Dry syndrome is a chronic inflammatory autoimmune disease that mainly involves the exocrine glands. It is also known as autoimmune exocrine gland epithelial cell inflammation or autoimmune exocrinopathy because the immune inflammatory response is mainly manifested in the epithelial cells of the exocrine glands. In addition to dry mouth and eyes due to decreased function of salivary glands and lacrimal glands, other exocrine glands and other organs outside the glands are also involved, resulting in multisystem damage. The disease is characterized by a variety of autoantibodies and hyperimmunoglobulinemia in the serum.
The disease is divided into two categories: primary and secondary, the former refers to dry syndrome without another clearly diagnosed connective tissue disease (CTD). The latter refers to dry syndrome that occurs in another clearly diagnosed connective tissue disease (CTD), such as systemic lupus erythematosus (SLE) and rheumatoid arthritis.
Primary dry syndrome is a global disease, and the prevalence rate in our population is 0.3%-0.7%, and the prevalence rate in the elderly population is 3%-4%. The disease is more common in women, and the ratio of men to women is 1:9-20. The onset of the disease is mostly in 40-50 years old, and also seen in children.
I. Clinical manifestations
The onset of the disease is insidious, and it is difficult for most patients to say when the disease started. The clinical manifestations are diverse. The severity of the disease varies greatly.
1.Local manifestations.
(1) Dry mouth syndrome: due to salivary gland lesions, the lack of salivary mucin causes the following common symptoms.
(1) 70%-80% of patients complain of dry mouth, but it is not always the first symptom or the main complaint. In serious cases, the oral mucosa, teeth and tongue are sticky, so that it is necessary to drink water frequently when speaking, and it is necessary to send down with water or liquid food when eating solid food, and sometimes it is necessary to get up and drink water at night.
②Rampant caries, about 50% of the patients have multiple caries which is difficult to control the development, and it shows that the teeth gradually become black and then fall off in small pieces, and finally only the residual root remains. It is one of the characteristics of this disease.
(iii) In adult mumps, 50% of patients present with intermittent alternating parotid swelling and pain, involving unilateral or bilateral. Most of them resolve on their own in about 10 days, but sometimes the enlargement persists. A few have submandibular gland enlargement and less frequently sublingual gland enlargement. Some of them are accompanied by fever. Some of them have persistent enlargement of the parotid gland and should be alerted to the possibility of malignant lymphoma.
④The tongue shows painful tongue, dry and cracked tongue, and atrophied and smooth tongue papillae.
(5) The oral mucosa appears to be ulcerated or secondary to infection.
(2) Dry keratoconjunctivitis: This is due to the decrease of mucin secreted by the lacrimal gland and presents with symptoms such as dry eyes, foreign body sensation, few tears, and in severe cases, painful crying without tears. Some patients have recurrent purulent infection of the eyelid margin, conjunctivitis, keratitis, etc.
(3) Other: superficial areas such as nose, hard palate, trachea and its branches, digestive tract mucosa, and exocrine glands of vaginal mucosa can be involved, causing less secretion and corresponding symptoms.
2. Systemic manifestations: In addition to dryness of the mouth and eyes, patients may also have systemic symptoms such as weakness and low fever. About 2/3 of patients have systemic damage.
(1) Skin: The pathological basis of skin lesions is local vasculitis. The following manifestations are present.
(1) Allergic purpura-like rash, mostly seen in the lower extremities, is a rice-grain-sized well-bounded red papule that does not fade when pressed and appears in batches. Each batch lasts for about 10 days and can fade on its own with brown pigmentation.
②Erythema nodosum is less common.
(3) Raynaud’s phenomenon is not serious and does not cause ulceration of the finger end or atrophy of the corresponding tissue.
(2) Skeletal muscle: arthralgia is more common. Only a small percentage of joints are swollen, but they are not severe and transient. Destruction of joint structures is not a feature of the disease. Myositis is seen in about 5% of patients.
(3) Kidney: Domestic reports show that about 30% to 50% of patients have kidney damage, mainly involving the distal tubules, manifested as hypokalemic muscle paralysis due to type I renal tubular acidosis, and in severe cases, renal calcification, kidney stones and chondromalacia. Nephrogenic dysuria, which manifests as polyhydramnios and polyuria, is also frequently seen in patients with tubular acidosis. A subclinical form of renal tubular acidosis can be seen in about 50% of patients by ammonium chloride loading test. Proximal renal tubular damage is less common. A small proportion of patients present with more pronounced glomerular damage, with clinical manifestations of massive proteinuria, hypoalbuminemia and even renal insufficiency.
