Cytopathology — MCQs
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A 27-year-old man develops acute pain and swelling of the left knee 5 days after an episode of urethritis. On physical examination, the left knee is swollen, warm, and tender to the touch. No other joints are affected. Laboratory examination of fluid aspirated from the left knee joint shows numerous neutrophils. A Gram stain of the fluid shows gram-negative intracellular diplococci. No crystals are seen. Which of the following infectious agents is most likely responsible for his condition?
A 60-year-old woman with arthritis suffers a massive stroke and expires. At autopsy, the proximal phalangeal joint tissue shows pannus, synovial cell hyperplasia, and lymphoid follicles. Which of the following best describes the pathogenesis of pannus formation in this patient?
In which color cap vacutainer is NaF used?
A mother delivered an infant at 38 weeks gestation without complications. Soon after delivery, she experienced respiratory distress, uncontrolled vaginal bleeding, shock, and multiorgan failure, leading to death. Autopsy revealed masses of debris and epithelial squamous cells in the pulmonary microcirculation. What was the likely cause of death?
Cervical smear fixation is done by?
Which of the following conditions cannot be diagnosed using fine needle aspiration cytology?
A 17-year-old female underwent a fine needle aspiration cytology (FNAC) for a lump in the breast which was well defined, non-tender and mobile. Which of the following pathological features suggests a diagnosis of a benign lesion?
A 20-year-old female patient presented with a thyroid swelling. Which of the following is least likely to be diagnosed by fine needle aspiration cytology?
A 50-year-old woman with long-standing rheumatoid arthritis complains of weakness and fatigue. She states that her stools have recently become black after taking a new nonsteroidal anti-inflammatory drug (NSAID). Gastroscopy shows numerous superficial, bleeding mucosal defects. Which of the following is the most likely diagnosis?
An X-ray shows a lytic lesion in the calcaneus in a young adult. Biopsy shows the following diagnosis:
Cytopathology Indian Medical PG Practice Questions and MCQs
Question 21: A 27-year-old man develops acute pain and swelling of the left knee 5 days after an episode of urethritis. On physical examination, the left knee is swollen, warm, and tender to the touch. No other joints are affected. Laboratory examination of fluid aspirated from the left knee joint shows numerous neutrophils. A Gram stain of the fluid shows gram-negative intracellular diplococci. No crystals are seen. Which of the following infectious agents is most likely responsible for his condition?
- A. Borrelia burgdorferi
- B. Haemophilus influenzae
- C. Neisseria gonorrhoeae (Correct Answer)
- D. Staphylococcus aureus
Explanation: ### Explanation **Correct Answer: C. Neisseria gonorrhoeae** **1. Why it is correct:** The clinical presentation describes **Acute Suppurative Arthritis** (Septic Arthritis). [1] The patient is a young, sexually active male with a history of recent **urethritis**, followed by acute monoarthritis of the knee. The definitive diagnostic clue is the Gram stain finding of **Gram-negative intracellular diplococci** within neutrophils. [3] *Neisseria gonorrhoeae* is the most common cause of septic arthritis in sexually active young adults. [1] It typically presents as either a localized monoarthritis (as seen here) or a disseminated triad of tenosynovitis, dermatitis, and polyarthralgia. **2. Why other options are incorrect:** * **A. Borrelia burgdorferi:** Causes Lyme disease. While it can cause late-stage chronic arthritis (usually the knee), it is associated with tick bites and would not show Gram-negative diplococci on Gram stain. * **B. Haemophilus influenzae:** Previously a common cause of septic arthritis in children under 2 years old, but its incidence has significantly decreased due to the Hib vaccine. It is a Gram-negative coccobacillus, not a diplococcus. * **D. Staphylococcus aureus:** The most common cause of non-gonococcal suppurative arthritis across all age groups. [1] However, it is a **Gram-positive coccus** in clusters, which contradicts the Gram stain findings in this case. **3. High-Yield Clinical Pearls for NEET-PG:** * **Most common cause of Septic Arthritis (Overall):** *Staphylococcus aureus*. * **Most common cause in sexually active young adults:** *Neisseria gonorrhoeae*. [1] * **Most common cause in Sickle Cell Anemia patients:** *Salmonella* (though *S. aureus* is still frequent). * **Synovial Fluid Analysis:** In septic arthritis, the WBC count is typically **>50,000 cells/mm³** with >75% neutrophils. * **Culture:** Gonococcal arthritis can be "culture-negative" on routine media; it requires **Thayer-Martin (Chocolate agar)** for growth. [2] **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Bones, Joints, and Soft Tissue Tumors, pp. 1215-1216. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Osteoarticular And Connective Tissue Disease, pp. 681-682. [3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Infectious Diseases, pp. 375-376.
