Diseases of the Oral Cavity and Salivary Glands — MCQs

A 16-year-old female patient presents with a one-week history of small ulcers on her cheeks and tongue. On general examination, a mild rise in temperature is noted. Oral examination reveals multiple ulcers on the buccal and labial mucosa. She also reports that she has her board exams in one week. What is the likely diagnosis?

Q248Easy

Which stain is used to identify premalignant lesions of the oral cavity?

Q249Easy

Acinic cell carcinomas of the salivary gland arise most often in which location?

Q250Medium

Which odontogenic tumor, when treated with simple curettage, is most likely to recur?

Diseases of the Oral Cavity and Salivary Glands Indian Medical PG Practice Questions and MCQs

Question 241: What is the investigation of choice for parotid gland calculi?

A. X-ray
B. Ultrasound (USG)
C. Sialography (Correct Answer)
D. CT scan

Explanation: **Explanation:** The investigation of choice for parotid gland calculi (sialolithiasis) is **Sialography**. This involves the injection of a radio-opaque contrast medium into the salivary duct followed by radiographic imaging. **Why Sialography is the Correct Answer:** Unlike the submandibular gland, where 80% of stones are radio-opaque, approximately **60-80% of parotid stones are radiolucent** (composed mainly of organic matter). Sialography is the gold standard because it identifies these radiolucent stones as "filling defects" within the ductal system. It also provides superior detail regarding ductal anatomy, helping to identify strictures or diverticula associated with chronic sialadenitis. **Analysis of Incorrect Options:** * **A. X-ray:** Most parotid stones are radiolucent and will not be visible on a plain radiograph (e.g., AP view or intraoral films). * **B. Ultrasound (USG):** While often the first-line screening tool due to its non-invasive nature, it is operator-dependent and may miss small stones (<2mm) or those located deep in the parotid tail. * **D. CT Scan:** Highly sensitive for calcified stones, but less effective than sialography for visualizing the internal ductal architecture and radiolucent obstructions. **NEET-PG High-Yield Pearls:** * **Submandibular vs. Parotid:** Submandibular stones are more common (80%) and usually radio-opaque. Parotid stones are less common (20%) and usually radiolucent. * **Contraindication:** Sialography should **never** be performed during an acute infection (sialadenitis) as it can worsen the condition or spread the infection. * **Modern Gold Standard:** While Sialography is the traditional "investigation of choice" in exams, **MR Sialography** (non-invasive) and **Diagnostic Sialendoscopy** are increasingly preferred in modern clinical practice.

Question 242: Which of the following is NOT typically a white lesion found in the oral cavity?

A. Spongy nevus
B. Lichen planus
C. Candidiasis
D. Erythroplakia (Correct Answer)

Explanation: **Explanation:** The correct answer is **D. Erythroplakia**. **1. Why Erythroplakia is the correct answer:** As the name implies (*Erythro* = red, *plakia* = patch), Erythroplakia presents as a fiery red, velvety patch on the oral mucosa that cannot be characterized clinically or pathologically as any other condition. Unlike white lesions, which often involve hyperkeratosis (thickening of the keratin layer), Erythroplakia is characterized by epithelial atrophy and increased vascularity. It is clinically significant because it has a much higher transformation rate into **Squamous Cell Carcinoma (SCC)** compared to Leukoplakia (white patches). **2. Why the other options are incorrect:** * **Spongy Nevus (White Sponge Nevus):** A rare genetic condition (autosomal dominant) causing thick, bilateral, white, "spongy" plaques, usually on the buccal mucosa. * **Lichen Planus:** An inflammatory condition that typically presents as **Wickham’s striae** (white, lace-like patterns) on the buccal mucosa. * **Candidiasis (Oral Thrush):** A fungal infection caused by *Candida albicans* that presents as "curdy white" patches. A key diagnostic feature is that these patches **can be scraped off**, leaving an erythematous (red) base. **NEET-PG High-Yield Pearls:** * **Pre-malignant potential:** Erythroplakia > Speckled Leukoplakia > Proliferative Verrucous Leukoplakia > Homogenous Leukoplakia. * **Biopsy Rule:** Any red or white lesion persisting for more than 2 weeks after removing local irritants must be biopsied to rule out malignancy. * **Fordyce Spots:** These are ectopic sebaceous glands (yellowish-white spots) and are considered a normal anatomical variant, not a disease.

