Introduction to Psoriatic Arthritis (PsA)

Introduction: Psoriatic arthritis (PsA) is seen in 3% to 5% of patients with psoriasis. Although most occur in patients with confirmed active skin diseases, some patients (especially children) develop joint disease before psoriasis. The degree of skin damage in psoriasis, although not related to the occurrence of arthritis, but the risk of psoriatic arthritis in people with a family history of spondyloodesis and generalized point-like concave changes in the nails. increase. The genetic relevance of psoriatic arthritis is heterogeneous. Causes: (1) Causes of the disease The causes of this disease vary from place to place, among which there are mainly genetic, infection, metabolic disorders, endocrine effects, neuropsychiatric factors and immune disorders. 1. Genetic factors This disease often has a tendency to family aggregation. The prevalence of first-degree family members is as high as 30%, and the risk of single-oval twins is 72%. The domestic report has a family history of 10% to 23.8%, and foreign reports are 10% to 80%, which is generally considered to be around 30%. The disease is autosomal dominant, with incomplete penetrance, but some are considered autosomal recessive or sexually inherited. 2. Infection factors (1) Viral infection: Some patients have been treated with antiviral therapy for patients with psoriasis and viral infection, and the condition of psoriatic arthritis is also relieved. (2) Streptococcal infection: It is reported that about 6% of patients have a history of pharyngeal infection and upper respiratory tract, and their anti-"O" titer is also increased. (3) Metabolic disorders: Some people believe that the three major metabolic disorders of fat, protein and sugar have pathogenic effects on this disease. Others believe that these three major metabolic abnormalities are following the discovery of the disease. Others believe that this disease and the three major substances It has nothing to do with metabolic disorders. (4) Endocrine dysfunction The related role of psoriasis and endocrine gland function has long been paid attention to. (5) Neuropsychiatric disorders: In the past, the literature often reported that mental factors are related to the disease. For example, trauma can sometimes cause the onset of the disease or aggravate the condition, and it is believed that this is due to the increase of vascular motor nerve tension after mental stimulation. However, during the Great Patriotic War of the former Soviet Union, there were many people with severe mental trauma, but the incidence of this disease was not seen. (B) the pathogenesis 1. Henseler et al. proposed to divide psoriasis into type 2 type I is hereditary (60% autosomal dominant), the onset age is light, males are 22 years old, females are 16 years old. The course of the disease is irregular and can be generalized. The positive rate of HLA-CW6 is as high as 85% (relative risk 4.5). 50% of patients with this type have psoriasis. Type II is sporadic, with a peak age of 60 years, and 15% of patients are associated with HLA-CW6 (relative risk is 7.3). This type of patient has no parental disease. Recent studies suggest that HLA is closely related to the clinical type of psoriatic arthritis. For example, asymmetric peripheral arthritis is associated with HLA-B38, B17, B13, CW6, and spondylitis is associated with B27 or B39. It was also found that early onset of arthritis was associated with HLA-DR4 and DRW53, disease severity was associated with DQW3, joint space narrowing and erosion were associated with HLA-A9 and B5. 2. It has been confirmed that there are eosinophilic inclusion bodies in the nucleus of the spine, but some people also deny the existence of such inclusion bodies. Although there seems to be some basis for the pathogenic effect of viral infection, the specific virus causing the disease has not yet been isolated. Young children often have a history of acute tonsillitis or upper respiratory tract infection, and the symptoms are relieved after penicillin treatment and removal of the tonsils. These all indicate that the infectious factor has a pathogenic effect on the disease. 3. It has been reported that there are two types of lesions in patients with this disease, oxaloacetate dehydrogenase combined with coenzyme II, which are involved in skin maturation and keratinization. It has also been found that the activity of lactate dehydrogenase and cytochrome oxidase in the blood of patients increases, and succinate dehydrogenase decreases. The changes in these enzymes are not necessarily primary or secondary, but they are sure to have an effect on the metabolism of sugar. Studies have found that the patient's skin lesions lack acyclic adenosine monophosphate. Proliferation and division of the epidermis is caused by the lack of cyclic adenosine monophosphate. Cyclic adenosine also activates phosphorylase, which can affect the metabolism of sugar. If the content of cyclic adenosine monophosphate in the epidermis is decreased, the glycogen content is increased, the mitosis of epidermal cells is enhanced, and the conversion rate is accelerated. The normal epidermal cell transformation time is 4 weeks, and the psoriasis conversion time can be reduced to 3 to 4 days, which indicates that the reduction of cyclic adenosine monophosphate content in the skin lesion has a certain pathogenic effect. 