Question 22: A 60-year-old woman with arthritis suffers a massive stroke and expires. At autopsy, the proximal phalangeal joint tissue shows pannus, synovial cell hyperplasia, and lymphoid follicles. Which of the following best describes the pathogenesis of pannus formation in this patient?
- A. Calcification of the synovium
- B. Chronic inflammation of synovium (Correct Answer)
- C. Degeneration of cartilage
- D. Dislocation of a portion of bone
Explanation: ### Explanation **Correct Answer: B. Chronic inflammation of synovium** The clinical presentation of a 60-year-old woman with arthritis and autopsy findings of **pannus**, **synovial cell hyperplasia**, and **lymphoid follicles** [1] is classic for **Rheumatoid Arthritis (RA)**. [2] **Pathogenesis:** Pannus is the hallmark of RA. It is an abnormal layer of fibrovascular tissue (granulation tissue) consisting of proliferating synovial cells, inflammatory cells (T-cells, B-cells, macrophages), and neovascularization [1], [2]. This formation is driven by **chronic inflammation of the synovium** (synovitis). Cytokines like TNF and IL-1 stimulate the synovial fibroblasts to proliferate and secrete proteases (collagenases), which eventually destroy the underlying articular cartilage and bone [1], [2]. **Analysis of Incorrect Options:** * **A. Calcification of the synovium:** While chronic inflammation can lead to dystrophic calcification in some tissues, it is not the mechanism behind pannus formation. * **C. Degeneration of cartilage:** This is the primary feature of **Osteoarthritis (OA)**. In RA, cartilage destruction is a *consequence* of the pannus, not the cause of its formation. * **D. Dislocation of a portion of bone:** This describes a mechanical injury or a late-stage complication of joint destruction (subluxation), but it does not describe the biological pathogenesis of pannus. **NEET-PG High-Yield Pearls:** * **Pannus Composition:** Proliferating synovial lining cells + Inflammatory cells + Granulation tissue + Fibroblasts [1], [2]. * **Rice Bodies:** Fibrinous aggregates shed into the joint space in RA. * **Rheumatoid Factor (RF):** An IgM antibody against the Fc portion of IgG. * **Anti-CCP:** Most specific marker for Rheumatoid Arthritis [2]. * **Morphology:** Look for "Palisading Granulomas" in Rheumatoid nodules. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Osteoarticular And Connective Tissue Disease, pp. 677-678. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Bones, Joints, and Soft Tissue Tumors, pp. 1212-1214.
Question 23: In which color cap vacutainer is NaF used?
- A. Grey (Correct Answer)
- B. Yellow
- C. Red
- D. Blue
Explanation: **Explanation:** The correct answer is **Grey**. **1. Why Grey is Correct:** The grey-top vacutainer contains **Sodium Fluoride (NaF)**, often combined with Potassium Oxalate. NaF acts as an **antiglycolytic agent**. It preserves glucose levels in the blood sample by inhibiting the enzyme **enolase** in the glycolytic pathway. This prevents RBCs and WBCs from metabolizing the glucose in the tube, ensuring an accurate measurement of blood sugar levels (Plasma Glucose) even if the sample processing is delayed. **2. Why Other Options are Incorrect:** * **Yellow (B):** Contains **SST (Serum Separating Tube)** with a clot activator and gel. It is used for biochemistry, immunology, and serology. * **Red (C):** Contains **no additive** or a clot activator. It is used for serum testing, chemistry, and cross-matching. * **Blue (D):** Contains **3.2% Sodium Citrate**. It is used for coagulation studies (PT, APTT) as it chelates calcium reversibly. **3. Clinical Pearls & High-Yield Facts for NEET-PG:** * **Order of Draw:** Remember the mnemonic **"B**e **C**areful **R**egarding **G**reen **L**ight **G**o" (Blue → Citrate, Red/Yellow → Serum, Green → Heparin, Lavender → EDTA, Grey → Fluoride). * **Lavender/Purple Top:** Contains **EDTA** (Ethylene Diamine Tetra-acetic Acid). It is the gold standard for CBC and HbA1c. * **Green Top:** Contains **Heparin** (Lithium or Sodium). It is used for arterial blood gases (ABG) and cytogenetics. * **NaF Ratio:** NaF preserves glucose for up to **48–72 hours** at room temperature. Without it, glucose levels drop by approximately 5–7% per hour due to glycolysis.