Question 243: Which of the following is NOT a precancerous lesion of the oral cavity?

A. Leukoplakia
B. Erythroplakia
C. Diffuse oral submucous fibrosis
D. Diffuse aphthous ulcers (Correct Answer)

Explanation: **Explanation:** The correct answer is **Diffuse aphthous ulcers**. **1. Why it is the correct answer:** Aphthous ulcers (canker sores) are common, painful, inflammatory lesions of the oral mucosa. They are **not** precancerous. Their etiology is typically related to immune dysregulation, stress, nutritional deficiencies (B12, Iron, Folate), or trauma. They heal without leaving a permanent change in the cellular architecture and do not carry a risk of malignant transformation into squamous cell carcinoma. **2. Analysis of incorrect options (Precancerous Lesions):** * **Leukoplakia:** Defined by the WHO as a "white patch or plaque that cannot be characterized clinically or pathologically as any other disease." It is the most common precancerous lesion, with a malignant transformation rate of approximately 3–5%. * **Erythroplakia:** This refers to a fiery red patch that cannot be attributed to any other cause. It is the **most dangerous** precancerous lesion, with a malignant transformation rate as high as 50–90%. * **Oral Submucous Fibrosis (OSMF):** A chronic, progressive condition characterized by juxta-epithelial fibrosis. It is strongly associated with **areca nut (betel nut)** chewing. It is considered a precancerous condition with a transformation rate of about 7–13%. **3. High-Yield Clinical Pearls for NEET-PG:** * **Precancerous Lesion:** A morphologically altered tissue in which cancer is more likely to occur than its normal counterpart (e.g., Leukoplakia, Erythroplakia). * **Precancerous Condition:** A generalized state associated with a significantly increased risk of cancer (e.g., OSMF, Lichen Planus, Xeroderma pigmentosum, Plummer-Vinson Syndrome). * **Speckled Leukoplakia:** Also known as Erythroleukoplakia; it carries a higher risk of malignancy than homogenous leukoplakia. * **Most common site for Oral Cancer:** Lateral border of the tongue.

Question 244: Tobacco usage has been associated with which of the following oral pathological changes?

A. Hyperkeratosis (Correct Answer)
B. Erythema
C. Ulceration
D. None of the above

Explanation: **Explanation:** The correct answer is **Hyperkeratosis**. **Why Hyperkeratosis is correct:** Tobacco contains various chemical irritants and carcinogens (such as polycyclic aromatic hydrocarbons and nitrosamines). Chronic exposure to these irritants triggers a protective physiological response in the oral mucosa. To shield the underlying delicate epithelium, the body increases the production of keratin, leading to thickening of the *stratum corneum*. This process is known as **hyperkeratosis**. Clinically, this often manifests as **Leukoplakia**—a white, non-scrapable patch that is considered a classic premalignant lesion associated with tobacco use. **Why other options are incorrect:** * **Erythema:** While tobacco can cause inflammation, erythema (redness) is more characteristic of *Erythroplakia*. While serious, the primary and most common structural change induced by the irritants in tobacco is the protective thickening (keratosis) rather than simple vascular congestion. * **Ulceration:** Ulceration is typically a sign of malignancy (Squamous Cell Carcinoma) or acute trauma. Tobacco itself causes chronic proliferative changes (hyperplasia/keratosis) rather than acute loss of epithelial continuity (ulceration). **High-Yield NEET-PG Pearls:** * **Leukoplakia:** The most common precancerous lesion of the oral cavity. The risk of malignant transformation is higher in the "non-homogeneous" (speckled) variety. * **Smoker’s Palate (Stomatitis Nicotina):** Characterized by a diffuse white palate with red dots, which represent the inflamed openings of minor salivary glands. * **Site Predilection:** Tobacco chewing is most strongly associated with carcinoma of the **buccal mucosa** (often called the "Indian Oral Cancer"). * **Histology:** Look for "epithelial dysplasia" in biopsy reports of tobacco-related lesions to assess the risk of malignancy.

