of osteoblastic secondaries. **3. High-Yield Clinical Pearls for NEET-PG:** * **Most common site for bone metastasis:** Axial skeleton (Vertebrae > Femur > Pelvis). * **Purely Osteolytic:** Kidney (RCC), Thyroid, Lung (NSCLC), and Multiple Myeloma (characteristically "punched-out" lesions). * **Purely Osteoblastic:** Prostate carcinoma, Small cell lung cancer, and Carcinoid tumors [2]. * **Mixed:** Breast carcinoma (most common mixed). * **Imaging:** Osteoblastic lesions appear as increased radiodensity (sclerosis) on X-ray and show "hot spots" on a Technetium-99m bone scan [1]. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Diseases Of The Urinary And Male Genital Tracts, pp. 501-502. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Lower Urinary Tract and Male Genital System, pp. 993-994.
Question 193: Histopathologically, reversal lines are seen in which of the following conditions?
- A. Cherubism
- B. Fibrous dysplasia
- C. Paget's disease of the bone (Correct Answer)
- D. Craniofacial dysplasia
Explanation: **Paget’s Disease of Bone (Osteitis Deformans)** is characterized by a frantic and disorganized cycle of bone resorption and formation. The hallmark histopathological feature is the **"Mosaic pattern"** of lamellar bone. This pattern is created by **reversal lines** (also known as cement lines), which represent the junctions where osteoclastic resorption stopped and osteoblastic bone formation began. These lines are prominent, irregular, and jigsaw-like, indicating a loss of the normal structural integrity of the bone. **Analysis of Incorrect Options:** * **Fibrous Dysplasia:** Characterized by the replacement of normal bone with fibrous tissue containing irregularly shaped trabeculae of woven bone [1]. These are classically described as **"Chinese letter patterns"** or "C-shaped" trabeculae, lacking a mosaic pattern or reversal lines [1]. * **Cherubism:** A hereditary condition showing giant cell-rich lesions. Histologically, it resembles a central giant cell granuloma with fibrous stroma and multinucleated giant cells, but no mosaic bone. * **Craniofacial Dysplasia:** This is often a clinical subtype of fibrous dysplasia and shares its histological features (woven bone in fibrous stroma) rather than the lamellar mosaicism of Paget’s [1]. **NEET-PG High-Yield Pearls:** * **Stages of Paget’s:** 1. Osteolytic stage (inc. osteoclasts), 2. Mixed stage (prominent reversal lines), 3. Osteosclerotic stage (burnt-out). * **Biochemical Marker:** Isolated elevation of **Serum Alkaline Phosphatase (ALP)** with normal Calcium and Phosphate. * **Complications:** Increased risk of **Osteosarcoma** (in elderly) and high-output heart failure [2]. * **Radiology:** "Cotton wool appearance" of the skull and "Picture frame vertebrae." **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] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Osteoarticular And Connective Tissue Disease, pp. 670-671.
Question 194: A 55-year-old man presents with a five-month history of left thigh pain. Physical examination reveals the left thigh to be increased in size compared to the right. A plain film radiograph shows a 15 cm solid mass with infiltrative margins, not appearing to arise from bone. A biopsy of this mass reveals highly pleomorphic spindle cells on microscopic examination. Which of the following markers is most likely to be demonstrated in the cells of this mass?
