The mouth that will not stay wet

Correct answer: D. Sjogren syndrome

• A. Systemic sclerosis is associated with anti-Scl-70 (topoisomerase I) in diffuse disease and anticentromere antibodies in limited disease.
• B. Rheumatoid arthritis is characterised serologically by rheumatoid factor and anti-CCP antibodies. Anti-SSA may appear in RA patients with secondary Sjogren, but it is not the marker of RA itself.
• C. Anti-SSA can appear in lupus, particularly in subacute cutaneous and neonatal lupus, but the dry eyes and dry mouth in a patient with another autoimmune endocrine disease make Sjogren the far better fit.
• D. Correct. Anti-SSA (Ro) and anti-SSB (La) are the hallmark serologies of Sjogren syndrome, an autoimmune exocrinopathy that destroys salivary and lacrimal tissue. The combination with an existing autoimmune thyroid disease is a very typical clustering.

Correct answer: D. Focal aggregates of lymphocytes around ducts and acini

• A. Fatty replacement of acini is a feature of ageing and chronic sialadenitis. It may be present incidentally but it is not diagnostic and its presence alone does not support Sjogren.
• B. A dense plasma cell infiltrate with Russell bodies suggests a plasma cell disorder or chronic sclerosing sialadenitis, not the T-cell driven focal lesion of Sjogren.
• C. Non-caseating granulomas point to sarcoidosis, which is an important mimic of Sjogren because it also causes salivary swelling and dry mouth. The histology separates them cleanly.
• D. Correct. The diagnostic finding is focal lymphocytic sialadenitis: periductal collections of at least 50 lymphocytes, mostly CD4-positive T cells. A focus score of 1 or more per 4 square millimetres of glandular tissue supports the diagnosis.

Note: The recall option was written loosely as 'immunity cells' against a distractor of 'fat cells.' The examinable point is that the infiltrate is lymphocytic and focal, and that a focus score of 1 or more is the threshold.

Correct answer: B. Pilocarpine

• A. IS a cause. Diphenhydramine is a first-generation antihistamine with substantial anticholinergic action, producing dry mouth and sedation.
• B. CORRECT — this is the EXCEPTION. PILOCARPINE is a muscarinic AGONIST (a cholinergic drug) that INCREASES salivary secretion. It is prescribed precisely TO TREAT xerostomia, particularly in Sjögren syndrome and after head and neck radiotherapy. Cevimeline works the same way with somewhat greater M3 selectivity.
• C. IS a cause. Amitriptyline is a tricyclic antidepressant with powerful anticholinergic activity, and dry mouth is among its most common adverse effects.
• D. IS a cause. Scopolamine is a classic ANTImuscarinic agent, used for motion sickness and to reduce secretions — xerostomia is its expected effect.

Note: Pattern to hold onto: ANTI-cholinergic (antimuscarinic) drugs dry the mouth; CHOLINERGIC agonists such as pilocarpine and cevimeline wet it. Side effects of pilocarpine include sweating, flushing and GI upset; it is contraindicated in uncontrolled asthma and narrow-angle glaucoma.

Correct answer: B. Amitriptyline

• A. There is no history of head and neck radiation, so this can be excluded from the differential.
• B. Correct. Amitriptyline blocks muscarinic receptors on salivary acinar cells and is a classic pharmacological cause of dry mouth. In a patient with an autoimmune exocrinopathy the drug effect stacks on top of the disease and is the modifiable part.
• C. Levothyroxine replaces thyroid hormone and does not have anticholinergic activity. Xerostomia is not one of its recognised effects.
• D. A salivary stone would give episodic, meal-related swelling and pain in one gland. Nothing in the history describes that, and stones do not cause generalised dryness.

Correct answer: A. It supplies calcium and phosphate ions that redeposit into the enamel lattice

• A. Correct. Saliva is supersaturated with calcium and phosphate. When pH recovers above the critical value of about 5.5, these ions, assisted by statherin and proline-rich proteins that keep them in solution, redeposit into partially demineralised enamel.
• B. This reverses the chemistry. Lowering pH drives demineralisation. Saliva raises pH through its bicarbonate, phosphate and protein buffers, which is what permits remineralisation.
• C. Salivary glands do not synthesise fluoride. Salivary fluoride comes from systemic and topical exposure, and while it catalyses remineralisation it is not the source of the mineral.
• D. Salivary flow does clear debris, but mechanical washing is a clearance function. Remineralisation itself is a chemical process driven by ionic content.

Correct answer: D. Secretory IgA

• A. IgG is the dominant immunoglobulin of serum and reaches the mouth mainly through gingival crevicular fluid rather than through saliva itself.
• B. IgM is the first antibody produced in a primary response and is largely intravascular because of its size.
• C. IgE mediates type I hypersensitivity and is present in only trace quantities.
• D. Correct. Secretory IgA is the dominant immunoglobulin of all mucosal secretions including saliva. It is a dimer joined by a J chain and wrapped in a secretory component that protects it from proteolysis in the oral environment.

Correct answer: C. It blocks bacterial adherence to oral surfaces by immune exclusion

• A. Direct bacterial lysis is the job of lysozyme, which hydrolyses peptidoglycan, and of the complement membrane attack complex. IgA does not lyse organisms.
• B. Secretory IgA is a poor complement activator and does not use the classical pathway; this restraint is deliberate, since it avoids inflammation at a surface constantly exposed to commensals.
• C. Correct. Secretory IgA works by immune exclusion: it agglutinates organisms and coats their adhesins so they cannot attach to mucosa or tooth surfaces, and are cleared by swallowing. Preventing adherence is the key step it interrupts.
• D. Opsonisation for phagocytosis is chiefly an IgG function through Fc gamma receptors on neutrophils and macrophages.

Note: The recall recorded the option pair as antibacterial versus antiviral. Secretory IgA is in fact both, neutralising viruses as well as blocking bacterial adherence, so the discriminating idea is the mechanism of immune exclusion rather than the target organism.

Correct answer: C. Angular cheilitis secondary to xerostomia and Candida overgrowth

• A. Squamous cell carcinoma of the commissure would be an indurated ulcer or exophytic mass, not symmetrical bilateral fissuring, and it would not be the first consideration in this setting.
• B. Herpes labialis produces a vesicular then crusted lesion on the vermilion border, is usually unilateral, recurs at the same site and is preceded by prodromal tingling.
• C. Correct. Reduced salivary flow removes antimicrobial proteins and permits Candida overgrowth; saliva pooling in the commissural folds keeps the tissue macerated. Candida albicans, often with Staphylococcus aureus, produces the fissuring and erythema. Treat the dryness and the candidal component together.
• D. An allergic contact reaction is typically more diffuse across the lips and perioral skin with itching, and would not localise so precisely to both commissures.