Question 245: Masticator space infection usually results from:

A. Infections of the last two lower molars
B. Non-aseptic technique in local anesthesia
C. External or internal trauma to the mandibular angle region
D. All of the above (Correct Answer)

Explanation: **Explanation:** The **masticator space** is a deep neck space enclosed by the splitting of the superficial layer of the deep cervical fascia. It contains the muscles of mastication (masseter, pterygoids, and temporalis), the ramus of the mandible, and the mandibular nerve (V3). **Why "All of the Above" is correct:** 1. **Infections of the last two lower molars (Option A):** This is the **most common cause**. The roots of the 2nd and 3rd lower molars often lie below the attachment of the mylohyoid muscle. Odontogenic infections (pericoronitis or apical abscesses) from these teeth can easily penetrate the thin lingual or buccal cortex of the mandible to enter the submandibular or masticator spaces. 2. **Non-aseptic technique in local anesthesia (Option B):** An **inferior alveolar nerve block** involves injecting anesthetic into the pterygomandibular space (a compartment of the masticator space). If the needle is contaminated, it can directly seed bacteria into this deep space. 3. **Trauma (Option C):** Fractures of the mandibular ramus or angle, as well as penetrating injuries (internal or external), provide a direct pathway for pathogens to enter the fascial compartment. **Clinical Pearls for NEET-PG:** * **Trismus:** This is the hallmark clinical feature of masticator space infection due to irritation of the medial pterygoid and masseter muscles. * **Boundaries:** It is bounded laterally by the masseteric fascia and medially by the pterygoid fascia. * **Ludwig’s Angina vs. Masticator Space:** While Ludwig’s Angina involves the submandibular/sublingual spaces and presents with "woody" swelling of the floor of the mouth, masticator space infections present with severe trismus and swelling over the ramus of the mandible. * **Management:** High-dose antibiotics and surgical drainage (intraoral or extraoral) if an abscess forms.

Question 246: Which of the following develops from an unerupted tooth?

A. Dental cyst
B. Dentigerous cyst (Correct Answer)
C. Both of the above
D. None of the above

Explanation: ### Explanation **Correct Answer: B. Dentigerous cyst** #### Why Dentigerous Cyst is Correct: A **Dentigerous cyst** (also known as a follicular cyst) is an odontogenic cyst that originates from the **reduced enamel epithelium** surrounding the crown of an **un-erupted or impacted tooth**. It is the second most common odontogenic cyst after the radicular cyst. * **Pathophysiology:** Fluid accumulates between the reduced enamel epithelium and the tooth crown, causing the cyst to attach at the **cemento-enamel junction (CEJ)**. * **Common Site:** It most frequently involves the **mandibular third molar**, followed by the maxillary canine. #### Why Other Options are Incorrect: * **A. Dental Cyst (Radicular Cyst):** This is an inflammatory cyst that develops at the apex of a **non-vital, erupted tooth**. It arises from the epithelial rests of Malassez in the periodontal ligament due to pulp necrosis or dental caries. It does *not* involve an unerupted tooth. * **C & D:** Since the mechanisms of formation for dental and dentigerous cysts are distinct (inflammatory vs. developmental), only Option B is correct. #### High-Yield Clinical Pearls for NEET-PG: * **Radiological Appearance:** Dentigerous cysts appear as a well-defined, unilocular radiolucency surrounding the crown of an impacted tooth. * **Most Common Odontogenic Cyst:** Radicular (Dental) cyst. * **Most Common Developmental Odontogenic Cyst:** Dentigerous cyst. * **Potential Complications:** If left untreated, a dentigerous cyst can lead to pathological fractures or transform into an **Ameloblastoma** or Squamous Cell Carcinoma. * **Treatment:** Surgical enucleation and extraction of the associated impacted tooth.