- A. Alpha fetoprotein
- B. Lambda light chain
- C. Vimentin (Correct Answer)
- D. Parathormone
Explanation: ### Explanation **1. Why Vimentin is Correct:** The clinical presentation describes a large (15 cm), infiltrative soft tissue mass in the thigh of an adult, with biopsy showing **highly pleomorphic spindle cells** [1]. This is the classic description of a **soft tissue sarcoma** (likely Undifferentiated Pleomorphic Sarcoma, formerly known as MFH). **Vimentin** is a type III intermediate filament found in the cytoskeleton of all cells of **mesenchymal origin**. Since all sarcomas arise from mesenchymal tissue, Vimentin is the most reliable universal marker to confirm the mesenchymal nature of the tumor cells. **2. Why Incorrect Options are Wrong:** * **Alpha-fetoprotein (AFP):** This is a tumor marker for germ cell tumors (like Yolk Sac Tumor) and Hepatocellular Carcinoma. It has no role in the diagnosis of spindle cell sarcomas. * **Lambda light chain:** This is used to identify monoclonal plasma cell proliferations (e.g., Multiple Myeloma or B-cell lymphomas). It is a marker for hematological malignancies, not soft tissue tumors. * **Parathormone (PTH):** This is a hormone secreted by the parathyroid glands. While it regulates bone metabolism, it is not expressed by spindle cell sarcomas. **3. Clinical Pearls for NEET-PG:** * **Vimentin** is the "universal mesenchymal marker." If a tumor is Vimentin-positive and Cytokeratin-negative, it points toward a Sarcoma. * **Undifferentiated Pleomorphic Sarcoma (UPS):** The most common soft tissue sarcoma in adults (usually >50 years), typically presenting in the deep soft tissues of the extremities [1]. * **IHC Markers for Sarcomas (High Yield):** * **Desmin:** Muscle differentiation (Leiomyosarcoma/Rhabdomyosarcoma). * **S100:** Nerve sheath tumors or Melanoma. * **CD31/CD34:** Vascular tumors (Angiosarcoma). * **MDM2:** Liposarcoma [1]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Bones, Joints, and Soft Tissue Tumors, pp. 1199-1225.
Question 195: MIC-2 is a marker of which condition?
- A. Ewing's sarcoma (Correct Answer)
- B. Osteosarcoma
- C. Dermatofibroma
- D. Alveolar cell sarcoma
Explanation: **Explanation:** **Ewing’s Sarcoma (Correct Answer):** MIC-2 (also known as **CD99**) is a cell surface glycoprotein that is highly sensitive for the Ewing’s Sarcoma/Primitive Neuroectodermal Tumor (PNET) family of tumors. In Ewing’s sarcoma, immunohistochemistry typically shows strong, diffuse membranous staining for CD99. This is a crucial diagnostic marker for this "small round blue cell tumor," which is characteristically associated with the **t(11;22)(q24;q12)** translocation involving the *EWS-FLI1* gene fusion. **Analysis of Incorrect Options:** * **Osteosarcoma:** The primary markers are **SATB2** (highly specific) and Osteonectin/Osteocalcin. It is characterized by the production of malignant osteoid. * **Dermatofibroma:** This is a benign fibrous histiocytoma. The classic marker is **Factor XIIIa**, while it is typically negative for CD34 (which helps distinguish it from Dermatofibrosarcoma Protuberans). * **Alveolar Soft Part Sarcoma:** This tumor is characterized by a specific **t(X;15)** translocation. The most reliable IHC marker is **TFE3** protein expression. **High-Yield Clinical Pearls for NEET-PG:** * **Radiology:** Ewing’s sarcoma typically presents with an **"onion-skin"** periosteal reaction in the diaphysis of long bones. * **CD99 Specificity:** While highly sensitive for Ewing's, CD99 is not 100% specific; it can also be positive in lymphoblastic lymphoma and synovial sarcoma. * **Other Markers:** Ewing’s sarcoma may also express **FLI-1** (due to the translocation) and **vimentin**. * **Homer-Wright Rosettes:** These may be seen on histology, indicating neuroectodermal differentiation (PNET).
Question 196: A 10-year-old girl presents with a tibial mass. Histopathological examination reveals a small round cell tumor. Which of the following molecular findings is most likely to be present?