4. Farber pointed out that about one-third of patients with psoriasis during pregnancy can be relieved, and the condition deteriorates after delivery. It has also been reported in the country that the treatment of this disease with pregnancy urinary tract has achieved good results. Some patients may also have pituitary-adrenal dysfunction. Urine 17-ketosteroids are reduced. Clinically, treatment with glucocorticoids can achieve better results. 5. Pathology (1) Skin pathology: According to the characteristics of skin lesions, it is generally divided into vulgaris, pustular and erythrodermic types. 1 vulgaris type: the epidermis changes earlier, there is horny hyperplasia in the epidermis, mainly keratinization. The keratinized cells can be combined into a sheet, which is filled with air and refraction, so it is observed by the naked eye as silvery white scales. In the quiescent period, hyperkeratosis may be more pronounced than parakeratosis. Under the keratinized layer or keratinized layer, small abscesses composed of neutrophils are sometimes seen. This neutrophil is caused by the upper capillaries of the dermal papilla to swim to the surface, which is more common in early damage. Seen in old damage. The granular layer becomes thin or disappears, the spinous layer is thickened, accompanied by epidermal protrusion, and the ends are often thickened, sometimes connected to adjacent epidermal processes. There may be significant interstitial edema in the spinous cell layer at the top of the nipple. In early lesions, neutrophils and lymphocytes are scattered in the layer of spine cells. The dermal capillaries of the dermis are distorted and the wall is slightly thickened with mild to moderate inflammatory cell infiltration. In old damage, its infiltration is composed of lymphocytes and plasma cells. The infiltration of plasma cells is most prominent in the nipple. The nipple can be elongated upwards and edema, often extending to the surface keratinized layer. The spinous cell layer at the top is thinned, leaving only 2 to 3 layers of cells. There are often no granulosa cells, so it is easier to scratch the small blood vessels at the top of the nipple and cause clinical punctiform bleeding. Due to the extension and widening of the epidermal process, the dermal papilla grows and narrows accordingly, and is in the shape of a rod or a finger. 2 pustular type: its pathological changes are basically the same as the vulgaris, but there are large pustules in the keratinized layer, mainly neutrophils in the blister. The thickness of the spinous cell layer and the change of the rod-shaped nipple were not obvious. The inflammatory infiltration of the dermis is more serious, mainly lymphocytes, tissue cells and a small number of neutrophils. 3 erythrodermic type: except for the pathological features of psoriasis, other changes are similar to dermatitis, showing significant parakeratosis, thinning and disappearing of the granular layer, hypertrophy of the spinous cell layer, prolongation of the epidermal process, and obvious intracellular and extracellular Edema, but does not form blisters. Upper dermis of the dermis, vasodilatation and hyperemia, lymphocytes and neutrophils infiltrated around the blood vessels, sometimes eosinophils. Late infiltration is mostly lymphocytes, tissue cells and plasma cells. (2) Arthritis pathology: Basically similar to rheumatoid arthritis, but lacks typical rheumatoid arteritis. In the early stage, there may be synovial edema and hyperemia. Later, the synovial cells are slightly hyperplasia and villi are formed. Lymphocytes and plasma cells infiltrate around the synovial blood vessels. In the elderly, fibroblasts proliferate and synovial fibrosis occurs. A typical change is to cause osteolysis of the toe, which is caused by non-inflammatory hyperplasia of the periosteum and intermittent loss of cortical bone. At the same time, it may be accompanied by mild new bone formation caused by enhanced osteoblast activity, but the whole process is mainly related to osteolytic bone, and the change of the metatarsophalangeal joint is obvious. Symptoms: The ratio of male to female incidence is 1:1.04, the age of onset is 20 to 50 years old, and the peak is 40 years old. About 5% of patients with psoriasis develop psoriatic arthritis, most of whom have psoriasis, psoriatic arthritis occurs 5 to 10 years later, and about 1 in 5 patients have arthritis before Psoriasis, about 1 in 10 patients appear at the same time. One third of patients may have acute onset, with low or moderate fever or high fever, fatigue, poor appetite. 1. Arthritis is divided into peripheral arthritis and ankylosing spondylitis. (1) Peripheral arthritis: manifested as acute gout-like episodes, large toe involvement and elevated uric acid, and good response to colchicine treatment. The distinguishing point between this disease and gout is the absence of birefringent urate crystals in the joint effusion. In addition, the distal and proximal interphalangeal joints are the most common sites of early involvement, except for the first toe of the big toe. Its performance ranges from mild single joint involvement to extensive disabling polyarthritis. Clinically, peripheral arthritis is classified into 5 types: 1 typical psoriatic arthritis type: mainly involving the distal interphalangeal joint. This type is rare, and once it appears, it can prompt the diagnosis of the disease (Figures 3, 4, 5). 