(4) Lung: Most patients have no respiratory symptoms. Those with mild involvement present with a dry cough and those with severe involvement present with shortness of breath. The main pathology of the lungs is interstitial lesions, with some developing diffuse interstitial lung fibrosis, and a few may die of respiratory failure as a result. Early interstitial lung lesions are not apparent on lung X-rays and can only be detected by high-resolution lung CT. A small percentage of patients develop pulmonary hypertension. Those with pulmonary fibrosis and severe pulmonary hypertension have a poor prognosis.
(5) Digestive system: The gastrointestinal tract can show non-specific symptoms such as atrophic gastritis, decreased gastric acid, and dyspepsia due to lesions of the exocrine glands in its mucosal layer. Liver damage is seen in about 20% of patients, with a clinical spectrum ranging from jaundice to no clinical symptoms with liver function impairment. Liver pathology is diverse, with changes such as infiltration of the small intrahepatic bile duct wall and its surrounding lymphocytes and destruction of the border plate being prominent. Chronic pancreatitis is also not uncommon.
(6) Nerve: The incidence of involvement of the nervous system is about 5%. Peripheral nerve damage is the most common, whether central or peripheral nerve damage is associated with vasculitis.
(7) Hematologic: The disease may present with leukopenia or/and thrombocytopenia, and bleeding may occur in severe cases of low platelets. The incidence of lymphoma in this disease is about 44 times that of normal population. In China, there are reports of angioimmunoblastoma lymphadenopathy (with macroglobulinemia), non-Hodgkin’s lymphoma, multiple myeloma, etc. in patients with primary dry syndrome.
Diagnostic points
1.Symptoms and signs.
(1) Oral symptoms.
(1) Dry mouth for more than 3 months, need to drink frequently, get up in the middle of the night to drink water, etc.
(2) Recurrent or persistent enlargement of the parotid gland after adulthood.
(③) There is difficulty in swallowing dry food and must be assisted by water.
④There is rampant dental caries, dry and cracked tongue, and oral cavity is often secondary to mycobacterial infection.
(2) Ocular symptoms.
(1) Daily unbearable dry eyes that last for more than 3 months.
(2) Repeated sensation of “sand” blowing into the eye or frosting sensation.
(3) Artificial tears 3 or more times a day.
(3) Other: vaginal dryness, dry itchy skin, clinical or subclinical renal tubular acidosis or other systemic symptoms mentioned above.
2.Auxiliary examination.
(1) Eye.
①Schirmer (filter paper) test, i.e. ≤5mm/5 points (>5mm/5 points for normal people).
② Corneal staining, >10 staining points in each eye.
(③ tear film fragmentation time, i.e. ≤10 seconds (>10 seconds for normal people).
(2) Oral cavity.
(① Salivary flow rate, i.e. only natural outflow of saliva ≤ 1.5 ml was collected in 15 minutes (normal people > 1.5 ml).
(2) Parotid gland imaging, i.e., spillage of the terminal gland contrast is seen as a dotted or globular shadow.
④ salivary gland nuclear examination, i.e. poor salivary gland uptake, concentration, and excretion of nuclein.
(5) Histological examination of the lacrimal gland biopsy, i.e. 50 lymphocytes aggregated in 4 mm2 tissue is called a foci, and any foci showing lymphocytes ≥1 is (+).
(3) Urine: PH many times >6, it is necessary to further check the indicators related to renal tubular acidosis.
(4) Peripheral blood tests: low platelets or occasionally hemolytic anemia can be detected.
(5) Serum immunological tests.
(①Anti-SSA antibody, the most common autoantibody in this disease, is seen in 70% of patients.
(2) Anti-SSB antibodies, which are said to be the marker antibodies of the disease, are seen in 45% of patients.
(3) Hyperimmunoglobulinemia, both polyclonal, seen in 90% of patients.
(6) Other: such as pulmonary imaging, liver and kidney function measurement can be found in patients with corresponding systemic damage.
3.Diagnostic criteria
The international classification (diagnosis) criteria of dry syndrome in 2002 are as follows
I. Oral symptoms: 1 or more of the 3 items
1.Sensation of dry mouth daily for more than 3 months.
2.Recurrent or persistent enlargement of the parotid gland in adulthood.
3.Swallowing dry food with the help of water.
II. Eye symptoms: 1 or more of the 3 items
1.Feeling unbearable dry eyes daily for more than 3 months.
2.Have repeated sand-in-the-eye or gritty sensations.
3.Need to use artificial tears 3 times or more daily.