Question 24: A mother delivered an infant at 38 weeks gestation without complications. Soon after delivery, she experienced respiratory distress, uncontrolled vaginal bleeding, shock, and multiorgan failure, leading to death. Autopsy revealed masses of debris and epithelial squamous cells in the pulmonary microcirculation. What was the likely cause of death?
- A. Sheehan syndrome
- B. Chorioamnionitis
- C. Abruptio placentae
- D. Amniotic fluid embolism (Correct Answer)
Explanation: ### Explanation **Correct Answer: D. Amniotic fluid embolism (AFE)** The clinical presentation of sudden respiratory distress, cardiovascular collapse (shock), and disseminated intravascular coagulation (DIC) leading to uncontrolled bleeding immediately postpartum is classic for **Amniotic Fluid Embolism**. The definitive diagnosis is made histologically (often at autopsy) by identifying fetal elements in the maternal pulmonary microvasculature [1]. These include **squamous cells** (from fetal skin), **lanugo hair**, **fat** (from vernix caseosa), and **mucin** (from fetal gut) [1]. The pathophysiology involves a breach in the placental membrane, allowing amniotic fluid to enter maternal circulation, triggering a severe anaphylactoid reaction and activation of the coagulation cascade. **Incorrect Options:** * **A. Sheehan syndrome:** This is ischemic necrosis of the anterior pituitary due to severe postpartum hemorrhage. While it involves bleeding, it presents with failure of lactation and amenorrhea later, not acute respiratory failure or sudden death. * **B. Chorioamnionitis:** This is an infection of the fetal membranes. It typically presents with maternal fever, uterine tenderness, and foul-smelling discharge, rather than sudden cardiovascular collapse. * **C. Abruptio placentae:** This is the premature separation of the placenta. While it can cause DIC and shock, it occurs *before* delivery and would not show fetal squamous cells in the maternal lungs. **NEET-PG High-Yield Pearls:** * **Histological Stain:** **Attwood’s stain** (alcian blue-phloxine) is used to highlight fetal squames and mucin in maternal lung tissue. * **Triad of AFE:** Hypoxia (Respiratory distress), Hypotension (Shock), and Coagulopathy (DIC). * **Incidence:** Rare but has a very high mortality rate (>80%). * **Common Site of Emboli:** Small pulmonary arteries and arterioles [1]. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Respiratory Tract Disease, pp. 323-324.
Question 25: Cervical smear fixation is done by?
- A. Ethyl alcohol (Correct Answer)
- B. Acetone
- C. Xylene
- D. Formalin
Explanation: **Explanation:** **1. Why Ethyl Alcohol is Correct:** The standard staining technique for cervical smears (Pap smears) is the **Papanicolaou (Pap) stain**. For optimal results, cells must be fixed while still wet to preserve nuclear detail and prevent air-drying artifacts [1]. **95% Ethyl alcohol (Ethanol)** is the gold standard fixative for cytopathology. It acts as a dehydrating fixative that coagulates proteins, stabilizing the chromatin and allowing for the crisp nuclear visualization necessary to identify dysplastic or malignant changes. **2. Why Other Options are Incorrect:** * **Acetone:** While it is a fixative, it causes extreme shrinkage of cells and makes them brittle. It is rarely used in routine cytology, except occasionally for rapid fixation of smears for certain enzyme histochemistry. * **Xylene:** This is a **clearing agent**, not a fixative. It is used during the processing of tissue sections or after staining to make the specimen transparent before mounting. * **Formalin (10% Neutral Buffered Formalin):** This is the standard fixative for **histopathology** (tissue biopsies). In cytology, formalin causes significant cell shrinkage and alters the staining characteristics of the Pap stain, making it unsuitable for cervical smears. **3. High-Yield Clinical Pearls for NEET-PG:** * **Ideal Fixation Time:** Minimum 15–30 minutes. * **Alternative Fixatives:** If 95% Ethanol is unavailable, **100% Methanol**, **80% Propanol**, or **Ether-Alcohol mixture** (1:1 ratio) can be used. * **Spray Fixatives:** These often contain alcohols and polyethylene glycol (PEG). The PEG forms a protective thin film over the smear. * **The "Golden Rule":** To avoid "Air-drying artifact," the slide must be immersed in the fixative immediately (within seconds) after the smear is prepared [1]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Female Genital Tract, pp. 1010-1011.