2 disabling arthritis type: due to severe phalanges, metacarpal or humeral bones, the bones become sharp, and form a pencil-like shape with a pen-like pen, or a mushroom-like shape, often accompanied by ankle arthritis. . Joint stiffness and osteolysis can occur in severe cases. 3 symmetrical arthritis type: all aspects are similar to rheumatoid arthritis, most patients with negative serum rheumatoid factor, a few rheumatoid factors can be positive. Some people think that the latter belongs to both psoriasis and rheumatoid arthritis. 4 less arthritis type: is the most common type of psoriatic arthritis, accounting for more than 70%. For asymmetry, individual proximal and distal interphalangeal joints and metacarpophalangeal joints are usually involved. This type of "sausage finger" caused by arthritis between the fingers and the acral follicle of individual fingers or toe flexors, it is considered that the asymmetry is less (single) joint involvement, which is the most common psoriatic arthritis. Characteristic performance. 5 peripheral arthritis combined with ankylosing spondylitis. In addition to the typical changes in the hand and foot joints, it is not uncommon for large joints such as the wrist, knee, ankle, elbow and shoulder joints to be affected. These large joints can be affected alone without acromegaly. Major joint involvement often occurs in the joint cavity, pain, tenderness or dysfunction. (2) Ankylosing spondylitis: about 40% of psoriatic arthritis, mainly involving the spine, more common in men, the ratio of male to female is about 6:1. Most patients with HLA-B27 genotype psoriasis can develop ankylosing spondylitis or ankle arthritis during the course of the disease. Also known as psoriatic spondylitis, but not necessarily clinical symptoms. Ankylosing spondylitis can involve any part of the spine, and cervical involvement is most common. It is also possible to directly involve a part of the spine without sputum arthritis (Fig. 6). Some patients may also have iritis. 2. Skin damage is also clinically divided into vulgaris, pustular and erythrodermic types. (1) Vulgaris: Most of the vulgaris are acute onset, the most common skin lesion in the clinic. It is usually an inflammatory red papule from the beginning to the mung bean. It gradually enlarges or merges into a sheet. The boundary is clear, there is an inflammatory redness around it, the base is infiltrated, and the surface is covered with multiple layers of silver-white dry scales. In addition to the surface scales, a layer of light red shiny translucent film is exposed, which is the epidermal layer of the epidermis, called the film phenomenon. The film is scraped off, that is, the top of the dermal papilla layer is reached. Here, if the capillaries are scraped, a small bleeding point may occur, which is called a point bleeding phenomenon (Auspitz phenomenon). White scales, shiny film and spotted bleeding are the characteristics of this type. In the process of disease development, skin lesions can be expressed in a variety of forms, such as skin lesions ranging from miliary to mung bean-sized papules, which are dotted in the whole body, called psoriasis; lesions continue to expand and the center fades to form a ring It is a map-shaped person, called map-like psoriasis; the distribution of lesions is banded or like a snake, called banded psoriasis; the number of lesions is large, the distribution is wide, and even spread to the whole body, said Generalized psoriasis; lesions occur in the scalp, eyebrows and ears, and have characteristics of seborrheic dermatitis, called seborrheic dermatitis-like psoriasis; lesions with erosion and exudation, moisturizing eczema After drying, it forms dark brown scales and crusted, and overlaps and accumulates such as clam shells, which is called crustaceous psoriasis; the lesions develop and are lichen-like changes, similar to lichen planus, called lichen planus-like psoriasis; Repeated episodes of skin lesions, after multiple treatments, the lesions showed hypertrophic dark red scales, small and thin, and merged into each other, like chronic eczema, called chronic hypertrophic psoriasis; the surface of the lesions formed flat warts , called sputum psoriasis. Skin lesions can occur anywhere in the body, but are most common in the scalp and extremities. A small number of patients can also be found in the axillary and inguinal folds, but rarely occur in the palmar and mucosa. Skin lesions are symmetrically distributed. In some cases, the patient's skin lesions are limited to a certain location, and thus their clinical characteristics may also be different. About half of the patients may have a change in the nail, and the common deck is somewhat concave, uneven, and tarnished. Sometimes there are lateral grooves, mediastinum, turbidity, hypertrophy, rough surface white nails. The nail bed changed to rupture and bleeding, with erythema plaques and horns. Under the nail, the keratinization, yellow-green debris and nail peeling were changed. The course of the disease is long and can last for decades. During this period, the patient's skin sensitivity is enhanced, such as trauma, friction, injection and acupuncture of normal skin, where lesions can often occur, a phenomenon known as "homotype reaction" (Kohner phenomenon). 