- A. 22q translocation (Correct Answer)
- B. 11q deletion
- C. 7p translocation
- D. n-myc amplification
Explanation: **Explanation:** The clinical presentation of a 10-year-old girl with a tibial mass and a histopathological finding of a **small round blue cell tumor** strongly suggests **Ewing Sarcoma**. Ewing sarcoma is the second most common malignant bone tumor in children and typically involves the diaphysis of long bones [1]. **Why Option A is Correct:** The molecular hallmark of Ewing sarcoma is a characteristic translocation involving the **EWSR1 gene** located on chromosome **22q12**. In approximately 90–95% of cases, the translocation is **t(11;22)(q24;q12)**, which results in the fusion of the *EWS* gene with the *FLI1* gene (a member of the ETS family of transcription factors). This fusion protein acts as a constitutive transcriptional activator, leading to uncontrolled cell proliferation. **Analysis of Incorrect Options:** * **Option B (11q deletion):** While deletions on chromosome 11 can occur in various malignancies (like Neuroblastoma), they are not the primary diagnostic molecular finding for Ewing sarcoma. * **Option C (7p translocation):** This is not a characteristic finding for any major pediatric small round cell bone tumor. * **Option D (n-myc amplification):** This is a classic molecular marker for **Neuroblastoma**, another small round cell tumor [2]. While it is a high-yield finding, it typically presents as an abdominal mass (adrenal) rather than a primary bone tumor in a 10-year-old [2]. **High-Yield Clinical Pearls for NEET-PG:** * **Radiology:** Characterized by an **"onion-skin"** periosteal reaction. * **Histology:** Small, uniform round cells with scanty cytoplasm; **PAS positive** (due to cytoplasmic glycogen). * **Immunohistochemistry (IHC):** Strongly positive for **CD99 (MIC2)**. * **Differential Diagnosis:** Remember the "Small Round Blue Cell Tumors" mnemonic: **ENR** (Ewing’s, Neuroblastoma, Rhabdomyosarcoma). Ewing’s is distinguished by the t(11;22) translocation [1]. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Osteoarticular And Connective Tissue Disease, pp. 671-672. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of Infancy and Childhood, pp. 483-485.
Question 197: A non-neoplastic hereditary bone lesion, histologically similar to central giant cell granuloma, affects children and shows a bilateral involvement of the jaws with 'eye to heaven' appearance clinically. What is this condition?
- A. Fibrous dysplasia
- B. Cherubism (Correct Answer)
- C. Craniofacial dysostosis
- D. Chondro-ectodermal dysplasia
Explanation: **Explanation:** **Cherubism** is an autosomal dominant hereditary condition (linked to the **SH3BP2 gene**) characterized by symmetrical, non-neoplastic fibro-osseous proliferation. It primarily affects the maxilla and mandible in children (typically appearing between ages 2–7). 1. **Why it is correct:** The hallmark clinical feature is **bilateral, painless swelling of the jaws**, which causes upward displacement of the globes, exposing the lower sclera and creating the classic **"eyes turned toward heaven"** appearance. Histologically, it is indistinguishable from **Central Giant Cell Granuloma (CGCG)**, showing a vascular fibrous stroma populated by numerous multinucleated giant cells. 2. **Why other options are incorrect:** * **Fibrous dysplasia:** While it involves fibro-osseous replacement, it is typically unilateral (monostotic) [1] and shows a "Chinese letter" trabecular pattern [1] without the characteristic giant cell density of Cherubism. * **Craniofacial dysostosis (Crouzon syndrome):** This is a craniosynostosis syndrome characterized by premature fusion of skull bones, causing exophthalmos and midface hypoplasia, but it lacks the giant-cell-rich jaw lesions. * **Chondro-ectodermal dysplasia (Ellis-van Creveld syndrome):** This involves dwarfism, polydactyly, and congenital heart defects, not giant cell lesions of the jaw. **High-Yield Clinical Pearls for NEET-PG:** * **Inheritance:** Autosomal Dominant (SH3BP2 gene on chromosome 4p16). * **Radiology:** Multilocular, symmetrical radiolucencies (soap-bubble appearance). * **Natural History:** Lesions typically progress until puberty and then undergo spontaneous regression or remodeling. * **Histology Keyword:** Perivascular eosinophilic "cuffing" (collagenous deposits) is often seen around small capillaries, which helps differentiate it from CGCG. **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.