Question 26: Which of the following conditions cannot be diagnosed using fine needle aspiration cytology?
- A. Plasmacytoma
- B. Aneurysmal bone cyst (Correct Answer)
- C. Tubercular lymphadenitis
- D. Papillary carcinoma thyroid
Explanation: **Explanation:** The correct answer is **Aneurysmal Bone Cyst (ABC)**. The fundamental principle of Fine Needle Aspiration Cytology (FNAC) is the evaluation of cellular morphology. However, ABC is a **cystic, blood-filled lesion** characterized by large, blood-containing spaces separated by thin fibrous septa [1]. An aspirate from an ABC typically yields only **frank blood** with very few cellular elements (hemosiderin-laden macrophages or occasional giant cells), which are non-specific. Because the diagnosis of ABC relies heavily on the **architectural arrangement** of the septa and the exclusion of solid components, it requires a histopathological examination (biopsy) rather than cytology [1]. **Analysis of Incorrect Options:** * **Plasmacytoma:** This is a plasma cell neoplasm. FNAC of the involved site shows a monotonous population of atypical plasma cells (eccentric nuclei, perinuclear hof, "clock-face" chromatin), making it easily diagnosable via cytology. * **Tubercular Lymphadenitis:** FNAC is the gold standard for initial diagnosis. It reveals characteristic epithelioid cell granulomas, Langhans giant cells, and necrotic (caseous) debris. * **Papillary Carcinoma Thyroid:** This is the most common thyroid malignancy diagnosed by FNAC. It features pathognomonic nuclear findings: Orphan Annie eye nuclei (clearing), nuclear grooves, and intranuclear cytoplasmic inclusions. **Clinical Pearls for NEET-PG:** * **FNAC Limitation:** FNAC cannot distinguish between **Follicular Adenoma** and **Follicular Carcinoma** of the thyroid because it cannot evaluate capsular or vascular invasion (architectural features). * **ABC Radiographic Sign:** Look for the "Fluid-fluid levels" on MRI/CT, which is highly suggestive of ABC [1]. * **High-Yield:** FNAC is generally avoided in suspected cases of **Hemangioma** (risk of bleeding) and **Hydatid cyst** (risk of anaphylaxis). **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.
Question 27: A 17-year-old female underwent a fine needle aspiration cytology (FNAC) for a lump in the breast which was well defined, non-tender and mobile. Which of the following pathological features suggests a diagnosis of a benign lesion?