Question 247: A 16-year-old female patient presents with a one-week history of small ulcers on her cheeks and tongue. On general examination, a mild rise in temperature is noted. Oral examination reveals multiple ulcers on the buccal and labial mucosa. She also reports that she has her board exams in one week. What is the likely diagnosis?

A. Bullous pemphigoid
B. Minor aphthous ulcers (Correct Answer)
C. Traumatic ulcer
D. Tuberculoid ulcer

Explanation: **Explanation:** The clinical presentation of multiple small, painful ulcers on the non-keratinized mucosa (buccal and labial) in a young patient, triggered by stress (upcoming exams), is classic for **Minor Aphthous Ulcers** (Canker sores). These are the most common type of recurrent aphthous stomatitis (RAS), typically measuring less than 1 cm and healing without scarring within 7–10 days. A mild prodromal fever is occasionally noted. **Analysis of Options:** * **Minor Aphthous Ulcers (Correct):** Characteristically occur on mobile, non-keratinized mucosa. Stress is a well-documented precipitating factor. * **Bullous Pemphigoid:** An autoimmune blistering disease primarily affecting the skin of the elderly. Oral involvement is rare (unlike Pemphigus Vulgaris) and would present as large, ruptured bullae rather than small, multiple ulcers in a teenager. * **Traumatic Ulcer:** Usually presents as a single, large, painful ulcer with an identifiable cause (e.g., a sharp tooth or dental appliance). It does not typically present with multiple lesions or systemic symptoms like fever. * **Tuberculoid Ulcer:** Typically presents as a chronic, painless, "undermined" ulcer, often on the dorsum of the tongue. It is usually secondary to pulmonary TB and lacks the acute, stress-related onset seen here. **High-Yield Clinical Pearls for NEET-PG:** * **Major Aphthous Ulcers (Sutton’s Disease):** >1 cm, deeper, very painful, and heal **with scarring**. * **Herpetiform Ulcers:** Multiple crops of tiny (1-2 mm) ulcers that may coalesce; not related to the Herpes virus despite the name. * **Treatment:** Primarily symptomatic (topical steroids like triamcinolone acetonide, topical anesthetics). * **Associations:** Rule out Behcet’s syndrome if oral ulcers are associated with genital ulcers and uveitis.

Question 248: Which stain is used to identify premalignant lesions of the oral cavity?

A. Toluidine blue (Correct Answer)
B. Malachite green
C. Potassium iodide
D. Iodine

Explanation: **Explanation:** **Toluidine Blue (Option A)** is a basic metachromatic thiazine dye that has a high affinity for acidic tissue components, specifically **nucleic acids**. Malignant and premalignant cells (dysplasia/carcinoma-in-situ) exhibit increased DNA synthesis, rapid cell division, and a higher nuclear-to-cytoplasmic ratio compared to normal cells. When applied topically to the oral mucosa, the dye is selectively retained in these areas of high DNA content, staining them deep blue. This is a vital staining technique used as a screening tool to demarcate biopsy sites and identify "occult" lesions not easily visible to the naked eye. **Analysis of Incorrect Options:** * **Malachite Green (Option B):** Primarily used as a biological stain for spores and in aquaculture as a fungicide; it has no clinical role in screening oral malignancy. * **Potassium Iodide (Option C):** Often used in the management of hyperthyroidism (Lugol’s iodine) or as an expectorant, but not as a diagnostic stain for oral lesions. * **Iodine (Option D):** While **Schiller’s test** (using Lugol’s iodine) is used in the cervix to identify dysplasia (where abnormal cells *fail* to take up the stain due to lack of glycogen), it is not the standard primary stain for oral premalignancy. **Clinical Pearls for NEET-PG:** * **False Positives:** Toluidine blue can stain inflammatory conditions (e.g., ulcers) because of the presence of inflammatory cells and debris. * **False Negatives:** Highly keratinized lesions (Leukoplakia) may not take up the stain well as the keratin acts as a barrier. * **Gold Standard:** Remember that vital staining is only a screening tool; **Incisional Biopsy** remains the definitive gold standard for diagnosing oral cancer.

