1.What is dry syndrome?
Dry syndrome is a chronic inflammatory autoimmune disease that mainly involves exocrine glands. In addition to dry mouth and dry eyes due to decreased function of salivary glands and lacrimal glands, dry nasal cavity and dry itchy skin are also present. Due to elevated immunoglobulin in the blood, purpura-like rash may appear on the skin of the whole body, especially on the skin of the lower limbs. Dry syndrome is an autoimmune disease involving antibodies, which can cause damage to multiple organs such as lungs, blood, nerves and kidneys.
The former refers to the dry syndrome without another clearly diagnosed connective tissue disease; the latter refers to the dry syndrome occurring in another clearly diagnosed connective tissue disease such as systemic lupus erythematosus, rheumatoid arthritis and so on.
2.Which tissues and organs are mainly invaded by dry syndrome? What are the clinical manifestations?
Local manifestations.
(1) Dry mouth syndrome
Due to salivary gland lesion, the lack of salivary mucin causes the following symptoms.
(1) 70%-80% of the patients complain of dry mouth and need to drink water frequently, and solid food must be sent down with water or liquid food, and sometimes need to get up to drink water at night;
②Rampant dental caries is one of the characteristics of this disease, which shows that the teeth gradually become black and then fall off in small pieces, and finally only the residual roots remain;
③Adult mumps, 50% of patients show intermittent alternating parotid swelling and pain, involving unilateral or bilateral;
④The tongue shows painful tongue, dry and cracked tongue, and atrophied and smooth tongue papillae;
⑤ Oral mucosa with ulcers or secondary infection.
(2) Dry keratoconjunctivitis
Symptoms such as dry eyes, foreign body sensation and few tears due to the decrease of mucin secreted by lacrimal glands, and in severe cases, painful crying without tears.
(3) Other superficial areas
Such as the nose, hard palate, trachea and its branches, digestive tract mucosa, and exocrine glands of vaginal mucosa can be involved, resulting in less secretion and corresponding symptoms.
Systemic manifestations.
In addition to dry mouth and eyes manifestations patients may also develop systemic symptoms such as malaise and hypothermia. About 2/3 of patients have systemic damage.
(1) Skin
The pathological basis of skin lesions is localized vasculitis, with allergic purpura-like rash common, mostly in the lower extremities, as red papules with clear borders of the size of rice grains, which do not fade when pressed and appear in batches. The duration of each batch is about 10 days, and it may fade on its own and leave brown pigmentation.
(2) Skeletal muscle
Arthralgia is more common, and only a small percentage of the joints are swollen, but they are not severe and transient, and joint destruction does not usually occur. Myositis is seen in about 5% of patients.
(3) Kidney
Renal damage is seen in 30%-50% of patients, mainly involving the distal renal tubules, and manifests as hypokalemic muscle paralysis due to type I renal tubular acidosis, with renal calcification, renal stones and chondromalacia in severe cases.
(4) Lung
The main pathology of the lungs is interstitial lesions, some of them appear diffuse and interstitial fibrosis, and a few die due to respiratory failure. Another small percentage of patients develop pulmonary hypertension.
(5) Digestive system
The gastrointestinal tract may have non-specific symptoms such as atrophic gastritis, decreased gastric acid, and dyspepsia due to lesions of the exocrine glands in its mucosal layer. About 20% of patients have liver damage, often combined with primary biliary cirrhosis.
(6) Neurological system
The incidence of involvement of the nervous system is about 5%. Peripheral nerve damage is the most common, and is associated with vasculitis.
(7) Hematologic system
Leukopenia or/and thrombocytopenia may occur, and bleeding tendency may occur in severe cases of low platelets. The incidence of lymphoma in this disease is approximately four times higher than in the normal population. Patients may develop angioimmunoblastoma lymphadenopathy (with macroglobulinemia), non-Hodgkin’s lymphoma, and multiple myeloma.
3.What tests should be done for dry syndrome?
A variety of autoantibodies can be detected in the serum of patients with dry syndrome, such as anti-nuclear antibody, anti-SSA antibody, anti-SSB antibody, rheumatoid factor and hyperimmunoglobulinemia. At the same time, dry eye test, lower lip gland biopsy, salivary gland nuclear examination, lung CT examination, etc. should be done.
4.What is the relationship between autoimmune hepatitis and dry syndrome?
Patients with dry syndrome may have enlarged liver and abnormal liver function. Liver puncture may also show the pathological changes of chronic active hepatitis or prolonged hepatitis, and some of them may see the chronic inflammation of intrahepatic bile duct. The combination of primary dry incandescent syndrome with autoimmune liver diseases such as autoimmune hepatitis and primary biliary cirrhosis is common in clinical practice.