Overview
Dry syndrome is a chronic inflammatory autoimmune disease that primarily involves the exocrine glands. It is also known as autoimmune exocrine gland epithelial cell infection or autoimmune exocrinopathy because the immune inflammatory response is mainly expressed 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 the dry syndrome that occurs in another CTD with clear diagnosis such as systemic lupus erythematosus and rheumatoid arthritis. This guideline mainly describes primary dry syndrome.
Primary dry syndrome is a global disease, the prevalence of which is 0.3-0.7% in our population, and 3-4% in the elderly population. The disease is more common in women, and the ratio of men to women is 1:9-20. The age of onset is mostly 40-50 years old, but also seen in children.
Clinical manifestations
The onset of the disease is insidious, and most patients have difficulty in stating a definite time of onset. The clinical manifestations are diverse. The severity of the disease varies widely.
Local manifestations
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 become 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.
2.Rampant dental caries is one of the characteristics of this disease. About 50% of the patients have multiple caries which is difficult to control the development, showing that the teeth gradually become black and then fall off in small pieces, and finally only the residual roots remain.
3.Adult mumps, 50% of patients show intermittent alternating parotid swelling and pain, involving unilaterally or bilaterally. Most of them can subside on their own in about 10 days, but sometimes the enlargement persists. A few have enlargement of the submandibular gland and, less frequently, of the sublingual gland. Some of them are accompanied by fever. Some people with persistent enlargement of parotid gland should be alerted to the possibility of malignant lymphoma.
4. The tongue shows pain, dryness and cracking of the tongue, and atrophy and smoothness of the tongue papillae.
5. The oral mucosa appears to be ulcerated or secondary to infection.
Dry keratoconjunctivitis This presents with dry eyes, foreign body sensation, and few tears due to reduced mucin secretion from the lacrimal glands, and in severe cases, painful crying without tears. Some patients have recurrent purulent infections of the eyelid margin, conjunctivitis, and keratitis.
Other superficial sites such as the nose, hard palate, trachea and its branches, digestive tract mucosa, and exocrine glands of the vaginal mucosa can be involved, resulting in less secretion and corresponding symptoms.
Systemic manifestations
In addition to dryness of the mouth and eyes, patients may also develop systemic symptoms such as malaise and hypothermia. About 2/3 of patients have systemic damage.
Skin
The pathological basis of skin lesions is localized vasculitis. There are the following manifestations
1, allergic purpura-like rash: mostly seen in the lower extremities, is a rice-grain-sized red papule with clear borders, does not fade when pressed, and appears in batches. The duration of each batch is about 10 days, which can fade on its own and leave brown pigmentation.
2.Erythema nodosum is less common.
3.Reynolds phenomenon
Most of them are not serious and do not cause ulceration or atrophy of the corresponding tissues at the fingertips.
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 characteristic feature of the disease. Myositis is seen in about 5% of patients.
Kidney
Renal damage is reported in about 30-50% of patients, mainly involving the distal tubules, and manifests as hypokalemic muscle paralysis due to type I renal tubular acidosis. 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 percentage of patients present with more pronounced glomerular damage, with clinical manifestations of massive proteinuria, hypoalbuminemia, and even renal insufficiency.
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, which can lead to respiratory failure and death in a minority of cases. 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. The prognosis is poor in patients with pulmonary fibrosis and severe pulmonary hypertension.
Digestive system
The gastrointestinal tract can present with non-specific symptoms such as atrophic gastritis, decreased gastric acid, and dyspepsia due to lesions of the exocrine glands in its mucosal layer. Approximately 20% of patients have liver damage, with a clinical spectrum ranging from jaundice to no clinical symptoms but liver function impairment. The liver pathology is diverse, with small intrahepatic bile duct walls and
The incidence of involvement of the nervous system is about 5%. Peripheral nerve damage is the most common, and either central or peripheral nerve damage is associated with vasculitis.
Hematologic system
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 have been reports of angioimmunoblastoma lymphadenopathy (with macroglobulinemia), non-Hodgkin’s lymphoma and multiple myeloma in patients with primary dry syndrome.