Question 249: Acinic cell carcinomas of the salivary gland arise most often in which location?

A. Parotid gland (Correct Answer)
B. Minor salivary glands
C. Submandibular gland
D. Sublingual gland

Explanation: **Explanation:** **Acinic Cell Carcinoma (ACC)** is a low-grade malignant epithelial neoplasm of the salivary glands. The correct answer is the **Parotid gland**, as it is the site of origin for approximately **80% to 90%** of all cases. 1. **Why Parotid Gland is correct:** Acinic cell carcinoma is unique because it demonstrates serous acinar differentiation (cells containing zymogen-like granules). Since the parotid gland is the only major salivary gland composed almost entirely of **pure serous acini**, it is the most logical and frequent site for this tumor to arise. It represents about 10% of all parotid malignancies. 2. **Why other options are incorrect:** * **Minor Salivary Glands:** While ACC can occur here (most commonly in the buccal mucosa or palate), it is significantly less frequent than in the parotid. * **Submandibular/Sublingual Glands:** These glands are mixed (seromucous) or predominantly mucous. ACC is rare in these locations, accounting for less than 5% of cases. **High-Yield Clinical Pearls for NEET-PG:** * **Bilateralism:** Acinic cell carcinoma is the **second most common** salivary gland tumor to occur bilaterally (the most common being Warthin’s tumor). * **Demographics:** Unlike many other salivary malignancies, it shows a predilection for younger patients (often seen in the 2nd to 4th decades). * **Prognosis:** It is generally considered a "low-grade" malignancy with a favorable prognosis, though it can recur or metastasize years after initial treatment. * **Histology:** Look for "clear cells" or "blue dots" (zymogen granules) on PAS stain.

Question 250: Which odontogenic tumor, when treated with simple curettage, is most likely to recur?

A. Complex odontoma
B. Compound odontoma
C. Odontogenic myxoma (Correct Answer)
D. Ameloblastic fibroma

Explanation: **Explanation:** The correct answer is **Odontogenic Myxoma**. **1. Why Odontogenic Myxoma is correct:** Odontogenic myxoma is a benign but **locally aggressive** mesenchymal tumor. Its hallmark characteristic is its **gelatinous, non-encapsulated consistency** and a "loose" myxomatous stroma. Because it lacks a capsule, the tumor cells easily infiltrate the surrounding trabecular bone beyond the visible margins of the lesion. Simple curettage often leaves behind microscopic remnants, leading to a high recurrence rate (up to 25%). Therefore, the preferred treatment is wide local excision or resection with clear margins. **2. Why the other options are incorrect:** * **Complex and Compound Odontomas:** These are considered **hamartomas** rather than true neoplasms. They are well-circumscribed, encapsulated, and consist of mature dental tissues. Simple surgical enucleation or curettage is curative, and recurrence is extremely rare. * **Ameloblastic Fibroma:** This is a true mixed odontogenic tumor typically seen in younger patients. While it requires monitoring, it is generally well-demarcated and responds well to conservative surgical excision/enucleation compared to the infiltrative nature of a myxoma. **3. Clinical Pearls for NEET-PG:** * **Radiological Appearance:** Odontogenic myxoma typically presents as a multilocular radiolucency with a **"soap bubble," "honeycomb," or "tennis racket"** (straight septations) appearance. * **Histology:** Look for stellate and spindle-shaped cells in an abundant mucoid/myxomatous extracellular matrix (resembling the dental papilla). * **Age/Site:** Most common in the 2nd–3rd decades; the mandible is affected more frequently than the maxilla.

Practice by Chapter

Stomatitis

Practice Questions

Oral Ulcers

Practice Questions

Oral Leukoplakia

Practice Questions

Oral Cancers

Practice Questions

Sialadenitis

Practice Questions

Sialolithiasis

Practice Questions

Salivary Gland Tumors

Practice Questions

Ranula

Practice Questions

Xerostomia

Practice Questions

Sjögren's Syndrome

Practice Questions

Oral Manifestations of Systemic Diseases

Practice Questions

Temporomandibular Joint Disorders

Practice Questions

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