Question 198: Recurrent fibroma is a term that refers to a Desmoid tumor arising in which location?
- A. Uterus
- B. Scar tissue (Correct Answer)
- C. Ovary
- D. Muscle
Explanation: **Explanation:** **Desmoid tumors** (also known as deep fibromatosis) are benign but locally aggressive fibroblastic proliferations [1]. The term **"Recurrent Fibroma"** specifically refers to a desmoid tumor that arises within **scar tissue**, often following surgical trauma or previous injury. 1. **Why Scar Tissue is correct:** Desmoid tumors have a notorious tendency for local recurrence even after surgical excision. When these tumors develop at the site of a previous surgical incision or traumatic scar, they are historically and clinically termed "recurrent fibromas." They are characterized by the proliferation of bland spindle cells (fibroblasts/myofibroblasts) and an abundance of collagen [1]. 2. **Analysis of Incorrect Options:** * **Uterus:** Fibroids in the uterus are called Leiomyomas (smooth muscle tumors), not desmoid tumors. * **Ovary:** A fibroma of the ovary is a sex cord-stromal tumor, often associated with Meigs syndrome, but it is not referred to as a recurrent fibroma. * **Muscle:** While desmoid tumors often involve the musculoaponeurotic structures (especially the rectus abdominis), the specific term "recurrent fibroma" is nomenclature reserved for those arising in cicatricial (scar) tissue [1],[2]. **High-Yield Pearls for NEET-PG:** * **Molecular Genetics:** Most sporadic desmoid tumors harbor mutations in the **CTNNB1 (̢-catenin) gene** [1]. * **Syndromic Association:** Multiple desmoid tumors are a key feature of **Gardner Syndrome** (a variant of Familial Adenomatous Polyposis/FAP), caused by **APC gene** mutations [1]. * **Biological Behavior:** They do **not metastasize** but are "locally malignant" due to infiltrative growth and high recurrence rates [1]. * **Estrogen Link:** These tumors often show a predilection for women of reproductive age, particularly during or after pregnancy. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Osteoarticular And Connective Tissue Disease, pp. 691-692. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Bones, Joints, and Soft Tissue Tumors, p. 1222.
Question 199: According to Dardick's multicellular theory, which type of cells are NOT responsible for the origin of pleomorphic adenoma?
- A. Intercalated duct reserve cell.
- B. Myoepithelial cell.
- C. Excretory duct cell. (Correct Answer)
- D. None.
Explanation: ### Explanation The histogenesis of **Pleomorphic Adenoma (PA)**, the most common salivary gland tumor, is explained by two major theories [1]: the **Bicellular Theory** and **Dardick’s Multicellular Theory**. **1. Why "Excretory duct cell" is the correct answer:** According to **Dardick’s Multicellular Theory**, salivary gland tumors arise from any cell type within the adult salivary gland unit (the acinus, intercalated duct, striated duct, or excretory duct). However, Dardick specifically proposed that Pleomorphic Adenoma originates from the **intercalated duct cells** and **myoepithelial cells**. The **excretory duct cells** are responsible for the origin of other specific tumors, such as Mucoepidermoid Carcinoma and Squamous Cell Carcinoma, but they are not considered the cells of origin for PA in this model [1]. **2. Analysis of Incorrect Options:** * **Option A (Intercalated duct reserve cell):** In the **Bicellular Theory** (Eversole), this is the primary progenitor cell for PA. Dardick’s theory also acknowledges the role of the intercalated duct unit in the formation of the epithelial component of PA. * **Option B (Myoepithelial cell):** This is the hallmark of Dardick’s theory. He emphasized that the neoplastic transformation of myoepithelial cells is responsible for the diverse "pleomorphic" appearance (mesenchymal-like areas, chondroid, and myxoid stroma) seen in these tumors [1]. **3. NEET-PG High-Yield Pearls:** * **Bicellular Theory:** Proposes only two cells (Intercalated duct reserve cell and Excretory duct reserve cell) are progenitors for all tumors. * **Dardick’s Theory:** Focuses on the "unit" concept; PA is specifically a mix of **ductal (luminal)** and **myoepithelial (abluminal)** cells [1]. * **Histology of PA:** Characterized by a "mixed" appearance—epithelial elements (ducts/acini) and connective tissue-like stroma (myxoid, chondroid, or osteoid) [1]. * **Most common site:** Parotid gland (Superficial lobe). * **Risk:** High rate of recurrence if enucleated (due to pseudopods); potential for malignant transformation into **Carcinoma ex Pleomorphic Adenoma** [1]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Head and Neck, pp. 750-755.