III. Ocular signs: Positive for any 1 or more of the following tests
1, Schirmer I test (+) (£5 mm/5 points).
2, Corneal staining (+) (³4 van Bijsterveld scoring method).
IV. Histological examination: pathology of the lower lacrimal gland showed foci of lymphocytes ³1 (referring to a foci of at least 50 lymphocytes aggregated in the interstitium of the lacrimal gland in 4mm2 tissue).
V. Salivary gland damage: positive for any 1 or more of the following tests
1, salivary flow rate (+) (£1.5 ml/15 min).
2, parotid gland angiography (+).
3, salivary gland isotope examination (+)
VI, autoantibodies: anti-SSA or anti-SSB (+) (double diffusion method)
1.Primary dry syndrome: Without any underlying disease, the diagnosis is made if 2 of the following are present
a., 4 or more entries in Table 1 are met, but must contain entry IV (histological examination) and/or entry VI (autoantibodies).
b., Positive for any 3 of the 4 entries of entry III, IV, V, VI.
2. Secondary dry syndrome: the patient has an underlying disease (e.g., any connective tissue disease) while meeting any 1 of entries I and II of Table 1 and any 2 of entries III, IV, and V.
3. Must exclude: history of cervicofacial radiation therapy, hepatitis C virus infection, AIDS, lymphoma, nodal disease, GVH disease, and application of anti-acetylcholine drugs (e.g., atropine, scopolamine, bromopamine tylenol, belladonna, etc.).
4. This disease should be differentiated from the following diseases
(1) Systemic lupus erythematosus Dry syndrome mostly appears in middle-aged and elderly women, fever, especially high fever is uncommon, no butterfly cheek rash, dry mouth and eyes are obvious, renal tubular acidosis is its common and main renal loss, hyperglobulinemia is obvious, hypocomplementemia is rare, good prognosis.
(2) Rheumatoid arthritis The symptoms of joint inflammation in dry syndrome are much less obvious and serious than those of rheumatoid arthritis, and there is rarely joint bone destruction, deformity and functional limitation. Anti-SSA and anti-SSB antibodies rarely appear in rheumatoid arthritis.
(3) Dry mouth in non-autoimmune diseases, such as senile glandular function, diabetic or pharmacological, depends on the medical history and the individual characteristics of each disease to differentiate.
Treatment options and principles]
There is no cure for this disease. The main measures are to improve the symptoms, control and delay the progression of tissue and organ damage caused by the immune response and secondary infection.
1.Improve the symptoms
(1) It is difficult to reduce dry mouth, so stop smoking, drinking alcohol and avoid taking drugs that cause dry mouth, such as atropine. Keep the mouth clean, rinse the mouth regularly, reduce the possibility of dental caries and oral secondary infection. Overseas, parasympathetic acetylcholine stimulants such as pilocarpine tablets and similar products can be taken to stimulate the secretion of the salivary glands that have not been destroyed to improve the symptoms of dry mouth. They have certain efficacy but also more adverse effects such as sweating and frequent urination.
(2) Dry keratoconjunctivitis can be given artificial tear drops to reduce dry eye symptoms and prevent corneal damage. Some eye creams can also be used to protect the cornea. Some people abroad use self-serum to treat the eye drops.
(3) Muscle and joint pains can be treated with non-steroidal anti-inflammatory drugs.
(4) Hypokalemia: correction of hypokalemic paralytic episodes can be done by intravenous potassium supplementation (potassium chloride), and after the condition stabilizes, it is changed to oral potassium salt solution or tablets, which some patients need to take for life to prevent the reoccurrence of hypokalemia. Most patients can still live and work normally after the correction of hypokalemia.
(5) Systemic damage should be treated according to the severity of the damaged organ. Adrenocorticotropic hormone should be given in the same dose as in other connective tissue diseases in combination with neurological, glomerulonephritis, interstitial lung lesions, liver damage, low blood cells, especially low platelets, and myositis. Immunosuppressive agents such as cyclophosphamide and azathioprine may be used in combination with other drugs for rapidly progressing disease. Combination chemotherapy is recommended for those with malignant lymphoma in an aggressive and timely manner.
Prognosis
The prognosis of this disease is good. Most of the patients with visceral damage can be controlled to achieve remission after appropriate treatment, but the disease can recur after stopping treatment. Among the visceral damage, those with progressive pulmonary fibrosis, central neuropathy, glomerular damage with renal insufficiency, and malignant lymphoma have a poor prognosis, while the rest of the systemic damage are mostly in remission and even resume daily life and work after appropriate treatment.