- A. Dyscohesive ductal epithelial cells without cellular fragments
- B. Tightly arranged ductal epithelial cells with dyscohesive bare nuclei (Correct Answer)
- C. Stromal predominance with hyperplasia of spindle cells
- D. Polymorphism with single or arranged ductal epithelial cells
Explanation: ### Explanation The clinical presentation of a 17-year-old female with a well-defined, mobile, non-tender breast lump is classic for a **Fibroadenoma** (the most common benign breast tumor in young women) [1]. **1. Why Option B is Correct:** In FNAC of a benign lesion like Fibroadenoma, the hallmark features are **biphasic patterns**: * **Tightly arranged ductal epithelial cells:** These often appear as large, branching, "antler-like" or "staghorn" clusters. * **Dyscohesive bare nuclei:** Also known as **"Bipolar nuclei"** or "myoepithelial nuclei." These are found scattered in the background [2]. Their presence is the most reliable cytological indicator of a **benign** breast lesion, as they represent the preserved myoepithelial layer. **2. Analysis of Incorrect Options:** * **Option A:** Dyscohesion (loss of cell-to-cell adhesion) in ductal cells is a hallmark of **malignancy** (e.g., Ductal Carcinoma). Benign cells typically stick together in cohesive sheets. * **Option C:** While Fibroadenomas have a stromal component, "hyperplasia of spindle cells" with stromal predominance is more characteristic of a **Phyllodes tumor**, which can be borderline or malignant. * **Option D:** "Polymorphism" (pleomorphism) and single malignant cells are features of **Invasive Ductal Carcinoma**. Benign lesions show monomorphism (uniform nuclei). **3. High-Yield Clinical Pearls for NEET-PG:** * **Fibroadenoma:** Known as the "Breast Mouse" due to its high mobility [1]. * **Triple Test:** Clinical exam + Imaging (USG/Mammography) + Cytology (FNAC). * **Cytology Triad of Fibroadenoma:** 1. Staghorn epithelial clusters, 2. Bipolar bare nuclei, 3. Fragments of myxoid stroma. * **Key Differentiator:** The absence of myoepithelial cells/bare nuclei in a cellular smear should always raise suspicion of malignancy [2]. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Liver And Biliary System Disease, pp. 448-449. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Breast, pp. 1052-1054.
Question 28: A 20-year-old female patient presented with a thyroid swelling. Which of the following is least likely to be diagnosed by fine needle aspiration cytology?
- A. Non-Hodgkin's lymphoma of thyroid
- B. Medullary carcinoma of thyroid
- C. Papillary carcinoma of thyroid
- D. Follicular carcinoma of thyroid (Correct Answer)
Explanation: **Explanation:** The correct answer is **Follicular Carcinoma of Thyroid (Option D)**. The fundamental principle of Fine Needle Aspiration Cytology (FNAC) is the evaluation of **cytological (cellular) features** rather than **architectural features**. 1. **Why Follicular Carcinoma is the correct answer:** The diagnosis of Follicular Carcinoma requires the demonstration of **capsular invasion** or **vascular invasion** [2]. Since FNAC only aspirates individual cells or small clusters, it cannot assess the integrity of the tumor capsule or the presence of cells within blood vessels. On cytology, Follicular Carcinoma and Follicular Adenoma appear identical (both show follicular cells in microfollicular patterns); therefore, they are collectively reported as "Follicular Neoplasm." A definitive diagnosis of carcinoma can only be made via histopathology [4]. 2. **Why other options are incorrect:** * **Papillary Carcinoma (C):** Diagnosed by characteristic nuclear features (Orphan Annie eye nuclei, nuclear grooves, and intranuclear inclusions) which are easily visible on FNAC [1]. * **Medullary Carcinoma (B):** Identified by salt-and-pepper chromatin, spindle-shaped cells, and the presence of amyloid stroma (confirmed with Congo Red stain) [2]. * **Non-Hodgkin’s Lymphoma (A):** Diagnosed by a monomorphic population of atypical lymphoid cells, often distinguishable from thyroiditis on cytology [3]. **High-Yield Clinical Pearls for NEET-PG:** * **FNAC** is the investigation of choice (IOC) for the initial evaluation of a thyroid nodule. * **Hürthle cell neoplasms** also cannot be distinguished as benign or malignant by FNAC for the same reasons as follicular neoplasms. * **Bethesda System** is used for reporting thyroid cytopathology (Category IV corresponds to Follicular Neoplasm). * **Psammoma bodies** are a high-yield cytological finding in Papillary Thyroid Carcinoma. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Endocrine System, p. 1099. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Liver And Biliary System Disease, pp. 430-431. [3] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Liver And Biliary System Disease, pp. 428-429. [4] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Endocrine System, pp. 1100-1101.
Question 29: A 50-year-old woman with long-standing rheumatoid arthritis complains of weakness and fatigue. She states that her stools have recently become black after taking a new nonsteroidal anti-inflammatory drug (NSAID). Gastroscopy shows numerous superficial, bleeding mucosal defects. Which of the following is the most likely diagnosis?