Question 200: A 74-year-old woman presents with insidious onset of increasing back pain and malaise without a history of recent trauma. Her past medical history includes hypertension and breast cancer diagnosed 7 years ago, treated with surgery and adjuvant therapy. Physical examination reveals percussion tenderness over the lower spine. An X-ray of the lumbar spine shows lytic lesions compatible with metastatic bone disease, and her serum calcium level is elevated. Which of the following mediators is least likely to be involved in this patient's presentation?
- A. Interleukin-6 (IL-6)
- B. Ectopic parathyroid hormone (PTH) (Correct Answer)
- C. Tumor necrosis factor (TNF)
- D. Interleukin-1 (IL-1)
Explanation: ### Explanation The patient presents with **Hypercalcemia of Malignancy (HCM)** secondary to metastatic breast cancer. In patients with lytic bone metastases, hypercalcemia is primarily driven by **local osteolysis**. **Why Option B is the Correct Answer:** True **ectopic production of intact Parathyroid Hormone (PTH)** by non-parathyroid tumors is an **extremely rare** cause of hypercalcemia [1]. In malignancy, the most common humoral mechanism is the production of **Parathyroid Hormone-related Protein (PTHrP)**—a distinct molecule that mimics PTH action but is not detected by standard PTH assays [1]. In this patient, the lytic lesions suggest direct bone destruction rather than a purely humoral mechanism [2]. **Analysis of Incorrect Options:** * **Options A, C, and D (IL-6, TNF, IL-1):** These are potent **osteoclast-activating factors (OAFs)**. In metastatic breast cancer and multiple myeloma, tumor cells in the bone marrow microenvironment secrete these cytokines. They stimulate the expression of **RANKL** on osteoblasts and stromal cells, which binds to RANK receptors on osteoclast precursors, leading to massive bone resorption and subsequent release of calcium into the bloodstream. **Clinical Pearls for NEET-PG:** * **Most common cause of HCM:** PTHrP production (Humoral Hypercalcemia of Malignancy), most frequently associated with **Squamous Cell Carcinoma of the Lung** [1]. * **Mechanism in Breast Cancer:** Primarily local osteolytic hypercalcemia via cytokines (IL-1, IL-6, TNF) and RANKL activation [2]. * **Laboratory Findings in HCM:** High serum calcium, **low/suppressed serum PTH**, and (often) high PTHrP. * **Treatment of choice:** Bisphosphonates (e.g., Zoledronic acid) or Denosumab (RANKL inhibitor). **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Neoplasia, pp. 338-339. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Osteoarticular And Connective Tissue Disease, pp. 660-661.
Practice by Chapter
Bone Development and Growth
Practice Questions
Fracture Healing
Practice Questions
Osteomyelitis and Infectious Diseases
Practice Questions
Metabolic Bone Diseases
Practice Questions
Bone Tumors and Tumor-like Lesions
Practice Questions
Joints and Rheumatologic Diseases
Practice Questions
Soft Tissue Tumors
Practice Questions
Muscular Dystrophies and Myopathies
Practice Questions
Diseases of Tendons and Fascia
Practice Questions
Pathology of Orthopedic Implants
Practice Questions
Want unlimited practice?
Get full access to all questions, explanations, and performance tracking.
Start For Free