Correct Answer: C. Lymphocytic infiltration and destruction of salivary and lacrimal glands
Sjögren's syndrome (SS) is a chronic autoimmune disorder characterized by lymphocytic infiltration and destruction of exocrine glands, particularly the salivary and lacrimal glands, leading to xerostomia (dry mouth) and xerophthalmia (dry eyes). The presence of anti-Ro (SSA) and anti-La (SSB) antibodies is pathognomonic for primary Sjögren's syndrome. These are autoantibodies directed against ribonucleoproteins in the nucleus and cytoplasm of epithelial cells. The fundamental pathological mechanism involves T-cell and B-cell mediated autoimmunity, where CD4+ and CD8+ T lymphocytes infiltrate the glandular tissue, leading to progressive destruction of acinar cells. This is a Type IV hypersensitivity reaction (cell-mediated immunity), not Type I. The lymphocytic infiltration is predominantly composed of activated B cells and T cells that produce autoantibodies and pro-inflammatory cytokines. In Indian clinical practice, Sjögren's syndrome is increasingly recognized, particularly in women of reproductive and middle age. The diagnosis is confirmed by positive anti-Ro/SSA and anti-La/SSB antibodies, along with clinical features and supportive investigations like Schirmer's test and salivary gland biopsy showing lymphocytic infiltration with acinar destruction.
Why the other options are wrong
A. IgE-mediated hypersensitivity reaction — This describes Type I hypersensitivity (immediate, IgE-mediated), which is allergic in nature and occurs within minutes to hours. Sjögren's syndrome is a Type IV hypersensitivity (delayed, cell-mediated) autoimmune disorder developing over months to years. IgE plays no role in the pathogenesis of Sjögren's syndrome. The presence of anti-Ro/SSA and anti-La/SSB antibodies indicates a T-cell and B-cell driven autoimmune process, not mast cell degranulation. B. Destruction of exocrine glands by neutrophils — While neutrophils may be present in inflammatory infiltrates, they are not the primary destructive cells in Sjögren's syndrome. The hallmark histopathology shows lymphocytic (T cell and B cell) infiltration, not neutrophilic infiltration. Neutrophil-mediated destruction is characteristic of conditions like vasculitis or acute bacterial infections, not autoimmune exocrinopathy. The anti-Ro/SSA and anti-La/SSB antibodies target intracellular antigens, triggering lymphocyte-mediated immunity rather than neutrophil activation. D. Deposition of amyloid in salivary glands — Amyloid deposition in salivary glands is seen in systemic amyloidosis (AL or AA type), not in Sjögren's syndrome. Amyloidosis presents with different clinical features and serological markers. Sjögren's syndrome is characterized by lymphocytic infiltration and glandular destruction, not amyloid deposition. The positive anti-Ro/SSA and anti-La/SSB antibodies are specific to Sjögren's syndrome and are not associated with amyloidosis. This option confuses two distinct pathological processes.
High-Yield Facts
- Anti-Ro/SSA and anti-La/SSB antibodies are pathognomonic for primary Sjögren's syndrome; anti-La/SSB is more specific (95%) but less sensitive (40-60%) than anti-Ro/SSA (40-60% sensitivity, 95% specificity).
- Type IV hypersensitivity (cell-mediated, T-lymphocyte driven) is the underlying mechanism in Sjögren's syndrome, not Type I, II, or III.
- Lymphocytic infiltration in Sjögren's syndrome is predominantly CD4+ T cells and B cells; histology shows focal lymphocytic sialadenitis with acinar destruction and replacement by lymphoid tissue.
- Xerostomia and xerophthalmia result from progressive destruction of salivary and lacrimal acinar cells, reducing saliva and tear production by >50%.
- Schirmer's test (≤5 mm in 5 minutes) and salivary gland biopsy showing lymphocytic infiltration are diagnostic confirmatory tests in Indian clinical practice.
Mnemonics
SJÖGREN'S = Autoimmune Exocrinopathy Salivary gland destruction | Joint involvement (arthralgia) | Öcular dryness (xerophthalmia) | Glandular infiltration (lymphocytes) | Ro/SSA & La/SSB antibodies | Exocrine dysfunction | Non-Hodgkin lymphoma risk (5-10%) | Systemic manifestations (fatigue, fever) Anti-Ro/SSA vs Anti-La/SSB: Sensitivity-Specificity Trade-off Ro/SSA: 40-60% sensitivity, 95% specificity (present in primary & secondary SS, lupus). La/SSB: 40-60% sensitivity, 95% specificity (ONLY in primary SS, never alone without Ro/SSA). Use: La/SSB is more specific for primary Sjögren's; Ro/SSA is more common but less specific.
NBE Trap
NBE may pair Sjögren's syndrome with neutrophilic infiltration (mimicking vasculitis) or amyloid deposition (mimicking systemic amyloidosis) to trap students who confuse autoimmune exocrinopathy with other inflammatory or infiltrative disorders. The key discriminator is the presence of anti-Ro/SSA and anti-La/SSB antibodies, which are pathognomonic for lymphocyte-mediated autoimmunity.
Clinical Pearl
In Indian clinical practice, Sjögren's syndrome is often underdiagnosed because patients present with isolated xerostomia or xerophthalmia, which may be attributed to age or medication side effects. Testing for anti-Ro/SSA and anti-La/SSB antibodies in any middle-aged woman with dry eyes and mouth should be routine, as early recognition allows immunosuppressive therapy to slow glandular destruction and reduce the 5-10% risk of non-Hodgkin lymphoma development.
_Reference: Robbins Ch. 6 (Diseases of Immunity); Harrison Ch. 330 (Sjögren's Syndrome); Park's Textbook of Preventive and Social Medicine (Autoimmune Disorders)_