- A. Acute erosive gastritis (Correct Answer)
- B. Early gastric cancer
- C. Helicobacter pylori gastritis
- D. Menetrier disease
Explanation: ### Explanation **Correct Answer: A. Acute erosive gastritis** **Mechanism:** The clinical presentation describes **Acute Erosive Gastritis**, a common cause of upper GI bleeding [1]. The underlying mechanism involves the inhibition of **Cyclooxygenase (COX-1 and COX-2)** enzymes by NSAIDs [2]. This leads to decreased synthesis of **Prostaglandins (PGE2 and PGI2)**, which are essential for gastric mucosal protection. Prostaglandins normally stimulate bicarbonate and mucus secretion, maintain mucosal blood flow, and promote epithelial regeneration [1]. Their absence results in superficial mucosal defects (erosions) that do not extend through the muscularis mucosae, leading to hematemesis or melena (black stools). **Analysis of Incorrect Options:** * **B. Early gastric cancer:** Typically presents as a malignant lesion confined to the mucosa or submucosa. While it can cause bleeding, the acute onset immediately following NSAID use and the presence of "numerous superficial defects" strongly favor a drug-induced etiology. * **C. Helicobacter pylori gastritis:** This is a chronic condition characterized by antral-predominant inflammation. While it increases the risk of peptic ulcers, it does not typically present as sudden, diffuse superficial erosions immediately after starting NSAIDs. * **D. Menetrier disease:** A rare hypertrophic gastropathy characterized by massive enlargement of gastric folds (rugae) due to excess TGF-α [1]. It presents with protein-losing enteropathy and achlorhydria, not acute erosive bleeding. **NEET-PG High-Yield Pearls:** * **Erosion vs. Ulcer:** An erosion is a superficial epithelial breach (above muscularis mucosae); an ulcer is a deeper lesion extending into the submucosa or deeper. * **Curling Ulcer:** Acute gastric stress ulcer associated with severe **burns** (hypovolemia → mucosal ischemia) [1]. * **Cushing Ulcer:** Acute gastric ulcer associated with **CNS injury/increased intracranial pressure** (vagal stimulation → hypersecretion of gastric acid). * **NSAIDs** are the most common cause of acute erosive gastritis in patients with chronic inflammatory conditions like Rheumatoid Arthritis [2]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Gastrointestinal Tract, pp. 767-769. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Infectious Diseases, pp. 430-431.
Question 30: An X-ray shows a lytic lesion in the calcaneus in a young adult. Biopsy shows the following diagnosis:
- A. Pigmented villonodular synovitis (Correct Answer)
- B. Ochronosis
- C. Osteomyelitis
- D. Eumycosis
Explanation: ***Pigmented villonodular synovitis*** - **PVNS** commonly affects young adults and can cause **lytic bone lesions** in locations like the calcaneus due to its aggressive synovial proliferation and bone erosion. - Biopsy shows characteristic **hemosiderin-laden macrophages**, **foam cells**, **multinucleated giant cells**, and **villous synovial proliferation** with brownish pigmentation. *Ochronosis* - Associated with **alkaptonuria** and deposition of **homogentisic acid**, causing dark cartilage and joint degeneration rather than lytic bone lesions. - Typically presents with **blue-black pigmentation** of cartilage and sclerae, not the cellular features seen in this biopsy. *Osteomyelitis* - Would show **inflammatory infiltrate** with neutrophils, bacteria, and necrotic tissue on biopsy, not the specialized cells described. - Usually presents with **systemic signs** like fever and elevated inflammatory markers, plus characteristic **sequestra** formation on imaging. *Eumycosis* - Refers to **fungal infections** that would demonstrate **fungal hyphae** and **spores** on biopsy with associated inflammatory response. - Typically shows **granulomatous inflammation** with epithelioid cells and Langhans giant cells, not the pigmented macrophages of PVNS.
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Basic Principles of Cytopathology
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Specimen Collection and Processing
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Gynecologic Cytology
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Respiratory Tract Cytology
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Urinary Tract Cytology
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Effusion Cytology
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Fine Needle Aspiration Cytology
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Gastrointestinal Tract Cytology
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Ancillary Studies in Cytopathology
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Quality Assurance in Cytopathology
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