2 quiescent period: the condition is stable in the stationary phase, basically no new skin lesions appear, but the old skin lesions do not fade. 3 regression period: inflammatory infiltration gradually subsided, scales decreased, rash shrink and flatten, there is a light red blush around, and finally the residual pigment can reduce white spots, and achieve clinical recovery. However, pigmentation can also occur. The extinction site usually begins with the trunk and upper limbs. The head and lower limbs tend to be more stubborn and often do not retreat. (2) pustular type, this type is rare in clinical, and can be divided into two subtypes of generalized and palmar pustule. 1 generalized pustular onset is urgent, can be spread throughout the body within a few weeks, accompanied by high fever, joint and muscle pain, general malaise and other symptoms, leukocytosis. On the basis of psoriasis, dense, miliary superficial aseptic abscesses can be seen with atypical scales on the surface. The rash is more common in the flexion and wrinkles of the extremities, and often causes erosion, exudation, scarring and purulent sputum due to friction. Small patches of pustules can also form in the buccal mucosa of the mouth. The nails can be shrunk, shattered or loosened. Some decks are thick and turbid. There are layers of scales under the deck, and small pustules can also appear on the nail bed. Vulvar skin lesions can occur after the condition is relieved. The disease can last for several months or longer and is prone to recurrence. 2 palmoplantar pustular lesions are limited to the hands and feet, mostly in the palm of the hand, the damage is symmetric erythema. There are many miliary-sized pustules on the erythema. The blister wall is not easy to rupture. After one or two weeks, it can dry itself and brown. Small pieces of scales may appear after the cockroaches fall off, and small bleeding spots may occur when the scales are removed. Later, clusters of new pustules can appear under the scales, resulting in pustules and scars on the same erythema. Skin pain and itching. This type may also be accompanied by symptoms such as low fever, headache, loss of appetite and general malaise, deformation of the nail, turbidity, hypertrophy and irregular ridges. In severe cases, there may be pus accumulation under the armor. Psoriasis lesions can be seen in other parts of the body at the same time. 3 erythrodermic type: It is a serious skin lesion that is rare in this disease. It is more common in adults and rarely affects children. This type can be caused by the use of irritating drugs or the long-term use of glucocorticoids for sudden withdrawal. It can also be derived from vulgaris or pustular lesions. The clinical manifestation is exfoliative dermatitis. At the beginning, the original skin lesions were flushed and rapidly expanded. Later, the skin of the whole body was diffuse red or dark red, and the inflammatory infiltration was obvious. The surface had a lot of bran-like scales and continued to fall off. Occurred in the hands and feet, often have a whole piece of horny exfoliation. A turbid, hypertrophic, deformed, or exfoliated nail. The oral and pharyngeal mucosa are both congested and red, accompanied by systemic symptoms such as chills, fever, and headache. The lymph nodes of the whole body can be swollen. The condition is more stubborn, the constant month or years of unhealed, even if cured, often relapse. 3. Other manifestations of psoriatic arthritis include different degrees of fever, occasionally superficial lymphadenopathy, sometimes muscle loss and idiopathic consumption, extensor tendon effusion, gastrointestinal Amyloidosis, aortic regurgitation, myopathy, Sjogren's syndrome and ocular inflammatory changes. The disease can also overlap with other seronegative polyarthritis. According to reports, this disease can be combined with other seropositive polyarthritis diseases to constitute the following overlapping syndrome: 1 psoriatic arthritis - Behcet's disease; 2 psoriatic arthritis - Reiter syndrome; 3 silver shavings Sick arthritis - Crohn's disease; 4 psoriatic arthritis - ulcerative colitis. Diagnosis is not difficult based on typical psoriatic lesions and clinical symptoms, particularly arthritis symptoms and typical X-ray findings. It must be determined that the patient has psoriasis or psoriasis nail disease, and then has joint damage and serum rheumatoid factor is negative, so that a diagnosis can be made. However, it is necessary to pay attention to the medical history and physical examination, especially the skin damage in the hidden parts, such as the scalp hair, navel, perineum and groin and other skin lesions are easily overlooked. Pay attention to distinguishing from other skin diseases. Read more...